* general protection fault in path_openat
@ 2020-02-01 4:48 syzbot
2020-02-01 5:34 ` Al Viro
2020-02-01 17:08 ` syzbot
0 siblings, 2 replies; 3+ messages in thread
From: syzbot @ 2020-02-01 4:48 UTC (permalink / raw)
To: linux-fsdevel, linux-kernel, syzkaller-bugs, viro
Hello,
syzbot found the following crash on:
HEAD commit: ccaaaf6f Merge tag 'mpx-for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=115bda4ee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=879390c6b09ccf66
dashboard link: https://syzkaller.appspot.com/bug?extid=190005201ced78a74ad6
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1674c776e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1565e101e00000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+190005201ced78a74ad6@syzkaller.appspotmail.com
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 3515 Comm: modprobe Not tainted 5.5.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:do_last fs/namei.c:3336 [inline]
RIP: 0010:path_openat+0x281/0x3460 fs/namei.c:3607
Code: ff df 48 c1 ea 03 80 3c 02 00 0f 85 76 29 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 5c 24 58 48 8d 7b 04 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 28
RSP: 0018:ffffc90003c37a40 EFLAGS: 00010247
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81c24369
RDX: 0000000000000000 RSI: ffffffff81c24376 RDI: 0000000000000004
RBP: ffffc90003c37b90 R08: ffff88809dca63c0 R09: ffffed1015416ca2
R10: ffffed1015416ca1 R11: ffff8880aa0b6508 R12: ffff8880aa0b64a0
R13: ffff88809dca63c0 R14: ffffc90003c37d98 R15: ffffc90003c37bd0
FS: 00007f70d677c700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000009a184000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
do_filp_open+0x192/0x260 fs/namei.c:3637
do_sys_openat2+0x5eb/0x7e0 fs/open.c:1149
do_sys_open+0xf2/0x180 fs/open.c:1165
ksys_open include/linux/syscalls.h:1386 [inline]
__do_sys_open fs/open.c:1171 [inline]
__se_sys_open fs/open.c:1169 [inline]
__x64_sys_open+0x7e/0xc0 fs/open.c:1169
do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f70d6094120
Code: 48 8b 15 1b 4d 2b 00 f7 d8 64 89 02 83 c8 ff c3 90 90 90 90 90 90 90 90 90 90 83 3d d5 a4 2b 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 5e 8c 01 00 48 89 04 24
RSP: 002b:00007ffdbe2762c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 0000558ff35f3240 RCX: 00007f70d6094120
RDX: 00007ffdbe2764fc RSI: 0000000000080000 RDI: 00007ffdbe2764e0
RBP: 00007f70d6564300 R08: 0000000000000000 R09: 0000558ff35f3219
R10: 0000000000000000 R11: 0000000000000246 R12: 0000558ff35eb210
R13: 0000558ff35f3210 R14: 0000558ff35eb210 R15: 00007ffdbe2764e0
Modules linked in:
---[ end trace bdc3fba9ce9969a3 ]---
RIP: 0010:do_last fs/namei.c:3336 [inline]
RIP: 0010:path_openat+0x281/0x3460 fs/namei.c:3607
Code: ff df 48 c1 ea 03 80 3c 02 00 0f 85 76 29 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 5c 24 58 48 8d 7b 04 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 28
RSP: 0018:ffffc90003c37a40 EFLAGS: 00010247
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81c24369
RDX: 0000000000000000 RSI: ffffffff81c24376 RDI: 0000000000000004
RBP: ffffc90003c37b90 R08: ffff88809dca63c0 R09: ffffed1015416ca2
R10: ffffed1015416ca1 R11: ffff8880aa0b6508 R12: ffff8880aa0b64a0
R13: ffff88809dca63c0 R14: ffffc90003c37d98 R15: ffffc90003c37bd0
FS: 00007f70d677c700(0000) GS:ffff8880ae900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdd12577518 CR3: 000000009a184000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: general protection fault in path_openat
2020-02-01 4:48 general protection fault in path_openat syzbot
@ 2020-02-01 5:34 ` Al Viro
2020-02-01 17:08 ` syzbot
1 sibling, 0 replies; 3+ messages in thread
From: Al Viro @ 2020-02-01 5:34 UTC (permalink / raw)
To: syzbot; +Cc: linux-fsdevel, linux-kernel, syzkaller-bugs
On Fri, Jan 31, 2020 at 08:48:11PM -0800, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: ccaaaf6f Merge tag 'mpx-for-linus' of git://git.kernel.org..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=115bda4ee00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=879390c6b09ccf66
> dashboard link: https://syzkaller.appspot.com/bug?extid=190005201ced78a74ad6
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1674c776e00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1565e101e00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+190005201ced78a74ad6@syzkaller.appspotmail.com
Already reported; see if the following fixes that:
diff --git a/fs/namei.c b/fs/namei.c
index 4167109297e0..db6565c99825 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3333,8 +3333,8 @@ static int do_last(struct nameidata *nd,
struct file *file, const struct open_flags *op)
{
struct dentry *dir = nd->path.dentry;
- kuid_t dir_uid = dir->d_inode->i_uid;
- umode_t dir_mode = dir->d_inode->i_mode;
+ kuid_t dir_uid = nd->inode->i_uid;
+ umode_t dir_mode = nd->inode->i_mode;
int open_flag = op->open_flag;
bool will_truncate = (open_flag & O_TRUNC) != 0;
bool got_write = false;
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: general protection fault in path_openat
2020-02-01 4:48 general protection fault in path_openat syzbot
2020-02-01 5:34 ` Al Viro
@ 2020-02-01 17:08 ` syzbot
1 sibling, 0 replies; 3+ messages in thread
From: syzbot @ 2020-02-01 17:08 UTC (permalink / raw)
To: linux-fsdevel, linux-kernel, syzkaller-bugs, viro
syzbot has bisected this bug to:
commit d0cb50185ae942b03c4327be322055d622dc79f6
Author: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun Jan 26 14:29:34 2020 +0000
do_last(): fetch directory ->i_mode and ->i_uid before it's too late
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=16a8d8b5e00000
start commit: ccaaaf6f Merge tag 'mpx-for-linus' of git://git.kernel.org..
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=15a8d8b5e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=11a8d8b5e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=879390c6b09ccf66
dashboard link: https://syzkaller.appspot.com/bug?extid=190005201ced78a74ad6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1674c776e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1565e101e00000
Reported-by: syzbot+190005201ced78a74ad6@syzkaller.appspotmail.com
Fixes: d0cb50185ae9 ("do_last(): fetch directory ->i_mode and ->i_uid before it's too late")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-02-01 4:48 general protection fault in path_openat syzbot
2020-02-01 5:34 ` Al Viro
2020-02-01 17:08 ` syzbot
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