* [syzbot] WARNING in wireless_send_event
@ 2022-09-23 16:05 syzbot
2022-09-24 7:10 ` [PATCH] Add linux-next specific files for 20220923 Hawkins Jiawei
` (3 more replies)
0 siblings, 4 replies; 18+ messages in thread
From: syzbot @ 2022-09-23 16:05 UTC (permalink / raw)
To: davem, edumazet, johannes, kuba, linux-kernel, linux-wireless,
netdev, pabeni, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: 483fed3b5dc8 Add linux-next specific files for 20220921
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1154ddd5080000
kernel config: https://syzkaller.appspot.com/x/.config?x=849cb9f70f15b1ba
dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c196f080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f12618880000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1cb3f4618323/disk-483fed3b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cc02cb30b495/vmlinux-483fed3b.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com
------------[ cut here ]------------
memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4)
WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623
Modules linked in:
CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022
RIP: 0010:wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623
Code: fa ff ff e8 cd b9 db f8 b9 04 00 00 00 4c 89 e6 48 c7 c2 e0 56 11 8b 48 c7 c7 20 56 11 8b c6 05 94 8e 2a 05 01 e8 b8 b0 a6 00 <0f> 0b e9 9b fa ff ff e8 6f ef 27 f9 e9 a6 fd ff ff e8 c5 ef 27 f9
RSP: 0018:ffffc90003b2fbc0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888021d157c0 RSI: ffffffff81620348 RDI: fffff52000765f6a
RBP: ffff88801e15c780 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 20676e696e6e6170 R12: 0000000000000008
R13: ffff888025a72640 R14: ffff8880225d402c R15: ffff8880225d4034
FS: 0000555556bd9300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbda677dfb8 CR3: 000000007b976000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022
wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955
wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline]
wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline]
wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049
sock_ioctl+0x285/0x640 net/socket.c:1220
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fbda6736af9
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd45e80138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbda6736af9
RDX: 0000000020000000 RSI: 0000000000008b04 RDI: 0000000000000003
RBP: 00007fbda66faca0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbda66fad30
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
---
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syzbot will keep track of this issue. See:
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syzbot can test patches for this issue, for details see:
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^ permalink raw reply [flat|nested] 18+ messages in thread* [PATCH] Add linux-next specific files for 20220923 2022-09-23 16:05 [syzbot] WARNING in wireless_send_event syzbot @ 2022-09-24 7:10 ` Hawkins Jiawei 2022-09-24 7:26 ` Kees Cook 2022-09-24 7:32 ` [syzbot] WARNING in wireless_send_event syzbot 2022-09-26 11:59 ` Hawkins Jiawei ` (2 subsequent siblings) 3 siblings, 2 replies; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-24 7:10 UTC (permalink / raw) To: syzbot+473754e5af963cf014cf, Johannes Berg, David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni Cc: linux-kernel, linux-wireless, netdev, syzkaller-bugs, 18801353760, yin31149, keescook, Stephen Rothwell From: Stephen Rothwell <sfr@canb.auug.org.au> > Hello, > > syzbot found the following issue on: > > HEAD commit: 483fed3b5dc8 Add linux-next specific files for 20220921 > git tree: linux-next > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1154ddd5080000 > kernel config: https://syzkaller.appspot.com/x/.config?x=849cb9f70f15b1ba > dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c196f080000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f12618880000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/1cb3f4618323/disk-483fed3b.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/cc02cb30b495/vmlinux-483fed3b.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > Modules linked in: > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022 > RIP: 0010:wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > Code: fa ff ff e8 cd b9 db f8 b9 04 00 00 00 4c 89 e6 48 c7 c2 e0 56 11 8b 48 c7 c7 20 56 11 8b c6 05 94 8e 2a 05 01 e8 b8 b0 a6 00 <0f> 0b e9 9b fa ff ff e8 6f ef 27 f9 e9 a6 fd ff ff e8 c5 ef 27 f9 > RSP: 0018:ffffc90003b2fbc0 EFLAGS: 00010286 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: ffff888021d157c0 RSI: ffffffff81620348 RDI: fffff52000765f6a > RBP: ffff88801e15c780 R08: 0000000000000005 R09: 0000000000000000 > R10: 0000000080000000 R11: 20676e696e6e6170 R12: 0000000000000008 > R13: ffff888025a72640 R14: ffff8880225d402c R15: ffff8880225d4034 > FS: 0000555556bd9300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fbda677dfb8 CR3: 000000007b976000 CR4: 00000000003506e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 > sock_ioctl+0x285/0x640 net/socket.c:1220 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:870 [inline] > __se_sys_ioctl fs/ioctl.c:856 [inline] > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > RIP: 0033:0x7fbda6736af9 > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ffd45e80138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbda6736af9 > RDX: 0000000020000000 RSI: 0000000000008b04 RDI: 0000000000000003 > RBP: 00007fbda66faca0 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbda66fad30 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > </TASK> I think this is the samiliar problem as what Kees Cook pointed out in https://lore.kernel.org/linux-next/202209211250.3049C29@keescook/ It seems that memcpy() will performs run-time buffer bounds checking, which triggers this warning. #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master diff --git a/include/linux/wireless.h b/include/linux/wireless.h index 2d1b54556eff..81603848b0aa 100644 --- a/include/linux/wireless.h +++ b/include/linux/wireless.h @@ -26,7 +26,10 @@ struct compat_iw_point { struct __compat_iw_event { __u16 len; /* Real length of this stuff */ __u16 cmd; /* Wireless IOCTL */ - compat_caddr_t pointer; + union { + compat_caddr_t pointer; + __DECLARE_FLEX_ARRAY(__u8, pointer_flex); + }; }; #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 76a80a41615b..9d0b50abbe09 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -620,7 +620,7 @@ void wireless_send_event(struct net_device * dev, extra, extra_len); } else { /* extra_len must be zero, so no if (extra) needed */ - memcpy(&compat_event->pointer, wrqu, + memcpy(&compat_event->pointer_flex, wrqu, hdr_len - IW_EV_COMPAT_LCP_LEN); } ^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [PATCH] Add linux-next specific files for 20220923 2022-09-24 7:10 ` [PATCH] Add linux-next specific files for 20220923 Hawkins Jiawei @ 2022-09-24 7:26 ` Kees Cook 2022-09-24 11:44 ` Hawkins Jiawei 2022-09-24 7:32 ` [syzbot] WARNING in wireless_send_event syzbot 1 sibling, 1 reply; 18+ messages in thread From: Kees Cook @ 2022-09-24 7:26 UTC (permalink / raw) To: Hawkins Jiawei Cc: syzbot+473754e5af963cf014cf, Johannes Berg, David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, linux-kernel, linux-wireless, netdev, syzkaller-bugs, 18801353760, Stephen Rothwell On Sat, Sep 24, 2022 at 03:10:34PM +0800, Hawkins Jiawei wrote: > From: Stephen Rothwell <sfr@canb.auug.org.au> > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 483fed3b5dc8 Add linux-next specific files for 20220921 > > git tree: linux-next > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1154ddd5080000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=849cb9f70f15b1ba > > dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c196f080000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f12618880000 > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/1cb3f4618323/disk-483fed3b.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/cc02cb30b495/vmlinux-483fed3b.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com > > > > ------------[ cut here ]------------ > > memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) > > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > > Modules linked in: > > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022 > > RIP: 0010:wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > > Code: fa ff ff e8 cd b9 db f8 b9 04 00 00 00 4c 89 e6 48 c7 c2 e0 56 11 8b 48 c7 c7 20 56 11 8b c6 05 94 8e 2a 05 01 e8 b8 b0 a6 00 <0f> 0b e9 9b fa ff ff e8 6f ef 27 f9 e9 a6 fd ff ff e8 c5 ef 27 f9 > > RSP: 0018:ffffc90003b2fbc0 EFLAGS: 00010286 > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > > RDX: ffff888021d157c0 RSI: ffffffff81620348 RDI: fffff52000765f6a > > RBP: ffff88801e15c780 R08: 0000000000000005 R09: 0000000000000000 > > R10: 0000000080000000 R11: 20676e696e6e6170 R12: 0000000000000008 > > R13: ffff888025a72640 R14: ffff8880225d402c R15: ffff8880225d4034 > > FS: 0000555556bd9300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007fbda677dfb8 CR3: 000000007b976000 CR4: 00000000003506e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > <TASK> > > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 > > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 > > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] > > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] > > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 > > sock_ioctl+0x285/0x640 net/socket.c:1220 > > vfs_ioctl fs/ioctl.c:51 [inline] > > __do_sys_ioctl fs/ioctl.c:870 [inline] > > __se_sys_ioctl fs/ioctl.c:856 [inline] > > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > RIP: 0033:0x7fbda6736af9 > > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > > RSP: 002b:00007ffd45e80138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbda6736af9 > > RDX: 0000000020000000 RSI: 0000000000008b04 RDI: 0000000000000003 > > RBP: 00007fbda66faca0 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbda66fad30 > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > </TASK> > > I think this is the samiliar problem as what Kees Cook pointed out in > https://lore.kernel.org/linux-next/202209211250.3049C29@keescook/ > > It seems that memcpy() will performs run-time buffer bounds > checking, which triggers this warning. > > #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git > master > > > diff --git a/include/linux/wireless.h b/include/linux/wireless.h > index 2d1b54556eff..81603848b0aa 100644 > --- a/include/linux/wireless.h > +++ b/include/linux/wireless.h > @@ -26,7 +26,10 @@ struct compat_iw_point { > struct __compat_iw_event { > __u16 len; /* Real length of this stuff */ > __u16 cmd; /* Wireless IOCTL */ > - compat_caddr_t pointer; > + union { > + compat_caddr_t pointer; > + __DECLARE_FLEX_ARRAY(__u8, pointer_flex); > + }; Is this expected to be dynamically sized? I assume so, given the "Real length" comment. :) > }; > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > index 76a80a41615b..9d0b50abbe09 100644 > --- a/net/wireless/wext-core.c > +++ b/net/wireless/wext-core.c > @@ -620,7 +620,7 @@ void wireless_send_event(struct net_device * dev, adding in more context code: memcpy(&compat_event->pointer, ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, hdr_len - IW_EV_COMPAT_LCP_LEN); if (extra_len) memcpy(((char *) compat_event) + hdr_len, extra, extra_len); The code above has "pointer" as a memcpy destination as well. I think that should be changed to pointer_flex as well, as the length calculation is the same. I wonder what FORTIFY will think about the second memcpy above. If I'm reading the math correctly, it might need to be: if (extra_len) { size_t offset = hdr_len - offsetof(typeof(*compat_event), pointer_flex); memcpy(&compat_event->pointer_flex[offset], extra, extra_len); } > } else { > /* extra_len must be zero, so no if (extra) needed */ > - memcpy(&compat_event->pointer, wrqu, > + memcpy(&compat_event->pointer_flex, wrqu, > hdr_len - IW_EV_COMPAT_LCP_LEN); > } > But otherwise, yes, looks like the right modification. Thanks for tackling this! It