* KMSAN: uninit-value in audit_log_vformat (2)
@ 2020-04-20 5:35 syzbot
2020-04-20 16:29 ` Paul Moore
0 siblings, 1 reply; 4+ messages in thread
From: syzbot @ 2020-04-20 5:35 UTC (permalink / raw)
To: eparis, glider, linux-audit, linux-kernel, paul, syzkaller-bugs
Hello,
syzbot found the following crash on:
HEAD commit: 5356842d [EXPERIMENTAL] kmsan: eagerly allocate shadow at ..
git tree: https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=12f06720100000
kernel config: https://syzkaller.appspot.com/x/.config?x=a5915107b3106aaa
dashboard link: https://syzkaller.appspot.com/bug?extid=49e69b4d71a420ceda3e
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133b5dabe00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=143e1610100000
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com
=====================================================
BUG: KMSAN: uninit-value in string_nocheck lib/vsprintf.c:608 [inline]
BUG: KMSAN: uninit-value in string+0x522/0x690 lib/vsprintf.c:689
CPU: 1 PID: 8854 Comm: syz-executor694 Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1c9/0x220 lib/dump_stack.c:118
kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
__msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
string_nocheck lib/vsprintf.c:608 [inline]
string+0x522/0x690 lib/vsprintf.c:689
vsnprintf+0x207d/0x31b0 lib/vsprintf.c:2574
audit_log_vformat+0x583/0xcd0 kernel/audit.c:1858
audit_log_format+0x220/0x260 kernel/audit.c:1892
audit_receive_msg kernel/audit.c:1344 [inline]
audit_receive+0x18a4/0x6d50 kernel/audit.c:1515
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1329
netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg net/socket.c:672 [inline]
____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345
___sys_sendmsg net/socket.c:2399 [inline]
__sys_sendmsg+0x451/0x5f0 net/socket.c:2432
__compat_sys_sendmsg net/compat.c:642 [inline]
__do_compat_sys_sendmsg net/compat.c:649 [inline]
__se_compat_sys_sendmsg net/compat.c:646 [inline]
__ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646
do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7fa0d99
Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000ffb27c7c EFLAGS: 00000246 ORIG_RAX: 0000000000000172
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200002c0
RDX: 0000000000000000 RSI: 00000000080ea078 RDI: 00000000ffb27cd0
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Uninit was created at:
kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82
slab_alloc_node mm/slub.c:2801 [inline]
__kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4420
__kmalloc_reserve net/core/skbuff.c:142 [inline]
__alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210
alloc_skb include/linux/skbuff.h:1081 [inline]
netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline]
netlink_sendmsg+0x7d3/0x14d0 net/netlink/af_netlink.c:1893
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg net/socket.c:672 [inline]
____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345
___sys_sendmsg net/socket.c:2399 [inline]
__sys_sendmsg+0x451/0x5f0 net/socket.c:2432
__compat_sys_sendmsg net/compat.c:642 [inline]
__do_compat_sys_sendmsg net/compat.c:649 [inline]
__se_compat_sys_sendmsg net/compat.c:646 [inline]
__ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646
do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
=====================================================
---
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
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: KMSAN: uninit-value in audit_log_vformat (2)
2020-04-20 5:35 KMSAN: uninit-value in audit_log_vformat (2) syzbot
@ 2020-04-20 16:29 ` Paul Moore
2020-04-20 18:12 ` Dmitry Vyukov
0 siblings, 1 reply; 4+ messages in thread
From: Paul Moore @ 2020-04-20 16:29 UTC (permalink / raw)
To: syzbot; +Cc: syzkaller-bugs, linux-audit, glider, linux-kernel
On Mon, Apr 20, 2020 at 1:35 AM syzbot
<syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 5356842d [EXPERIMENTAL] kmsan: eagerly allocate shadow at ..
> git tree: https://github.com/google/kmsan.git master
> console output: https://syzkaller.appspot.com/x/log.txt?x=12f06720100000
> kernel config: https://syzkaller.appspot.com/x/.config?x=a5915107b3106aaa
> dashboard link: https://syzkaller.appspot.com/bug?extid=49e69b4d71a420ceda3e
> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> userspace arch: i386
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133b5dabe00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=143e1610100000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com
>
> =====================================================
> BUG: KMSAN: uninit-value in string_nocheck lib/vsprintf.c:608 [inline]
> BUG: KMSAN: uninit-value in string+0x522/0x690 lib/vsprintf.c:689
> CPU: 1 PID: 8854 Comm: syz-executor694 Not tainted 5.6.0-rc7-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x1c9/0x220 lib/dump_stack.c:118
> kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
> __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
> string_nocheck lib/vsprintf.c:608 [inline]
> string+0x522/0x690 lib/vsprintf.c:689
> vsnprintf+0x207d/0x31b0 lib/vsprintf.c:2574
Are there any ongoing problems with [vsn]printf() in the kernel at the
moment with syzbot?
I ask because on first look I'm not seeing any obvious problems in the
audit portion of this code path.