is quite a weird structure! :) -Kees -- Kees Cook ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] Add linux-next specific files for 20220923 2022-09-24 7:26 ` Kees Cook @ 2022-09-24 11:44 ` Hawkins Jiawei 2022-09-24 15:55 ` Hawkins Jiawei 0 siblings, 1 reply; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-24 11:44 UTC (permalink / raw) To: keescook Cc: 18801353760, davem, edumazet, johannes, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzbot+473754e5af963cf014cf, syzkaller-bugs, yin31149 Hi Kees, On Sat, 24 Sept 2022 at 15:26, Kees Cook <keescook@chromium.org> wrote: > > On Sat, Sep 24, 2022 at 03:10:34PM +0800, Hawkins Jiawei wrote: > > From: Stephen Rothwell <sfr@canb.auug.org.au> > > > > > Hello, > > > > > > syzbot found the following issue on: > > > > > > HEAD commit: 483fed3b5dc8 Add linux-next specific files for 20220921 > > > git tree: linux-next > > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1154ddd5080000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=849cb9f70f15b1ba > > > dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c196f080000 > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f12618880000 > > > > > > Downloadable assets: > > > disk image: https://storage.googleapis.com/syzbot-assets/1cb3f4618323/disk-483fed3b.raw.xz > > > vmlinux: https://storage.googleapis.com/syzbot-assets/cc02cb30b495/vmlinux-483fed3b.xz > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > Reported-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com > > > > > > ------------[ cut here ]------------ > > > memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) > > > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > > > Modules linked in: > > > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022 > > > RIP: 0010:wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > > > Code: fa ff ff e8 cd b9 db f8 b9 04 00 00 00 4c 89 e6 48 c7 c2 e0 56 11 8b 48 c7 c7 20 56 11 8b c6 05 94 8e 2a 05 01 e8 b8 b0 a6 00 <0f> 0b e9 9b fa ff ff e8 6f ef 27 f9 e9 a6 fd ff ff e8 c5 ef 27 f9 > > > RSP: 0018:ffffc90003b2fbc0 EFLAGS: 00010286 > > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > > > RDX: ffff888021d157c0 RSI: ffffffff81620348 RDI: fffff52000765f6a > > > RBP: ffff88801e15c780 R08: 0000000000000005 R09: 0000000000000000 > > > R10: 0000000080000000 R11: 20676e696e6e6170 R12: 0000000000000008 > > > R13: ffff888025a72640 R14: ffff8880225d402c R15: ffff8880225d4034 > > > FS: 0000555556bd9300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > CR2: 00007fbda677dfb8 CR3: 000000007b976000 CR4: 00000000003506e0 > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > Call Trace: > > > <TASK> > > > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 > > > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 > > > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] > > > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] > > > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 > > > sock_ioctl+0x285/0x640 net/socket.c:1220 > > > vfs_ioctl fs/ioctl.c:51 [inline] > > > __do_sys_ioctl fs/ioctl.c:870 [inline] > > > __se_sys_ioctl fs/ioctl.c:856 [inline] > > > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > RIP: 0033:0x7fbda6736af9 > > > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > > > RSP: 002b:00007ffd45e80138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > > > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbda6736af9 > > > RDX: 0000000020000000 RSI: 0000000000008b04 RDI: 0000000000000003 > > > RBP: 00007fbda66faca0 R08: 0000000000000000 R09: 0000000000000000 > > > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbda66fad30 > > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > > </TASK> > > > > I think this is the samiliar problem as what Kees Cook pointed out in > > https://lore.kernel.org/linux-next/202209211250.3049C29@keescook/ > > > > It seems that memcpy() will performs run-time buffer bounds > > checking, which triggers this warning. > > > > #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git > > master > > > > > > diff --git a/include/linux/wireless.h b/include/linux/wireless.h > > index 2d1b54556eff..81603848b0aa 100644 > > --- a/include/linux/wireless.h > > +++ b/include/linux/wireless.h > > @@ -26,7 +26,10 @@ struct compat_iw_point { > > struct __compat_iw_event { > > __u16 len; /* Real length of this stuff */ > > __u16 cmd; /* Wireless IOCTL */ > > - compat_caddr_t pointer; > > + union { > > + compat_caddr_t pointer; > > + __DECLARE_FLEX_ARRAY(__u8, pointer_flex); > > + }; > > Is this expected to be dynamically sized? I assume so, given the "Real > length" comment. :) I think this is dynamically sized. hdr_len = compat_event_type_size[descr->header_type]; event_len = hdr_len + extra_len; [...] /* Add the wireless events in the netlink packet */ nla = nla_reserve(compskb, IFLA_WIRELESS, event_len); if (!nla) { kfree_skb(skb); kfree_skb(compskb); return; } compat_event = nla_data(nla); [...] if (descr->header_type == IW_HEADER_TYPE_POINT) { compat_wrqu.length = wrqu->data.length; compat_wrqu.flags = wrqu->data.flags; memcpy(&compat_event->pointer, ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, hdr_len - IW_EV_COMPAT_LCP_LEN); if (extra_len) memcpy(((char *) compat_event) + hdr_len, extra, extra_len); } else { /* extra_len must be zero, so no if (extra) needed */ memcpy(&compat_event->pointer, wrqu, hdr_len - IW_EV_COMPAT_LCP_LEN); } according to the above code, it seems that this structure is used to parse ths payload from buffer, so the field **pointer** should just be a position label to the unused bytes in buffer. Its unused bytes will be parsed as different structure according to event type. > > > }; > > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > > #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) > > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > > index 76a80a41615b..9d0b50abbe09 100644 > > --- a/net/wireless/wext-core.c > > +++ b/net/wireless/wext-core.c > > @@ -620,7 +620,7 @@ void wireless_send_event(struct net_device * dev, > > adding in more context code: > > memcpy(&compat_event->pointer, > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > hdr_len - IW_EV_COMPAT_LCP_LEN); > if (extra_len) > memcpy(((char *) compat_event) + hdr_len, > extra, extra_len); > > The code above has "pointer" as a memcpy destination as well. I think > that should be changed to pointer_flex as well, as the length calculation > is the same. I wonder what FORTIFY will think about the second memcpy > above. If I'm reading the math correctly, it might need to be: > > if (extra_len) { > size_t offset = hdr_len - offsetof(typeof(*compat_event), pointer_flex); > memcpy(&compat_event->pointer_flex[offset], extra, extra_len); > } > I agree with you. It seems that in this situation, the event type has been cleared, the unuesd bytes start from **pointer** field should be parsed as struct iw_point type as below, which is a bigger structure than **pointer**, it will also triggers the memcpy() warning. /* * The problem for 64/32 bit. * * On 64-bit, a regular event is laid out as follows: * An iw_point event is laid out like this instead: * | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | * | event.len | event.cmd | p a d d i n g | * | iwpnt.len | iwpnt.flg | p a d d i n g | * | extra data ... * * The second padding exists because struct iw_point is extended, * but this depends on the platform... * * On 32-bit, all the padding shouldn't be there. */ And as for the value of offsetof in calculating **offset**, I wonder if we can use the macro defined in include/linux/wireless.h as below, which makes code simplier: #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > > > } else { > > /* extra_len must be zero, so no if (extra) needed */ > > - memcpy(&compat_event->pointer, wrqu, > > + memcpy(&compat_event->pointer_flex, wrqu, > > hdr_len - IW_EV_COMPAT_LCP_LEN); > > } > > > > But otherwise, yes, looks like the right modification. Thanks for tackling > this! It is quite a weird structure! :) > > -Kees > > -- > Kees Cook ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] Add linux-next specific files for 20220923 2022-09-24 11:44 ` Hawkins Jiawei @ 2022-09-24 15:55 ` Hawkins Jiawei 2022-09-24 15:55 ` syzbot 2022-09-24 16:26 ` [PATCH] Add linux-next specific files for 20220923 Kees Cook 0 siblings, 2 replies; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-24 15:55 UTC (permalink / raw) To: yin31149 Cc: 18801353760, davem, edumazet, johannes, keescook, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzbot+473754e5af963cf014cf, syzkaller-bugs Hi, On Sat, 24 Sept 2022 at 19:44, Hawkins Jiawei <yin31149@gmail.com> wrote: > > Hi Kees, > On Sat, 24 Sept 2022 at 15:26, Kees Cook <keescook@chromium.org> wrote: > > > > On Sat, Sep 24, 2022 at 03:10:34PM +0800, Hawkins Jiawei wrote: > > > From: Stephen Rothwell <sfr@canb.auug.org.au> > > > > > > > Hello, > > > > > > > > syzbot found the following issue on: > > > > > > > > HEAD commit: 483fed3b5dc8 Add linux-next specific files for 20220921 > > > > git tree: linux-next > > > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1154ddd5080000 > > > > kernel config: https://syzkaller.appspot.com/x/.config?x=849cb9f70f15b1ba > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf > > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c196f080000 > > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f12618880000 > > > > > > > > Downloadable assets: > > > > disk image: https://storage.googleapis.com/syzbot-assets/1cb3f4618323/disk-483fed3b.raw.xz > > > > vmlinux: https://storage.googleapis.com/syzbot-assets/cc02cb30b495/vmlinux-483fed3b.xz > > > > > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > > > Reported-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com > > > > > > > > ------------[ cut here ]------------ > > > > memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) > > > > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > > > > Modules linked in: > > > > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 > > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022 > > > > RIP: 0010:wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > > > > Code: fa ff ff e8 cd b9 db f8 b9 04 00 00 00 4c 89 e6 48 c7 c2 e0 56 11 8b 48 c7 c7 20 56 11 8b c6 05 94 8e 2a 05 01 e8 b8 b0 a6 00 <0f> 0b e9 9b fa ff ff e8 6f ef 27 f9 e9 a6 fd ff ff e8 c5 ef 27 f9 > > > > RSP: 0018:ffffc90003b2fbc0 EFLAGS: 00010286 > > > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > > > > RDX: ffff888021d157c0 RSI: ffffffff81620348 RDI: fffff52000765f6a > > > > RBP: ffff88801e15c780 R08: 0000000000000005 R09: 0000000000000000 > > > > R10: 0000000080000000 R11: 20676e696e6e6170 R12: 0000000000000008 > > > > R13: ffff888025a72640 R14: ffff8880225d402c R15: ffff8880225d4034 > > > > FS: 0000555556bd9300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 > > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > > CR2: 00007fbda677dfb8 CR3: 000000007b976000 CR4: 00000000003506e0 > > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > > Call Trace: > > > > <TASK> > > > > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 > > > > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 > > > > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] > > > > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] > > > > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 > > > > sock_ioctl+0x285/0x640 net/socket.c:1220 > > > > vfs_ioctl fs/ioctl.c:51 [inline] > > > > __do_sys_ioctl fs/ioctl.c:870 [inline] > > > > __se_sys_ioctl fs/ioctl.c:856 [inline] > > > > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > > > RIP: 0033:0x7fbda6736af9 > > > > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > > > > RSP: 002b:00007ffd45e80138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > > > > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbda6736af9 > > > > RDX: 0000000020000000 RSI: 0000000000008b04 RDI: 0000000000000003 > > > > RBP: 00007fbda66faca0 R08: 0000000000000000 R09: 0000000000000000 > > > > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbda66fad30 > > > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > > > </TASK> > > > > > > I think this is the samiliar problem as what Kees Cook pointed out in > > > https://lore.kernel.org/linux-next/202209211250.3049C29@keescook/ > > > > > > It seems that memcpy() will performs run-time buffer bounds > > > checking, which triggers this warning. > > > > > > #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git > > > master > > > > > > > > > diff --git a/include/linux/wireless.h b/include/linux/wireless.h > > > index 2d1b54556eff..81603848b0aa 100644 > > > --- a/include/linux/wireless.h > > > +++ b/include/linux/wireless.h > > > @@ -26,7 +26,10 @@ struct compat_iw_point { > > > struct __compat_iw_event { > > > __u16 len; /* Real length of this stuff */ > > > __u16 cmd; /* Wireless IOCTL */ > > > - compat_caddr_t pointer; > > > + union { > > > + compat_caddr_t pointer; > > > + __DECLARE_FLEX_ARRAY(__u8, pointer_flex); > > > + }; > > > > Is this expected to be dynamically sized? I assume so, given the "Real > > length" comment. :) > I think this is dynamically sized. > > hdr_len = compat_event_type_size[descr->header_type]; > event_len = hdr_len + extra_len; > > [...] > > /* Add the wireless events in the netlink packet */ > nla = nla_reserve(compskb, IFLA_WIRELESS, event_len); > if (!nla) { > kfree_skb(skb); > kfree_skb(compskb); > return; > } > compat_event = nla_data(nla); > > [...] > > if (descr->header_type == IW_HEADER_TYPE_POINT) { > compat_wrqu.length = wrqu->data.length; > compat_wrqu.flags = wrqu->data.flags; > memcpy(&compat_event->pointer, > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > hdr_len - IW_EV_COMPAT_LCP_LEN); > if (extra_len) > memcpy(((char *) compat_event) + hdr_len, > extra, extra_len); > } else { > /* extra_len must be zero, so no if (extra) needed */ > memcpy(&compat_event->pointer, wrqu, > hdr_len - IW_EV_COMPAT_LCP_LEN); > } > > according to the above code, it seems that this structure is used to > parse ths payload from buffer, so the field **pointer** should just > be a position label to the unused bytes in buffer. Its unused bytes will be > parsed as different structure according to event type. > > > > > > }; > > > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > > > #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) > > > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > > > index 76a80a41615b..9d0b50abbe09 100644 > > > --- a/net/wireless/wext-core.c > > > +++ b/net/wireless/wext-core.c > > > @@ -620,7 +620,7 @@ void wireless_send_event(struct net_device * dev, > > > > adding in more context code: > > > > memcpy(&compat_event->pointer, > > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > > hdr_len - IW_EV_COMPAT_LCP_LEN); > > if (extra_len) > > memcpy(((char *) compat_event) + hdr_len, > > extra, extra_len); > > > > The code above has "pointer" as a memcpy destination as well. I think > > that should be changed to pointer_flex as well, as the length calculation > > is the same. I wonder what FORTIFY will think about the second memcpy > > above. If I'm reading the math correctly, it might need to be: > > > > if (extra_len) { > > size_t offset = hdr_len - offsetof(typeof(*compat_event), pointer_flex); > > memcpy(&compat_event->pointer_flex[offset], extra, extra_len); > > } > > > I agree with you. It seems that in this situation, > the event type has been cleared, the unuesd bytes start from **pointer** > field should be parsed as struct iw_point type as below, which is a bigger > structure than **pointer**, it will also triggers the memcpy() warning. > /* > * The problem for 64/32 bit. > * > * On 64-bit, a regular event is laid out as follows: > * An iw_point event is laid out like this instead: > * | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | > * | event.len | event.cmd | p a d d i n g | > * | iwpnt.len | iwpnt.flg | p a d d i n g | > * | extra data ... > * > * The second padding exists because struct iw_point is extended, > * but this depends on the platform... > * > * On 32-bit, all the padding shouldn't be there. > */ > > And as for the value of offsetof in calculating **offset**, > I wonder if we can use the macro defined in > include/linux/wireless.h as below, which makes code simplier: > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > > > > > > > } else { > > > /* extra_len must be zero, so no if (extra) needed */ > > > - memcpy(&compat_event->pointer, wrqu, > > > + memcpy(&compat_event->pointer_flex, wrqu, > > > hdr_len - IW_EV_COMPAT_LCP_LEN); > > > } > > > > > > > But otherwise, yes, looks like the right modification. Thanks for tackling > > this! It is quite a weird structure! :) > > > > -Kees > > > > -- > > Kees Cook hdr_len = compat_event_type_size[descr->header_type]; event_len = hdr_len + extra_len; [...] /* Add the wireless events in the netlink packet */ nla = nla_reserve(compskb, IFLA_WIRELESS, event_len); if (!nla) { kfree_skb(skb); kfree_skb(compskb); return; } compat_event = nla_data(nla); if (descr->header_type == IW_HEADER_TYPE_POINT) { [...] memcpy(&compat_event->pointer, ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, hdr_len - IW_EV_COMPAT_LCP_LEN); if (extra_len) memcpy(((char *) compat_event) + hdr_len, extra, extra_len); } else { /* extra_len must be zero, so no if (extra) needed */ memcpy(&compat_event->pointer, wrqu, hdr_len - IW_EV_COMPAT_LCP_LEN); } According to above code, it seems that kernel will saves enough memory (hdr_len + extra_len bytes) for payload structure in nla_reserve()(Please correct me if I am wrong), pointed by compat_event. So I wonder if we can use unsafe_memcpy(), to avoid unnecessary memory() check as below, which seems more simple: #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 76a80a41615b..a967da647e2b 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -609,19 +609,26 @@ void wireless_send_event(struct net_device * dev, compat_event->len = event_len; compat_event->cmd = cmd; + + /* kernel reserves event_len's bytes for compat_event, + * so we don't need memcpy()'s bounds check + */ if (descr->header_type == IW_HEADER_TYPE_POINT) { compat_wrqu.length = wrqu->data.length; compat_wrqu.flags = wrqu->data.flags; - memcpy(&compat_event->pointer, + unsafe_memcpy(&compat_event->pointer, ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, - hdr_len - IW_EV_COMPAT_LCP_LEN); + hdr_len - IW_EV_COMPAT_LCP_LEN, + /* compat_event has enough room */); if (extra_len) - memcpy(((char *) compat_event) + hdr_len, - extra, extra_len); + unsafe_memcpy(((char *) compat_event) + hdr_len, + extra, extra_len, + /* compat_event has enough room */); } else { /* extra_len must be zero, so no if (extra) needed */ - memcpy(&compat_event->pointer, wrqu, - hdr_len - IW_EV_COMPAT_LCP_LEN); + unsafe_memcpy(&compat_event->pointer, wrqu, + hdr_len - IW_EV_COMPAT_LCP_LEN, + /* compat_event has enough room */); } nlmsg_end(compskb, nlh); ^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [PATCH] Add linux-next specific files for 20220923 2022-09-24 15:55 ` Hawkins Jiawei @ 2022-09-24 15:55 ` syzbot 2022-09-24 16:13 ` Hawkins Jiawei 2022-09-24 16:26 ` [PATCH] Add linux-next specific files for 20220923 Kees Cook 1 sibling, 1 reply; 18+ messages in thread From: syzbot @ 2022-09-24 15:55 UTC (permalink / raw) To: Hawkins Jiawei Cc: 18801353760, davem, edumazet, johannes, keescook, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzkaller-bugs, yin31149 > Hi, > > On Sat, 24 Sept 2022 at 19:44, Hawkins Jiawei <yin31149@gmail.com> wrote: >> >> Hi Kees, >> On Sat, 24 Sept 2022 at 15:26, Kees Cook <keescook@chromium.org> wrote: >> > >> > On Sat, Sep 24, 2022 at 03:10:34PM +0800, Hawkins Jiawei wrote: >> > > From: Stephen Rothwell <sfr@canb.auug.org.au> >> > > >> > > > Hello, >> > > > >> > > > syzbot found the following issue on: >> > > > >> > > > HEAD commit: 483fed3b5dc8 Add linux-next specific files for 20220921 >> > > > git tree: linux-next >> > > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1154ddd5080000 >> > > > kernel config: https://syzkaller.appspot.com/x/.config?x=849cb9f70f15b1ba >> > > > dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf >> > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 >> > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c196f080000 >> > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f12618880000 >> > > > >> > > > Downloadable assets: >> > > > disk image: https://storage.googleapis.com/syzbot-assets/1cb3f4618323/disk-483fed3b.raw.xz >> > > > vmlinux: https://storage.googleapis.com/syzbot-assets/cc02cb30b495/vmlinux-483fed3b.xz >> > > > >> > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: >> > > > Reported-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com >> > > > >> > > > ------------[ cut here ]------------ >> > > > memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) >> > > > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 >> > > > Modules linked in: >> > > > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 >> > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022 >> > > > RIP: 0010:wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 >> > > > Code: fa ff ff e8 cd b9 db f8 b9 04 00 00 00 4c 89 e6 48 c7 c2 e0 56 11 8b 48 c7 c7 20 56 11 8b c6 05 94 8e 2a 05 01 e8 b8 b0 a6 00 <0f> 0b e9 9b fa ff ff e8 6f ef 27 f9 e9 a6 fd ff ff e8 c5 ef 27 f9 >> > > > RSP: 0018:ffffc90003b2fbc0 EFLAGS: 00010286 >> > > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 >> > > > RDX: ffff888021d157c0 RSI: ffffffff81620348 RDI: fffff52000765f6a >> > > > RBP: ffff88801e15c780 R08: 0000000000000005 R09: 0000000000000000 >> > > > R10: 0000000080000000 R11: 20676e696e6e6170 R12: 0000000000000008 >> > > > R13: ffff888025a72640 R14: ffff8880225d402c R15: ffff8880225d4034 >> > > > FS: 0000555556bd9300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 >> > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> > > > CR2: 00007fbda677dfb8 CR3: 000000007b976000 CR4: 00000000003506e0 >> > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >> > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >> > > > Call Trace: >> > > > <TASK> >> > > > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 >> > > > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 >> > > > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] >> > > > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] >> > > > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 >> > > > sock_ioctl+0x285/0x640 net/socket.c:1220 >> > > > vfs_ioctl fs/ioctl.c:51 [inline] >> > > > __do_sys_ioctl fs/ioctl.c:870 [inline] >> > > > __se_sys_ioctl fs/ioctl.c:856 [inline] >> > > > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 >> > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] >> > > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 >> > > > entry_SYSCALL_64_after_hwframe+0x63/0xcd >> > > > RIP: 0033:0x7fbda6736af9 >> > > > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 >> > > > RSP: 002b:00007ffd45e80138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 >> > > > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbda6736af9 >> > > > RDX: 0000000020000000 RSI: 0000000000008b04 RDI: 0000000000000003 >> > > > RBP: 00007fbda66faca0 R08: 0000000000000000 R09: 0000000000000000 >> > > > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbda66fad30 >> > > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 >> > > > </TASK> >> > > >> > > I think this is the samiliar problem as what Kees Cook pointed out in >> > > https://lore.kernel.org/linux-next/202209211250.3049C29@keescook/ >> > > >> > > It seems that memcpy() will performs run-time buffer bounds >> > > checking, which triggers this warning. >> > > >> > > #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git >> > > master >> > > >> > > >> > > diff --git a/include/linux/wireless.h b/include/linux/wireless.h >> > > index 2d1b54556eff..81603848b0aa 100644 >> > > --- a/include/linux/wireless.h >> > > +++ b/include/linux/wireless.h >> > > @@ -26,7 +26,10 @@ struct compat_iw_point { >> > > struct __compat_iw_event { >> > > __u16 len; /* Real length of this stuff */ >> > > __u16 cmd; /* Wireless IOCTL */ >> > > - compat_caddr_t pointer; >> > > + union { >> > > + compat_caddr_t pointer; >> > > + __DECLARE_FLEX_ARRAY(__u8, pointer_flex); >> > > + }; >> > >> > Is this expected to be dynamically sized? I assume so, given the "Real >> > length" comment. :) >> I think this is dynamically sized. >> >> hdr_len = compat_event_type_size[descr->header_type]; >> event_len = hdr_len + extra_len; >> >> [...] >> >> /* Add the wireless events in the netlink packet */ >> nla = nla_reserve(compskb, IFLA_WIRELESS, event_len); >> if (!nla) { >> kfree_skb(skb); >> kfree_skb(compskb); >> return; >> } >> compat_event = nla_data(nla); >> >> [...] >> >> if (descr->header_type == IW_HEADER_TYPE_POINT) { >> compat_wrqu.length = wrqu->data.length; >> compat_wrqu.flags = wrqu->data.flags; >> memcpy(&compat_event->pointer, >> ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, >> hdr_len - IW_EV_COMPAT_LCP_LEN); >> if (extra_len) >> memcpy(((char *) compat_event) + hdr_len, >> extra, extra_len); >> } else { >> /* extra_len must be zero, so no if (extra) needed */ >> memcpy(&compat_event->pointer, wrqu, >> hdr_len - IW_EV_COMPAT_LCP_LEN); >> } >> >> according to the above code, it seems that this structure is used to >> parse ths payload from buffer, so the field **pointer** should just >> be a position label to the unused bytes in buffer. Its unused bytes will be >> parsed as different structure according to event type. >> >> > >> > > }; >> > > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) >> > > #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) >> > > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c >> > > index 76a80a41615b..9d0b50abbe09 100644 >> > > --- a/net/wireless/wext-core.c >> > > +++ b/net/wireless/wext-core.c >> > > @@ -620,7 +620,7 @@ void wireless_send_event(struct net_device * dev, >> > >> > adding in more context code: >> > >> > memcpy(&compat_event->pointer, >> > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, >> > hdr_len - IW_EV_COMPAT_LCP_LEN); >> > if (extra_len) >> > memcpy(((char *) compat_event) + hdr_len, >> > extra, extra_len); >> > >> > The code above has "pointer" as a memcpy destination as well. I think >> > that should be changed to pointer_flex as well, as the length calculation >> > is the same. I wonder what FORTIFY will think about the second memcpy >> > above. If I'm reading the math correctly, it might need to be: >> > >> > if (extra_len) { >> > size_t offset = hdr_len - offsetof(typeof(*compat_event), pointer_flex); >> > memcpy(&compat_event->pointer_flex[offset], extra, extra_len); >> > } >> > >> I agree with you. It seems that in this situation, >> the event type has been cleared, the unuesd bytes start from **pointer** >> field should be parsed as struct iw_point type as below, which is a bigger >> structure than **pointer**, it will also triggers the memcpy() warning. >> /* >> * The problem for 64/32 bit. >> * >> * On 64-bit, a regular event is laid out as follows: >> * An iw_point event is laid out like this instead: >> * | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | >> * | event.len | event.cmd | p a d d i n g | >> * | iwpnt.len | iwpnt.flg | p a d d i n g | >> * | extra data ... >> * >> * The second padding exists because struct iw_point is extended, >> * but this depends on the platform... >> * >> * On 32-bit, all the padding shouldn't be there. >> */ >> >> And as for the value of offsetof in calculating **offset**, >> I wonder if we can use the macro defined in >> include/linux/wireless.h as below, which makes code simplier: >> #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) >> >> >> > >> > > } else { >> > > /* extra_len must be zero, so no if (extra) needed */ >> > > - memcpy(&compat_event->pointer, wrqu, >> > > + memcpy(&compat_event->pointer_flex, wrqu, >> > > hdr_len - IW_EV_COMPAT_LCP_LEN); >> > > } >> > > >> > >> > But otherwise, yes, looks like the right modification. Thanks for tackling >> > this! It is quite a weird structure! :) >> > >> > -Kees >> > >> > -- >> > Kees Cook > > hdr_len = compat_event_type_size[descr->header_type]; > event_len = hdr_len + extra_len; > > [...] > > /* Add the wireless events in the netlink packet */ > nla = nla_reserve(compskb, IFLA_WIRELESS, event_len); > if (!nla) { > kfree_skb(skb); > kfree_skb(compskb); > return; > } > compat_event = nla_data(nla); > > if (descr->header_type == IW_HEADER_TYPE_POINT) { > [...] > memcpy(&compat_event->pointer, > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > hdr_len - IW_EV_COMPAT_LCP_LEN); > if (extra_len) > memcpy(((char *) compat_event) + hdr_len, > extra, extra_len); > } else { > /* extra_len must be zero, so no if (extra) needed */ > memcpy(&compat_event->pointer, wrqu, > hdr_len - IW_EV_COMPAT_LCP_LEN); > } > > > According to above code, it seems that kernel will saves enough memory > (hdr_len + extra_len bytes) for payload structure in > nla_reserve()(Please correct me if I am wrong), pointed by compat_event. > So I wonder if we can use unsafe_memcpy(), to avoid unnecessary > memory() check as below, which seems more simple: > > #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git want 2 args (repo, branch), got 5 > > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > index 76a80a41615b..a967da647e2b 100644 > --- a/net/wireless/wext-core.c > +++ b/net/wireless/wext-core.c > @@ -609,19 +609,26 @@ void wireless_send_event(struct net_device * dev, > > compat_event->len = event_len; > compat_event->cmd = cmd; > + > + /* kernel reserves event_len's bytes for compat_event, > + * so we don't need memcpy()'s bounds check > + */ > if (descr->header_type == IW_HEADER_TYPE_POINT) { > compat_wrqu.length = wrqu->data.length; > compat_wrqu.flags = wrqu->data.flags; > - memcpy(&compat_event->pointer, > + unsafe_memcpy(&compat_event->pointer, > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > - hdr_len - IW_EV_COMPAT_LCP_LEN); > + hdr_len - IW_EV_COMPAT_LCP_LEN, > + /* compat_event has enough room */); > if (extra_len) > - memcpy(((char *) compat_event) + hdr_len, > - extra, extra_len); > + unsafe_memcpy(((char *) compat_event) + hdr_len, > + extra, extra_len, > + /* compat_event has enough room */); > } else { > /* extra_len must be zero, so no if (extra) needed */ > - memcpy(&compat_event->pointer, wrqu, > - hdr_len - IW_EV_COMPAT_LCP_LEN); > + unsafe_memcpy(&compat_event->pointer, wrqu, > + hdr_len - IW_EV_COMPAT_LCP_LEN, > + /* compat_event has enough room */); > } > > nlmsg_end(compskb, nlh); ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] Add linux-next specific files for 20220923 2022-09-24 15:55 ` syzbot @ 2022-09-24 16:13 ` Hawkins Jiawei 2022-09-24 16:33 ` [syzbot] WARNING in wireless_send_event syzbot 0 siblings, 1 reply; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-24 16:13 UTC (permalink / raw) To: syzbot+473754e5af963cf014cf Cc: 18801353760, davem, edumazet, johannes, keescook, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzkaller-bugs, yin31149 On Sat, 24 Sept 2022 at 23:55, syzbot <syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com> wrote: > > > Hi, > > > > On Sat, 24 Sept 2022 at 19:44, Hawkins Jiawei <yin31149@gmail.com> wrote: > >> > >> Hi Kees, > >> On Sat, 24 Sept 2022 at 15:26, Kees Cook <keescook@chromium.org> wrote: > >> > > >> > On Sat, Sep 24, 2022 at 03:10:34PM +0800, Hawkins Jiawei wrote: > >> > > From: Stephen Rothwell <sfr@canb.auug.org.au> > >> > > > >> > > > Hello, > >> > > > > >> > > > syzbot found the following issue on: > >> > > > > >> > > > HEAD commit: 483fed3b5dc8 Add linux-next specific files for 20220921 > >> > > > git tree: linux-next > >> > > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1154ddd5080000 > >> > > > kernel config: https://syzkaller.appspot.com/x/.config?x=849cb9f70f15b1ba > >> > > > dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf > >> > > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > >> > > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=157c196f080000 > >> > > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11f12618880000 > >> > > > > >> > > > Downloadable assets: > >> > > > disk image: https://storage.googleapis.com/syzbot-assets/1cb3f4618323/disk-483fed3b.raw.xz > >> > > > vmlinux: https://storage.googleapis.com/syzbot-assets/cc02cb30b495/vmlinux-483fed3b.xz > >> > > > > >> > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > >> > > > Reported-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com > >> > > > > >> > > > ------------[ cut here ]------------ > >> > > > memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) > >> > > > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > >> > > > Modules linked in: > >> > > > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 > >> > > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2022 > >> > > > RIP: 0010:wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > >> > > > Code: fa ff ff e8 cd b9 db f8 b9 04 00 00 00 4c 89 e6 48 c7 c2 e0 56 11 8b 48 c7 c7 20 56 11 8b c6 05 94 8e 2a 05 01 e8 b8 b0 a6 00 <0f> 0b e9 9b fa ff ff e8 6f ef 27 f9 e9 a6 fd ff ff e8 c5 ef 27 f9 > >> > > > RSP: 0018:ffffc90003b2fbc0 EFLAGS: 00010286 > >> > > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > >> > > > RDX: ffff888021d157c0 RSI: ffffffff81620348 RDI: fffff52000765f6a > >> > > > RBP: ffff88801e15c780 R08: 0000000000000005 R09: 0000000000000000 > >> > > > R10: 0000000080000000 R11: 20676e696e6e6170 R12: 0000000000000008 > >> > > > R13: ffff888025a72640 R14: ffff8880225d402c R15: ffff8880225d4034 > >> > > > FS: 0000555556bd9300(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 > >> > > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >> > > > CR2: 00007fbda677dfb8 CR3: 000000007b976000 CR4: 00000000003506e0 > >> > > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > >> > > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > >> > > > Call Trace: > >> > > > <TASK> > >> > > > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 > >> > > > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 > >> > > > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] > >> > > > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] > >> > > > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 > >> > > > sock_ioctl+0x285/0x640 net/socket.c:1220 > >> > > > vfs_ioctl fs/ioctl.c:51 [inline] > >> > > > __do_sys_ioctl fs/ioctl.c:870 [inline] > >> > > > __se_sys_ioctl fs/ioctl.c:856 [inline] > >> > > > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > >> > > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > >> > > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > >> > > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > >> > > > RIP: 0033:0x7fbda6736af9 > >> > > > Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 > >> > > > RSP: 002b:00007ffd45e80138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > >> > > > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fbda6736af9 > >> > > > RDX: 0000000020000000 RSI: 0000000000008b04 RDI: 0000000000000003 > >> > > > RBP: 00007fbda66faca0 R08: 0000000000000000 R09: 0000000000000000 > >> > > > R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbda66fad30 > >> > > > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > >> > > > </TASK> > >> > > > >> > > I think this is the samiliar problem as what Kees Cook pointed out in > >> > > https://lore.kernel.org/linux-next/202209211250.3049C29@keescook/ > >> > > > >> > > It seems that memcpy() will performs run-time buffer bounds > >> > > checking, which triggers this warning. > >> > > > >> > > #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git > >> > > master > >> > > > >> > > > >> > > diff --git a/include/linux/wireless.h b/include/linux/wireless.h > >> > > index 2d1b54556eff..81603848b0aa 100644 > >> > > --- a/include/linux/wireless.h > >> > > +++ b/include/linux/wireless.h > >> > > @@ -26,7 +26,10 @@ struct compat_iw_point { > >> > > struct __compat_iw_event { > >> > > __u16 len; /* Real length of this stuff */ > >> > > __u16 cmd; /* Wireless IOCTL */ > >> > > - compat_caddr_t pointer; > >> > > + union { > >> > > + compat_caddr_t pointer; > >> > > + __DECLARE_FLEX_ARRAY(__u8, pointer_flex); > >> > > + }; > >> > > >> > Is this expected to be dynamically sized? I assume so, given the "Real > >> > length" comment. :) > >> I think this is dynamically sized. > >> > >> hdr_len = compat_event_type_size[descr->header_type]; > >> event_len = hdr_len + extra_len; > >> > >> [...] > >> > >> /* Add the wireless events in the netlink packet */ > >> nla = nla_reserve(compskb, IFLA_WIRELESS, event_len); > >> if (!nla) { > >> kfree_skb(skb); > >> kfree_skb(compskb); > >> return; > >> } > >> compat_event = nla_data(nla); > >> > >> [...] > >> > >> if (descr->header_type == IW_HEADER_TYPE_POINT) { > >> compat_wrqu.length = wrqu->data.length; > >> compat_wrqu.flags = wrqu->data.flags; > >> memcpy(&compat_event->pointer, > >> ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > >> hdr_len - IW_EV_COMPAT_LCP_LEN); > >> if (extra_len) > >> memcpy(((char *) compat_event) + hdr_len, > >> extra, extra_len); > >> } else { > >> /* extra_len must be zero, so no if (extra) needed */ > >> memcpy(&compat_event->pointer, wrqu, > >> hdr_len - IW_EV_COMPAT_LCP_LEN); > >> } > >> > >> according to the above code, it seems that this structure is used to > >> parse ths payload from buffer, so the field **pointer** should just > >> be a position label to the unused bytes in buffer. Its unused bytes will be > >> parsed as different structure according to event type. > >> > >> > > >> > > }; > >> > > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > >> > > #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) > >> > > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > >> > > index 76a80a41615b..9d0b50abbe09 100644 > >> > > --- a/net/wireless/wext-core.c > >> > > +++ b/net/wireless/wext-core.c > >> > > @@ -620,7 +620,7 @@ void wireless_send_event(struct net_device * dev, > >> > > >> > adding in more context code: > >> > > >> > memcpy(&compat_event->pointer, > >> > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > >> > hdr_len - IW_EV_COMPAT_LCP_LEN); > >> > if (extra_len) > >> > memcpy(((char *) compat_event) + hdr_len, > >> > extra, extra_len); > >> > > >> > The code above has "pointer" as a memcpy destination as well. I think > >> > that should be changed to pointer_flex as well, as the length calculation > >> > is the same. I wonder what FORTIFY will think about the second memcpy > >> > above. If I'm reading the math correctly, it might need to be: > >> > > >> > if (extra_len) { > >> > size_t offset = hdr_len - offsetof(typeof(*compat_event), pointer_flex); > >> > memcpy(&compat_event->pointer_flex[offset], extra, extra_len); > >> > } > >> > > >> I agree with you. It seems that in this situation, > >> the event type has been cleared, the unuesd bytes start from **pointer** > >> field should be parsed as struct iw_point type as below, which is a bigger > >> structure than **pointer**, it will also triggers the memcpy() warning. > >> /* > >> * The problem for 64/32 bit. > >> * > >> * On 64-bit, a regular event is laid out as follows: > >> * An iw_point event is laid out like this instead: > >> * | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | > >> * | event.len | event.cmd | p a d d i n g | > >> * | iwpnt.len | iwpnt.flg | p a d d i n g | > >> * | extra data ... > >> * > >> * The second padding exists because struct iw_point is extended, > >> * but this depends on the platform... > >> * > >> * On 32-bit, all the padding shouldn't be there. > >> */ > >> > >> And as for the value of offsetof in calculating **offset**, > >> I wonder if we can use the macro defined in > >> include/linux/wireless.h as below, which makes code simplier: > >> #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > >> > >> > >> > > >> > > } else { > >> > > /* extra_len must be zero, so no if (extra) needed */ > >> > > - memcpy(&compat_event->pointer, wrqu, > >> > > + memcpy(&compat_event->pointer_flex, wrqu, > >> > > hdr_len - IW_EV_COMPAT_LCP_LEN); > >> > > } > >> > > > >> > > >> > But otherwise, yes, looks like the right modification. Thanks for tackling > >> > this! It is quite a weird structure! :) > >> > > >> > -Kees > >> > > >> > -- > >> > Kees Cook > > > > hdr_len = compat_event_type_size[descr->header_type]; > > event_len = hdr_len + extra_len; > > > > [...] > > > > /* Add the wireless events in the netlink packet */ > > nla = nla_reserve(compskb, IFLA_WIRELESS, event_len); > > if (!nla) { > > kfree_skb(skb); > > kfree_skb(compskb); > > return; > > } > > compat_event = nla_data(nla); > > > > if (descr->header_type == IW_HEADER_TYPE_POINT) { > > [...] > > memcpy(&compat_event->pointer, > > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > > hdr_len - IW_EV_COMPAT_LCP_LEN); > > if (extra_len) > > memcpy(((char *) compat_event) + hdr_len, > > extra, extra_len); > > } else { > > /* extra_len must be zero, so no if (extra) needed */ > > memcpy(&compat_event->pointer, wrqu, > > hdr_len - IW_EV_COMPAT_LCP_LEN); > > } > > > > > > According to above code, it seems that kernel will saves enough memory > > (hdr_len + extra_len bytes) for payload structure in > > nla_reserve()(Please correct me if I am wrong), pointed by compat_event. > > So I wonder if we can use unsafe_memcpy(), to avoid unnecessary > > memory() check as below, which seems more simple: > > > > #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git > > want 2 args (repo, branch), got 5 > > > > > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > > index 76a80a41615b..a967da647e2b 100644 > > --- a/net/wireless/wext-core.c > > +++ b/net/wireless/wext-core.c > > @@ -609,19 +609,26 @@ void wireless_send_event(struct net_device * dev, > > > > compat_event->len = event_len; > > compat_event->cmd = cmd; > > + > > + /* kernel reserves event_len's bytes for compat_event, > > + * so we don't need memcpy()'s bounds check > > + */ > > if (descr->header_type == IW_HEADER_TYPE_POINT) { > > compat_wrqu.length = wrqu->data.length; > > compat_wrqu.flags = wrqu->data.flags; > > - memcpy(&compat_event->pointer, > > + unsafe_memcpy(&compat_event->pointer, > > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > > - hdr_len - IW_EV_COMPAT_LCP_LEN); > > + hdr_len - IW_EV_COMPAT_LCP_LEN, > > + /* compat_event has enough room */); > > if (extra_len) > > - memcpy(((char *) compat_event) + hdr_len, > > - extra, extra_len); > > + unsafe_memcpy(((char *) compat_event) + hdr_len, > > + extra, extra_len, > > + /* compat_event has enough room */); > > } else { > > /* extra_len must be zero, so no if (extra) needed */ > > - memcpy(&compat_event->pointer, wrqu, > > - hdr_len - IW_EV_COMPAT_LCP_LEN); > > + unsafe_memcpy(&compat_event->pointer, wrqu, > > + hdr_len - IW_EV_COMPAT_LCP_LEN, > > + /* compat_event has enough room */); > > } > > > > nlmsg_end(compskb, nlh); #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 76a80a41615b..a967da647e2b 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -609,19 +609,26 @@ void wireless_send_event(struct net_device * dev, compat_event->len = event_len; compat_event->cmd = cmd; + + /* kernel reserves event_len's bytes for compat_event, + * so we don't need memcpy()'s bounds check + */ if (descr->header_type == IW_HEADER_TYPE_POINT) { compat_wrqu.length = wrqu->data.length; compat_wrqu.flags = wrqu->data.flags; - memcpy(&compat_event->pointer, + unsafe_memcpy(&compat_event->pointer, ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, - hdr_len - IW_EV_COMPAT_LCP_LEN); + hdr_len - IW_EV_COMPAT_LCP_LEN, + /* compat_event has enough room */); if (extra_len) - memcpy(((char *) compat_event) + hdr_len, - extra, extra_len); + unsafe_memcpy(((char *) compat_event) + hdr_len, + extra, extra_len, + /* compat_event has enough room */); } else { /* extra_len must be zero, so no if (extra) needed */ - memcpy(&compat_event->pointer, wrqu, - hdr_len - IW_EV_COMPAT_LCP_LEN); + unsafe_memcpy(&compat_event->pointer, wrqu, + hdr_len - IW_EV_COMPAT_LCP_LEN, + /* compat_event has enough room */); } nlmsg_end(compskb, nlh); ^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [syzbot] WARNING in wireless_send_event 2022-09-24 16:13 ` Hawkins Jiawei @ 2022-09-24 16:33 ` syzbot 0 siblings, 0 replies; 18+ messages in thread From: syzbot @ 2022-09-24 16:33 UTC (permalink / raw) To: 18801353760, davem, edumazet, johannes, keescook, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzkaller-bugs, yin31149 Hello, syzbot tried to test the proposed patch but the build/boot failed: failed to create VM pool: failed to create GCE image: create image operation failed: &{Code:PERMISSIONS_ERROR ErrorDetails:[] Location: Message:Required 'read' permission for 'disks/ci-upstream-linux-next-kasan-gce-root-test-job-test-job-image.tar.gz' ForceSendFields:[] NullFields:[]}. syzkaller build log: go env (err=<nil>) GO111MODULE="auto" GOARCH="amd64" GOBIN="" GOCACHE="/syzkaller/.cache/go-build" GOENV="/syzkaller/.config/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="/syzkaller/jobs/linux/gopath/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="linux" GOPATH="/syzkaller/jobs/linux/gopath" GOPRIVATE="" GOPROXY="https://proxy.golang.org,direct" GOROOT="/usr/local/go" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64" GOVCS="" GOVERSION="go1.17" GCCGO="gccgo" AR="ar" CC="gcc" CXX="g++" CGO_ENABLED="1" GOMOD="/syzkaller/jobs/linux/gopath/src/github.com/google/syzkaller/go.mod" CGO_CFLAGS="-g -O2" CGO_CPPFLAGS="" CGO_CXXFLAGS="-g -O2" CGO_FFLAGS="-g -O2" CGO_LDFLAGS="-g -O2" PKG_CONFIG="pkg-config" GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build4239397487=/tmp/go-build -gno-record-gcc-switches" git status (err=<nil>) HEAD detached at 380f82fb6 nothing to commit, working tree clean go list -f '{{.Stale}}' ./sys/syz-sysgen | grep -q false || go install ./sys/syz-sysgen make .descriptions bin/syz-sysgen touch .descriptions GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=380f82fb6ebefdaa2b4e4f84d34a9019900f0b89 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20220921-114622'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-fuzzer github.com/google/syzkaller/syz-fuzzer GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=380f82fb6ebefdaa2b4e4f84d34a9019900f0b89 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20220921-114622'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-execprog github.com/google/syzkaller/tools/syz-execprog GOOS=linux GOARCH=amd64 go build "-ldflags=-s -w -X github.com/google/syzkaller/prog.GitRevision=380f82fb6ebefdaa2b4e4f84d34a9019900f0b89 -X 'github.com/google/syzkaller/prog.gitRevisionDate=20220921-114622'" "-tags=syz_target syz_os_linux syz_arch_amd64 " -o ./bin/linux_amd64/syz-stress github.com/google/syzkaller/tools/syz-stress mkdir -p ./bin/linux_amd64 gcc -o ./bin/linux_amd64/syz-executor executor/executor.cc \ -m64 -O2 -pthread -Wall -Werror -Wparentheses -Wunused-const-variable -Wframe-larger-than=16384 -Wno-stringop-overflow -Wno-array-bounds -Wno-format-overflow -static-pie -fpermissive -w -DGOOS_linux=1 -DGOARCH_amd64=1 \ -DHOSTGOOS_linux=1 -DGIT_REVISION=\"380f82fb6ebefdaa2b4e4f84d34a9019900f0b89\" Tested on: commit: aaa11ce2 Add linux-next specific files for 20220923 git tree: linux-next kernel config: https://syzkaller.appspot.com/x/.config?x=186d1ff305f10294 dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 patch: https://syzkaller.appspot.com/x/patch.diff?x=15585edf080000 ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] Add linux-next specific files for 20220923 2022-09-24 15:55 ` Hawkins Jiawei 2022-09-24 15:55 ` syzbot @ 2022-09-24 16:26 ` Kees Cook 2022-09-25 6:25 ` Hawkins Jiawei 1 sibling, 1 reply; 18+ messages in thread From: Kees Cook @ 2022-09-24 16:26 UTC (permalink / raw) To: Hawkins Jiawei Cc: 18801353760, davem, edumazet, johannes, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzbot+473754e5af963cf014cf, syzkaller-bugs On Sat, Sep 24, 2022 at 11:55:14PM +0800, Hawkins Jiawei wrote: > > And as for the value of offsetof in calculating **offset**, > > I wonder if we can use the macro defined in > > include/linux/wireless.h as below, which makes code simplier: > > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) Ah yes, that would be good. > According to above code, it seems that kernel will saves enough memory > (hdr_len + extra_len bytes) for payload structure in > nla_reserve()(Please correct me if I am wrong), pointed by compat_event. > So I wonder if we can use unsafe_memcpy(), to avoid unnecessary > memcpy() check as below, which seems more simple: I'd rather this was properly resolved with the creation of a real flexible array so that when bounds tracking gets improved in the future, the compiler can reason about it better. And, I think, it makes the code more readable: diff --git a/include/linux/wireless.h b/include/linux/wireless.h index 2d1b54556eff..e0b4b46da63f 100644 --- a/include/linux/wireless.h +++ b/include/linux/wireless.h @@ -26,7 +26,10 @@ struct compat_iw_point { struct __compat_iw_event { __u16 len; /* Real length of this stuff */ __u16 cmd; /* Wireless IOCTL */ - compat_caddr_t pointer; + union { + compat_caddr_t pointer; + DECLARE_FLEX_ARRAY(__u8, ptr_bytes); + }; }; #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 76a80a41615b..6079c8f4b634 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -468,6 +468,7 @@ void wireless_send_event(struct net_device * dev, struct __compat_iw_event *compat_event; struct compat_iw_point compat_wrqu; struct sk_buff *compskb; + int ptr_len; #endif /* @@ -582,6 +583,7 @@ void wireless_send_event(struct net_device * dev, nlmsg_end(skb, nlh); #ifdef CONFIG_COMPAT hdr_len = compat_event_type_size[descr->header_type]; + ptr_len = hdr_len - IW_EV_COMPAT_LCP_LEN; event_len = hdr_len + extra_len; compskb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); @@ -612,16 +614,15 @@ void wireless_send_event(struct net_device * dev, if (descr->header_type == IW_HEADER_TYPE_POINT) { compat_wrqu.length = wrqu->data.length; compat_wrqu.flags = wrqu->data.flags; - memcpy(&compat_event->pointer, + memcpy(compat_event->ptr_bytes, ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, - hdr_len - IW_EV_COMPAT_LCP_LEN); + ptr_len); if (extra_len) - memcpy(((char *) compat_event) + hdr_len, + memcpy(compat_event->ptr_bytes + ptr_len, extra, extra_len); } else { /* extra_len must be zero, so no if (extra) needed */ - memcpy(&compat_event->pointer, wrqu, - hdr_len - IW_EV_COMPAT_LCP_LEN); + memcpy(compat_event->ptr_bytes, wrqu, ptr_len); } nlmsg_end(compskb, nlh); -- Kees Cook ^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [PATCH] Add linux-next specific files for 20220923 2022-09-24 16:26 ` [PATCH] Add linux-next specific files for 20220923 Kees Cook @ 2022-09-25 6:25 ` Hawkins Jiawei 0 siblings, 0 replies; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-25 6:25 UTC (permalink / raw) To: keescook Cc: 18801353760, davem, edumazet, johannes, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzbot+473754e5af963cf014cf, syzkaller-bugs, yin31149 On Sun, 25 Sept 2022 at 00:26, Kees Cook <keescook@chromium.org> wrote: > > On Sat, Sep 24, 2022 at 11:55:14PM +0800, Hawkins Jiawei wrote: > > > And as for the value of offsetof in calculating **offset**, > > > I wonder if we can use the macro defined in > > > include/linux/wireless.h as below, which makes code simplier: > > > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > > Ah yes, that would be good. > > > According to above code, it seems that kernel will saves enough memory > > (hdr_len + extra_len bytes) for payload structure in > > nla_reserve()(Please correct me if I am wrong), pointed by compat_event. > > So I wonder if we can use unsafe_memcpy(), to avoid unnecessary > > memcpy() check as below, which seems more simple: > > I'd rather this was properly resolved with the creation of a real > flexible array so that when bounds tracking gets improved in the future, > the compiler can reason about it better. And, I think, it makes the code > more readable: > > diff --git a/include/linux/wireless.h b/include/linux/wireless.h > index 2d1b54556eff..e0b4b46da63f 100644 > --- a/include/linux/wireless.h > +++ b/include/linux/wireless.h > @@ -26,7 +26,10 @@ struct compat_iw_point { > struct __compat_iw_event { > __u16 len; /* Real length of this stuff */ > __u16 cmd; /* Wireless IOCTL */ > - compat_caddr_t pointer; > + union { > + compat_caddr_t pointer; > + DECLARE_FLEX_ARRAY(__u8, ptr_bytes); > + }; > }; > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > index 76a80a41615b..6079c8f4b634 100644 > --- a/net/wireless/wext-core.c > +++ b/net/wireless/wext-core.c > @@ -468,6 +468,7 @@ void wireless_send_event(struct net_device * dev, > struct __compat_iw_event *compat_event; > struct compat_iw_point compat_wrqu; > struct sk_buff *compskb; > + int ptr_len; > #endif > > /* > @@ -582,6 +583,7 @@ void wireless_send_event(struct net_device * dev, > nlmsg_end(skb, nlh); > #ifdef CONFIG_COMPAT > hdr_len = compat_event_type_size[descr->header_type]; > + ptr_len = hdr_len - IW_EV_COMPAT_LCP_LEN; > event_len = hdr_len + extra_len; > > compskb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); > @@ -612,16 +614,15 @@ void wireless_send_event(struct net_device * dev, > if (descr->header_type == IW_HEADER_TYPE_POINT) { > compat_wrqu.length = wrqu->data.length; > compat_wrqu.flags = wrqu->data.flags; > - memcpy(&compat_event->pointer, > + memcpy(compat_event->ptr_bytes, > ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > - hdr_len - IW_EV_COMPAT_LCP_LEN); > + ptr_len); > if (extra_len) > - memcpy(((char *) compat_event) + hdr_len, > + memcpy(compat_event->ptr_bytes + ptr_len, > extra, extra_len); > } else { > /* extra_len must be zero, so no if (extra) needed */ > - memcpy(&compat_event->pointer, wrqu, > - hdr_len - IW_EV_COMPAT_LCP_LEN); > + memcpy(compat_event->ptr_bytes, wrqu, ptr_len); > } > > nlmsg_end(compskb, nlh); > > > -- > Kees Cook Yes, it seems that this code is more readable. I will refactor the patch in this way, with some comments on union in struct compat_iw_point. By the way, do you think we need to refactor the **struct compat_iw_point** into union with some comments, or just replace the **pointer** field with **DECLARE_FLEX_ARRAY(__u8, ptr_bytes)**? Because it seems that this field is only used in wireless_send_event() and some macros in this include/linux/wireless.h ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [syzbot] WARNING in wireless_send_event 2022-09-24 7:10 ` [PATCH] Add linux-next specific files for 20220923 Hawkins Jiawei 2022-09-24 7:26 ` Kees Cook @ 2022-09-24 7:32 ` syzbot 1 sibling, 0 replies; 18+ messages in thread From: syzbot @ 2022-09-24 7:32 UTC (permalink / raw) To: 18801353760, davem, edumazet, johannes, keescook, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzkaller-bugs, yin31149 Hello, syzbot has tested the proposed patch and the reproducer did not trigger any issue: Reported-and-tested-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com Tested on: commit: aaa11ce2 Add linux-next specific files for 20220923 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=13b03250880000 kernel config: https://syzkaller.appspot.com/x/.config?x=186d1ff305f10294 dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 patch: https://syzkaller.appspot.com/x/patch.diff?x=11b03250880000 Note: testing is done by a robot and is best-effort only. ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [syzbot] WARNING in wireless_send_event 2022-09-23 16:05 [syzbot] WARNING in wireless_send_event syzbot 2022-09-24 7:10 ` [PATCH] Add linux-next specific files for 20220923 Hawkins Jiawei @ 2022-09-26 11:59 ` Hawkins Jiawei 2022-09-26 12:24 ` syzbot 2022-09-26 15:09 ` [PATCH] wext: use flex array destination for memcpy() Hawkins Jiawei 2022-09-26 23:34 ` [PATCH wireless-next v2] " Hawkins Jiawei 3 siblings, 1 reply; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-26 11:59 UTC (permalink / raw) To: syzbot+473754e5af963cf014cf Cc: 18801353760, davem, edumazet, johannes, keescook, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzkaller-bugs, yin31149 #syz test git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git aaa11ce2ffc84166d11c4d2ac88c3fcf75425fbd Syzkaller reports refcount bug as follows: ------------[ cut here ]------------ memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 Modules linked in: CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 [...] Call Trace: <TASK> ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 sock_ioctl+0x285/0x640 net/socket.c:1220 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] </TASK> Wireless events will be sent on the appropriate channels in wireless_send_event(). Different wireless events may have different payload structure and size, so kernel uses **len** and **cmd** field in struct __compat_iw_event as wireless event common LCP part, uses **pointer** as a label to mark the position of remaining different part. Yet the problem is that, **pointer** is a compat_caddr_t type, which may be smaller than the relative structure at the same position. So during wireless_send_event() tries to parse the wireless events payload, it may trigger the memcpy() run-time destination buffer bounds checking when the relative structure's data is copied to the position marked by **pointer**. This patch solves it by introducing flexible-array field **ptr_bytes**, to mark the position of the wireless events remaining part next to LCP part. What's more, this patch also adds **ptr_len** variable in wireless_send_event() to improve its maintainability. Link: https://lore.kernel.org/all/00000000000070db2005e95a5984@google.com/ Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com> --- include/linux/wireless.h | 10 +++++++++- net/wireless/wext-core.c | 13 ++++++++----- 2 files changed, 17 insertions(+), 6 deletions(-) diff --git a/include/linux/wireless.h b/include/linux/wireless.h index 2d1b54556eff..e6e34d74dda0 100644 --- a/include/linux/wireless.h +++ b/include/linux/wireless.h @@ -26,7 +26,15 @@ struct compat_iw_point { struct __compat_iw_event { __u16 len; /* Real length of this stuff */ __u16 cmd; /* Wireless IOCTL */ - compat_caddr_t pointer; + + union { + compat_caddr_t pointer; + + /* we need ptr_bytes to make memcpy() run-time destination + * buffer bounds checking happy, nothing special + */ + DECLARE_FLEX_ARRAY(__u8, ptr_bytes); + }; }; #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 76a80a41615b..2ca009aca865 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -468,6 +468,7 @@ void wireless_send_event(struct net_device * dev, struct __compat_iw_event *compat_event; struct compat_iw_point compat_wrqu; struct sk_buff *compskb; + int ptr_len; #endif /* @@ -582,6 +583,9 @@ void wireless_send_event(struct net_device * dev, nlmsg_end(skb, nlh); #ifdef CONFIG_COMPAT hdr_len = compat_event_type_size[descr->header_type]; + + /* ptr_len is remaining size in event header apart from LCP */ + ptr_len = hdr_len - IW_EV_COMPAT_LCP_LEN; event_len = hdr_len + extra_len; compskb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); @@ -612,16 +616,15 @@ void wireless_send_event(struct net_device * dev, if (descr->header_type == IW_HEADER_TYPE_POINT) { compat_wrqu.length = wrqu->data.length; compat_wrqu.flags = wrqu->data.flags; - memcpy(&compat_event->pointer, + memcpy(compat_event->ptr_bytes, ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, - hdr_len - IW_EV_COMPAT_LCP_LEN); + ptr_len); if (extra_len) - memcpy(((char *) compat_event) + hdr_len, + memcpy(&compat_event->ptr_bytes[ptr_len], extra, extra_len); } else { /* extra_len must be zero, so no if (extra) needed */ - memcpy(&compat_event->pointer, wrqu, - hdr_len - IW_EV_COMPAT_LCP_LEN); + memcpy(compat_event->ptr_bytes, wrqu, ptr_len); } nlmsg_end(compskb, nlh); -- 2.25.1 ^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [syzbot] WARNING in wireless_send_event 2022-09-26 11:59 ` Hawkins Jiawei @ 2022-09-26 12:24 ` syzbot 0 siblings, 0 replies; 18+ messages in thread From: syzbot @ 2022-09-26 12:24 UTC (permalink / raw) To: 18801353760, davem, edumazet, johannes, keescook, kuba, linux-kernel, linux-wireless, netdev, pabeni, sfr, syzkaller-bugs, yin31149 Hello, syzbot has tested the proposed patch and the reproducer did not trigger any issue: Reported-and-tested-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com Tested on: commit: aaa11ce2 Add linux-next specific files for 20220923 git tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git console output: https://syzkaller.appspot.com/x/log.txt?x=1490566c880000 kernel config: https://syzkaller.appspot.com/x/.config?x=186d1ff305f10294 dashboard link: https://syzkaller.appspot.com/bug?extid=473754e5af963cf014cf compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 patch: https://syzkaller.appspot.com/x/patch.diff?x=162cc9e4880000 Note: testing is done by a robot and is best-effort only. ^ permalink raw reply [flat|nested] 18+ messages in thread
* [PATCH] wext: use flex array destination for memcpy() 2022-09-23 16:05 [syzbot] WARNING in wireless_send_event syzbot 2022-09-24 7:10 ` [PATCH] Add linux-next specific files for 20220923 Hawkins Jiawei 2022-09-26 11:59 ` Hawkins Jiawei @ 2022-09-26 15:09 ` Hawkins Jiawei 2022-09-26 16:14 ` Eric Dumazet 2022-09-26 17:43 ` Kees Cook 2022-09-26 23:34 ` [PATCH wireless-next v2] " Hawkins Jiawei 3 siblings, 2 replies; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-26 15:09 UTC (permalink / raw) To: syzbot+473754e5af963cf014cf, Johannes Berg, David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni Cc: linux-kernel, linux-wireless, netdev, syzkaller-bugs, 18801353760, yin31149, Kees Cook Syzkaller reports refcount bug as follows: ------------[ cut here ]------------ memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 Modules linked in: CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 [...] Call Trace: <TASK> ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 sock_ioctl+0x285/0x640 net/socket.c:1220 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] </TASK> Wireless events will be sent on the appropriate channels in wireless_send_event(). Different wireless events may have different payload structure and size, so kernel uses **len** and **cmd** field in struct __compat_iw_event as wireless event common LCP part, uses **pointer** as a label to mark the position of remaining different part. Yet the problem is that, **pointer** is a compat_caddr_t type, which may be smaller than the relative structure at the same position. So during wireless_send_event() tries to parse the wireless events payload, it may trigger the memcpy() run-time destination buffer bounds checking when the relative structure's data is copied to the position marked by **pointer**. This patch solves it by introducing flexible-array field **ptr_bytes**, to mark the position of the wireless events remaining part next to LCP part. What's more, this patch also adds **ptr_len** variable in wireless_send_event() to improve its maintainability. Reported-and-tested-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/00000000000070db2005e95a5984@google.com/ Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com> --- include/linux/wireless.h | 10 +++++++++- net/wireless/wext-core.c | 17 ++++++++++------- 2 files changed, 19 insertions(+), 8 deletions(-) diff --git a/include/linux/wireless.h b/include/linux/wireless.h index 2d1b54556eff..e6e34d74dda0 100644 --- a/include/linux/wireless.h +++ b/include/linux/wireless.h @@ -26,7 +26,15 @@ struct compat_iw_point { struct __compat_iw_event { __u16 len; /* Real length of this stuff */ __u16 cmd; /* Wireless IOCTL */ - compat_caddr_t pointer; + + union { + compat_caddr_t pointer; + + /* we need ptr_bytes to make memcpy() run-time destination + * buffer bounds checking happy, nothing special + */ + DECLARE_FLEX_ARRAY(__u8, ptr_bytes); + }; }; #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 76a80a41615b..fe8765c4075d 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -468,6 +468,7 @@ void wireless_send_event(struct net_device * dev, struct __compat_iw_event *compat_event; struct compat_iw_point compat_wrqu; struct sk_buff *compskb; + int ptr_len; #endif /* @@ -582,6 +583,9 @@ void wireless_send_event(struct net_device * dev, nlmsg_end(skb, nlh); #ifdef CONFIG_COMPAT hdr_len = compat_event_type_size[descr->header_type]; + + /* ptr_len is remaining size in event header apart from LCP */ + ptr_len = hdr_len - IW_EV_COMPAT_LCP_LEN; event_len = hdr_len + extra_len; compskb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); @@ -612,16 +616,15 @@ void wireless_send_event(struct net_device * dev, if (descr->header_type == IW_HEADER_TYPE_POINT) { compat_wrqu.length = wrqu->data.length; compat_wrqu.flags = wrqu->data.flags; - memcpy(&compat_event->pointer, - ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, - hdr_len - IW_EV_COMPAT_LCP_LEN); + memcpy(compat_event->ptr_bytes, + ((char *)&compat_wrqu) + IW_EV_COMPAT_POINT_OFF, + ptr_len); if (extra_len) - memcpy(((char *) compat_event) + hdr_len, - extra, extra_len); + memcpy(&compat_event->ptr_bytes[ptr_len], + extra, extra_len); } else { /* extra_len must be zero, so no if (extra) needed */ - memcpy(&compat_event->pointer, wrqu, - hdr_len - IW_EV_COMPAT_LCP_LEN); + memcpy(compat_event->ptr_bytes, wrqu, ptr_len); } nlmsg_end(compskb, nlh); -- 2.25.1 ^ permalink raw reply related [flat|nested] 18+ messages in thread
* Re: [PATCH] wext: use flex array destination for memcpy() 2022-09-26 15:09 ` [PATCH] wext: use flex array destination for memcpy() Hawkins Jiawei @ 2022-09-26 16:14 ` Eric Dumazet 2022-09-26 23:17 ` Hawkins Jiawei 2022-09-26 17:43 ` Kees Cook 1 sibling, 1 reply; 18+ messages in thread From: Eric Dumazet @ 2022-09-26 16:14 UTC (permalink / raw) To: Hawkins Jiawei Cc: syzbot+473754e5af963cf014cf, Johannes Berg, David S. Miller, Jakub Kicinski, Paolo Abeni, LKML, linux-wireless, netdev, syzkaller-bugs, 18801353760, Kees Cook On Mon, Sep 26, 2022 at 8:09 AM Hawkins Jiawei <yin31149@gmail.com> wrote: > > Syzkaller reports refcount bug as follows: This has nothing to do with a refcount bug... > ------------[ cut here ]------------ > memcpy: detected field-spanning write (size 8) of single field > "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 > wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > Modules linked in: > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted > 6.0.0-rc6-next-20220921-syzkaller #0 > [...] > Call Trace: > <TASK> > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 > sock_ioctl+0x285/0x640 net/socket.c:1220 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:870 [inline] > __se_sys_ioctl fs/ioctl.c:856 [inline] > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > [...] > </TASK> > > Wireless events will be sent on the appropriate channels in > wireless_send_event(). Different wireless events may have different > payload structure and size, so kernel uses **len** and **cmd** field > in struct __compat_iw_event as wireless event common LCP part, uses > **pointer** as a label to mark the position of remaining different part. > > Yet the problem is that, **pointer** is a compat_caddr_t type, which may > be smaller than the relative structure at the same position. So during > wireless_send_event() tries to parse the wireless events payload, it may > trigger the memcpy() run-time destination buffer bounds checking when the > relative structure's data is copied to the position marked by **pointer**. > > This patch solves it by introducing flexible-array field **ptr_bytes**, > to mark the position of the wireless events remaining part next to > LCP part. What's more, this patch also adds **ptr_len** variable in > wireless_send_event() to improve its maintainability. > > Reported-and-tested-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com > Link: https://lore.kernel.org/all/00000000000070db2005e95a5984@google.com/ > Suggested-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Hawkins Jiawei <yin31149@gmail.com> > --- > include/linux/wireless.h | 10 +++++++++- > net/wireless/wext-core.c | 17 ++++++++++------- > 2 files changed, 19 insertions(+), 8 deletions(-) > > diff --git a/include/linux/wireless.h b/include/linux/wireless.h > index 2d1b54556eff..e6e34d74dda0 100644 > --- a/include/linux/wireless.h > +++ b/include/linux/wireless.h > @@ -26,7 +26,15 @@ struct compat_iw_point { > struct __compat_iw_event { > __u16 len; /* Real length of this stuff */ > __u16 cmd; /* Wireless IOCTL */ > - compat_caddr_t pointer; > + > + union { > + compat_caddr_t pointer; > + > + /* we need ptr_bytes to make memcpy() run-time destination > + * buffer bounds checking happy, nothing special > + */ > + DECLARE_FLEX_ARRAY(__u8, ptr_bytes); > + }; > }; > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > index 76a80a41615b..fe8765c4075d 100644 > --- a/net/wireless/wext-core.c > +++ b/net/wireless/wext-core.c > @@ -468,6 +468,7 @@ void wireless_send_event(struct net_device * dev, > struct __compat_iw_event *compat_event; > struct compat_iw_point compat_wrqu; > struct sk_buff *compskb; > + int ptr_len; > #endif > > /* > @@ -582,6 +583,9 @@ void wireless_send_event(struct net_device * dev, > nlmsg_end(skb, nlh); > #ifdef CONFIG_COMPAT > hdr_len = compat_event_type_size[descr->header_type]; > + > + /* ptr_len is remaining size in event header apart from LCP */ > + ptr_len = hdr_len - IW_EV_COMPAT_LCP_LEN; > event_len = hdr_len + extra_len; > > compskb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); > @@ -612,16 +616,15 @@ void wireless_send_event(struct net_device * dev, > if (descr->header_type == IW_HEADER_TYPE_POINT) { > compat_wrqu.length = wrqu->data.length; > compat_wrqu.flags = wrqu->data.flags; > - memcpy(&compat_event->pointer, > - ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > - hdr_len - IW_EV_COMPAT_LCP_LEN); > + memcpy(compat_event->ptr_bytes, > + ((char *)&compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > + ptr_len); > if (extra_len) > - memcpy(((char *) compat_event) + hdr_len, > - extra, extra_len); > + memcpy(&compat_event->ptr_bytes[ptr_len], > + extra, extra_len); > } else { > /* extra_len must be zero, so no if (extra) needed */ > - memcpy(&compat_event->pointer, wrqu, > - hdr_len - IW_EV_COMPAT_LCP_LEN); > + memcpy(compat_event->ptr_bytes, wrqu, ptr_len); > } > > nlmsg_end(compskb, nlh); > -- > 2.25.1 > ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] wext: use flex array destination for memcpy() 2022-09-26 16:14 ` Eric Dumazet @ 2022-09-26 23:17 ` Hawkins Jiawei 0 siblings, 0 replies; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-26 23:17 UTC (permalink / raw) To: edumazet Cc: 18801353760, davem, johannes, keescook, kuba, linux-kernel, linux-wireless, netdev, pabeni, syzbot+473754e5af963cf014cf, syzkaller-bugs, yin31149 On Tue, 27 Sept 2022 at 00:14, Eric Dumazet <edumazet@google.com> wrote: > > On Mon, Sep 26, 2022 at 8:09 AM Hawkins Jiawei <yin31149@gmail.com> wrote: > > > > Syzkaller reports refcount bug as follows: > > This has nothing to do with a refcount bug... Sorry for my typo error, it should be a "buffer overflow false positive" bug as Kees Cook points out. I will correct it in my v2 patch. > > > ------------[ cut here ]------------ > > > > memcpy: detected field-spanning write (size 8) of single field > > "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) > > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 > > wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > > Modules linked in: > > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted > > 6.0.0-rc6-next-20220921-syzkaller #0 > > [...] > > Call Trace: > > <TASK> > > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 > > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 > > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] > > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] > > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 > > sock_ioctl+0x285/0x640 net/socket.c:1220 > > vfs_ioctl fs/ioctl.c:51 [inline] > > __do_sys_ioctl fs/ioctl.c:870 [inline] > > __se_sys_ioctl fs/ioctl.c:856 [inline] > > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > [...] > > </TASK> > > > > Wireless events will be sent on the appropriate channels in > > wireless_send_event(). Different wireless events may have different > > payload structure and size, so kernel uses **len** and **cmd** field > > in struct __compat_iw_event as wireless event common LCP part, uses > > **pointer** as a label to mark the position of remaining different part. > > > > Yet the problem is that, **pointer** is a compat_caddr_t type, which may > > be smaller than the relative structure at the same position. So during > > wireless_send_event() tries to parse the wireless events payload, it may > > trigger the memcpy() run-time destination buffer bounds checking when the > > relative structure's data is copied to the position marked by **pointer**. > > > > This patch solves it by introducing flexible-array field **ptr_bytes**, > > to mark the position of the wireless events remaining part next to > > LCP part. What's more, this patch also adds **ptr_len** variable in > > wireless_send_event() to improve its maintainability. > > > > Reported-and-tested-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com > > Link: https://lore.kernel.org/all/00000000000070db2005e95a5984@google.com/ > > Suggested-by: Kees Cook <keescook@chromium.org> > > Signed-off-by: Hawkins Jiawei <yin31149@gmail.com> > > --- > > include/linux/wireless.h | 10 +++++++++- > > net/wireless/wext-core.c | 17 ++++++++++------- > > 2 files changed, 19 insertions(+), 8 deletions(-) > > > > diff --git a/include/linux/wireless.h b/include/linux/wireless.h > > index 2d1b54556eff..e6e34d74dda0 100644 > > --- a/include/linux/wireless.h > > +++ b/include/linux/wireless.h > > @@ -26,7 +26,15 @@ struct compat_iw_point { > > struct __compat_iw_event { > > __u16 len; /* Real length of this stuff */ > > __u16 cmd; /* Wireless IOCTL */ > > - compat_caddr_t pointer; > > + > > + union { > > + compat_caddr_t pointer; > > + > > + /* we need ptr_bytes to make memcpy() run-time destination > > + * buffer bounds checking happy, nothing special > > + */ > > + DECLARE_FLEX_ARRAY(__u8, ptr_bytes); > > + }; > > }; > > #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) > > #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) > > diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c > > index 76a80a41615b..fe8765c4075d 100644 > > --- a/net/wireless/wext-core.c > > +++ b/net/wireless/wext-core.c > > @@ -468,6 +468,7 @@ void wireless_send_event(struct net_device * dev, > > struct __compat_iw_event *compat_event; > > struct compat_iw_point compat_wrqu; > > struct sk_buff *compskb; > > + int ptr_len; > > #endif > > > > /* > > @@ -582,6 +583,9 @@ void wireless_send_event(struct net_device * dev, > > nlmsg_end(skb, nlh); > > #ifdef CONFIG_COMPAT > > hdr_len = compat_event_type_size[descr->header_type]; > > + > > + /* ptr_len is remaining size in event header apart from LCP */ > > + ptr_len = hdr_len - IW_EV_COMPAT_LCP_LEN; > > event_len = hdr_len + extra_len; > > > > compskb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); > > @@ -612,16 +616,15 @@ void wireless_send_event(struct net_device * dev, > > if (descr->header_type == IW_HEADER_TYPE_POINT) { > > compat_wrqu.length = wrqu->data.length; > > compat_wrqu.flags = wrqu->data.flags; > > - memcpy(&compat_event->pointer, > > - ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > > - hdr_len - IW_EV_COMPAT_LCP_LEN); > > + memcpy(compat_event->ptr_bytes, > > + ((char *)&compat_wrqu) + IW_EV_COMPAT_POINT_OFF, > > + ptr_len); > > if (extra_len) > > - memcpy(((char *) compat_event) + hdr_len, > > - extra, extra_len); > > + memcpy(&compat_event->ptr_bytes[ptr_len], > > + extra, extra_len); > > } else { > > /* extra_len must be zero, so no if (extra) needed */ > > - memcpy(&compat_event->pointer, wrqu, > > - hdr_len - IW_EV_COMPAT_LCP_LEN); > > + memcpy(compat_event->ptr_bytes, wrqu, ptr_len); > > } > > > > nlmsg_end(compskb, nlh); > > -- > > 2.25.1 > > ^ permalink raw reply [flat|nested] 18+ messages in thread
* Re: [PATCH] wext: use flex array destination for memcpy() 2022-09-26 15:09 ` [PATCH] wext: use flex array destination for memcpy() Hawkins Jiawei 2022-09-26 16:14 ` Eric Dumazet @ 2022-09-26 17:43 ` Kees Cook 1 sibling, 0 replies; 18+ messages in thread From: Kees Cook @ 2022-09-26 17:43 UTC (permalink / raw) To: Hawkins Jiawei Cc: syzbot+473754e5af963cf014cf, Johannes Berg, David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni, linux-kernel, linux-wireless, netdev, syzkaller-bugs, 18801353760 On Mon, Sep 26, 2022 at 11:09:06PM +0800, Hawkins Jiawei wrote: > Syzkaller reports refcount bug as follows: "buffer overflow false positive" instead of "refcount bug" > ------------[ cut here ]------------ > memcpy: detected field-spanning write (size 8) of single field > "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) > WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 > wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 > Modules linked in: > CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted > 6.0.0-rc6-next-20220921-syzkaller #0 > [...] > Call Trace: > <TASK> > ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 > wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 > wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] > wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] > wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 > sock_ioctl+0x285/0x640 net/socket.c:1220 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:870 [inline] > __se_sys_ioctl fs/ioctl.c:856 [inline] > __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > [...] > </TASK> > > Wireless events will be sent on the appropriate channels in > wireless_send_event(). Different wireless events may have different > payload structure and size, so kernel uses **len** and **cmd** field > in struct __compat_iw_event as wireless event common LCP part, uses > **pointer** as a label to mark the position of remaining different part. > > Yet the problem is that, **pointer** is a compat_caddr_t type, which may > be smaller than the relative structure at the same position. So during > wireless_send_event() tries to parse the wireless events payload, it may > trigger the memcpy() run-time destination buffer bounds checking when the > relative structure's data is copied to the position marked by **pointer**. > > This patch solves it by introducing flexible-array field **ptr_bytes**, > to mark the position of the wireless events remaining part next to > LCP part. What's more, this patch also adds **ptr_len** variable in > wireless_send_event() to improve its maintainability. > > Reported-and-tested-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com > Link: https://lore.kernel.org/all/00000000000070db2005e95a5984@google.com/ > Suggested-by: Kees Cook <keescook@chromium.org> > Signed-off-by: Hawkins Jiawei <yin31149@gmail.com> Thanks for spinning this and getting it tested! Reviewed-by: Kees Cook <keescook@chromium.org> -- Kees Cook ^ permalink raw reply [flat|nested] 18+ messages in thread
* [PATCH wireless-next v2] wext: use flex array destination for memcpy() 2022-09-23 16:05 [syzbot] WARNING in wireless_send_event syzbot ` (2 preceding siblings ...) 2022-09-26 15:09 ` [PATCH] wext: use flex array destination for memcpy() Hawkins Jiawei @ 2022-09-26 23:34 ` Hawkins Jiawei 3 siblings, 0 replies; 18+ messages in thread From: Hawkins Jiawei @ 2022-09-26 23:34 UTC (permalink / raw) To: syzbot+473754e5af963cf014cf, edumazet, Johannes Berg, David S. Miller, Jakub Kicinski, Paolo Abeni Cc: 18801353760, keescook, linux-kernel, linux-wireless, netdev, syzkaller-bugs, yin31149 Syzkaller reports buffer overflow false positive as follows: ------------[ cut here ]------------ memcpy: detected field-spanning write (size 8) of single field "&compat_event->pointer" at net/wireless/wext-core.c:623 (size 4) WARNING: CPU: 0 PID: 3607 at net/wireless/wext-core.c:623 wireless_send_event+0xab5/0xca0 net/wireless/wext-core.c:623 Modules linked in: CPU: 1 PID: 3607 Comm: syz-executor659 Not tainted 6.0.0-rc6-next-20220921-syzkaller #0 [...] Call Trace: <TASK> ioctl_standard_call+0x155/0x1f0 net/wireless/wext-core.c:1022 wireless_process_ioctl+0xc8/0x4c0 net/wireless/wext-core.c:955 wext_ioctl_dispatch net/wireless/wext-core.c:988 [inline] wext_ioctl_dispatch net/wireless/wext-core.c:976 [inline] wext_handle_ioctl+0x26b/0x280 net/wireless/wext-core.c:1049 sock_ioctl+0x285/0x640 net/socket.c:1220 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] </TASK> Wireless events will be sent on the appropriate channels in wireless_send_event(). Different wireless events may have different payload structure and size, so kernel uses **len** and **cmd** field in struct __compat_iw_event as wireless event common LCP part, uses **pointer** as a label to mark the position of remaining different part. Yet the problem is that, **pointer** is a compat_caddr_t type, which may be smaller than the relative structure at the same position. So during wireless_send_event() tries to parse the wireless events payload, it may trigger the memcpy() run-time destination buffer bounds checking when the relative structure's data is copied to the position marked by **pointer**. This patch solves it by introducing flexible-array field **ptr_bytes**, to mark the position of the wireless events remaining part next to LCP part. What's more, this patch also adds **ptr_len** variable in wireless_send_event() to improve its maintainability. Reported-and-tested-by: syzbot+473754e5af963cf014cf@syzkaller.appspotmail.com Link: https://lore.kernel.org/all/00000000000070db2005e95a5984@google.com/ Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Hawkins Jiawei <yin31149@gmail.com> --- v2: correct the typo error pointed out by Eric Dumazet and Kees Cook v1: https://lore.kernel.org/all/20220926150907.8551-1-yin31149@gmail.com/ include/linux/wireless.h | 10 +++++++++- net/wireless/wext-core.c | 17 ++++++++++------- 2 files changed, 19 insertions(+), 8 deletions(-) diff --git a/include/linux/wireless.h b/include/linux/wireless.h index 2d1b54556eff..e6e34d74dda0 100644 --- a/include/linux/wireless.h +++ b/include/linux/wireless.h @@ -26,7 +26,15 @@ struct compat_iw_point { struct __compat_iw_event { __u16 len; /* Real length of this stuff */ __u16 cmd; /* Wireless IOCTL */ - compat_caddr_t pointer; + + union { + compat_caddr_t pointer; + + /* we need ptr_bytes to make memcpy() run-time destination + * buffer bounds checking happy, nothing special + */ + DECLARE_FLEX_ARRAY(__u8, ptr_bytes); + }; }; #define IW_EV_COMPAT_LCP_LEN offsetof(struct __compat_iw_event, pointer) #define IW_EV_COMPAT_POINT_OFF offsetof(struct compat_iw_point, length) diff --git a/net/wireless/wext-core.c b/net/wireless/wext-core.c index 76a80a41615b..fe8765c4075d 100644 --- a/net/wireless/wext-core.c +++ b/net/wireless/wext-core.c @@ -468,6 +468,7 @@ void wireless_send_event(struct net_device * dev, struct __compat_iw_event *compat_event; struct compat_iw_point compat_wrqu; struct sk_buff *compskb; + int ptr_len; #endif /* @@ -582,6 +583,9 @@ void wireless_send_event(struct net_device * dev, nlmsg_end(skb, nlh); #ifdef CONFIG_COMPAT hdr_len = compat_event_type_size[descr->header_type]; + + /* ptr_len is remaining size in event header apart from LCP */ + ptr_len = hdr_len - IW_EV_COMPAT_LCP_LEN; event_len = hdr_len + extra_len; compskb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); @@ -612,16 +616,15 @@ void wireless_send_event(struct net_device * dev, if (descr->header_type == IW_HEADER_TYPE_POINT) { compat_wrqu.length = wrqu->data.length; compat_wrqu.flags = wrqu->data.flags; - memcpy(&compat_event->pointer, - ((char *) &compat_wrqu) + IW_EV_COMPAT_POINT_OFF, - hdr_len - IW_EV_COMPAT_LCP_LEN); + memcpy(compat_event->ptr_bytes, + ((char *)&compat_wrqu) + IW_EV_COMPAT_POINT_OFF, + ptr_len); if (extra_len) - memcpy(((char *) compat_event) + hdr_len, - extra, extra_len); + memcpy(&compat_event->ptr_bytes[ptr_len], + extra, extra_len); } else { /* extra_len must be zero, so no if (extra) needed */ - memcpy(&compat_event->pointer, wrqu, - hdr_len - IW_EV_COMPAT_LCP_LEN); + memcpy(compat_event->ptr_bytes, wrqu, ptr_len); } nlmsg_end(compskb, nlh); -- 2.25.1 ^ permalink raw reply related [flat|nested] 18+ messages in thread
end of thread, other threads:[~2022-09-26 23:35 UTC | newest] Thread overview: 18+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-09-23 16:05 [syzbot] WARNING in wireless_send_event syzbot 2022-09-24 7:10 ` [PATCH] Add linux-next specific files for 20220923 Hawkins Jiawei 2022-09-24 7:26 ` Kees Cook 2022-09-24 11:44 ` Hawkins Jiawei 2022-09-24 15:55 ` Hawkins Jiawei 2022-09-24 15:55 ` syzbot 2022-09-24 16:13 ` Hawkins Jiawei 2022-09-24 16:33 ` [syzbot] WARNING in wireless_send_event syzbot 2022-09-24 16:26 ` [PATCH] Add linux-next specific files for 20220923 Kees Cook 2022-09-25 6:25 ` Hawkins Jiawei 2022-09-24 7:32 ` [syzbot] WARNING in wireless_send_event syzbot 2022-09-26 11:59 ` Hawkins Jiawei 2022-09-26 12:24 ` syzbot 2022-09-26 15:09 ` [PATCH] wext: use flex array destination for memcpy() Hawkins Jiawei 2022-09-26 16:14 ` Eric Dumazet 2022-09-26 23:17 ` Hawkins Jiawei 2022-09-26 17:43 ` Kees Cook 2022-09-26 23:34 ` [PATCH wireless-next v2] " Hawkins Jiawei
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