> audit_log_vformat+0x583/0xcd0 kernel/audit.c:1858
> audit_log_format+0x220/0x260 kernel/audit.c:1892
> audit_receive_msg kernel/audit.c:1344 [inline]
> audit_receive+0x18a4/0x6d50 kernel/audit.c:1515
> netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
> netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1329
> netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1918
> sock_sendmsg_nosec net/socket.c:652 [inline]
> sock_sendmsg net/socket.c:672 [inline]
> ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345
> ___sys_sendmsg net/socket.c:2399 [inline]
> __sys_sendmsg+0x451/0x5f0 net/socket.c:2432
> __compat_sys_sendmsg net/compat.c:642 [inline]
> __do_compat_sys_sendmsg net/compat.c:649 [inline]
> __se_compat_sys_sendmsg net/compat.c:646 [inline]
> __ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646
> do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
> do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
> entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
> RIP: 0023:0xf7fa0d99
> Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
> RSP: 002b:00000000ffb27c7c EFLAGS: 00000246 ORIG_RAX: 0000000000000172
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200002c0
> RDX: 0000000000000000 RSI: 00000000080ea078 RDI: 00000000ffb27cd0
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
>
> Uninit was created at:
> kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
> kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
> kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82
> slab_alloc_node mm/slub.c:2801 [inline]
> __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4420
> __kmalloc_reserve net/core/skbuff.c:142 [inline]
> __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210
> alloc_skb include/linux/skbuff.h:1081 [inline]
> netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline]
> netlink_sendmsg+0x7d3/0x14d0 net/netlink/af_netlink.c:1893
> sock_sendmsg_nosec net/socket.c:652 [inline]
> sock_sendmsg net/socket.c:672 [inline]
> ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345
> ___sys_sendmsg net/socket.c:2399 [inline]
> __sys_sendmsg+0x451/0x5f0 net/socket.c:2432
> __compat_sys_sendmsg net/compat.c:642 [inline]
> __do_compat_sys_sendmsg net/compat.c:649 [inline]
> __se_compat_sys_sendmsg net/compat.c:646 [inline]
> __ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646
> do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
> do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
> entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
> =====================================================
--
paul moore
www.paul-moore.com
--
Linux-audit mailing list
Linux-audit@redhat.com
https://www.redhat.com/mailman/listinfo/linux-audit
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: KMSAN: uninit-value in audit_log_vformat (2)
2020-04-20 16:29 ` Paul Moore
@ 2020-04-20 18:12 ` Dmitry Vyukov
2020-04-20 20:26 ` Paul Moore
0 siblings, 1 reply; 4+ messages in thread
From: Dmitry Vyukov @ 2020-04-20 18:12 UTC (permalink / raw)
To: Paul Moore; +Cc: syzbot, syzkaller-bugs, LKML, linux-audit, Alexander Potapenko
On Mon, Apr 20, 2020 at 6:29 PM Paul Moore <paul@paul-moore.com> wrote:
>
> On Mon, Apr 20, 2020 at 1:35 AM syzbot
> <syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com> wrote:
> >
> > Hello,
> >
> > syzbot found the following crash on:
> >
> > HEAD commit: 5356842d [EXPERIMENTAL] kmsan: eagerly allocate shadow at ..
> > git tree: https://github.com/google/kmsan.git master
> > console output: https://syzkaller.appspot.com/x/log.txt?x=12f06720100000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=a5915107b3106aaa
> > dashboard link: https://syzkaller.appspot.com/bug?extid=49e69b4d71a420ceda3e
> > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> > userspace arch: i386
> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133b5dabe00000
> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=143e1610100000
> >
> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > Reported-by: syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com
> >
> > =====================================================
> > BUG: KMSAN: uninit-value in string_nocheck lib/vsprintf.c:608 [inline]
> > BUG: KMSAN: uninit-value in string+0x522/0x690 lib/vsprintf.c:689
> > CPU: 1 PID: 8854 Comm: syz-executor694 Not tainted 5.6.0-rc7-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Call Trace:
> > __dump_stack lib/dump_stack.c:77 [inline]
> > dump_stack+0x1c9/0x220 lib/dump_stack.c:118
> > kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
> > __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
> > string_nocheck lib/vsprintf.c:608 [inline]
> > string+0x522/0x690 lib/vsprintf.c:689
> > vsnprintf+0x207d/0x31b0 lib/vsprintf.c:2574
>
> Are there any ongoing problems with [vsn]printf() in the kernel at the
> moment with syzbot?
>
> I ask because on first look I'm not seeing any obvious problems in the
> audit portion of this code path.
None I am aware of. Alex?
Can it be related to data_len==0? I don't see any obvious checks for
this. And in that case will 0-terminate out-of-bounds (at offset -1?)
and print potentially uninit data. But I looked at the code only very
briefly so potentially I am totally wrong.
> > audit_log_vformat+0x583/0xcd0 kernel/audit.c:1858
> > audit_log_format+0x220/0x260 kernel/audit.c:1892
> > audit_receive_msg kernel/audit.c:1344 [inline]
> > audit_receive+0x18a4/0x6d50 kernel/audit.c:1515
> > netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
> > netlink_unicast+0xf9e/0x1100 net/netlink/af_netlink.c:1329
> > netlink_sendmsg+0x1246/0x14d0 net/netlink/af_netlink.c:1918
> > sock_sendmsg_nosec net/socket.c:652 [inline]
> > sock_sendmsg net/socket.c:672 [inline]
> > ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345
> > ___sys_sendmsg net/socket.c:2399 [inline]
> > __sys_sendmsg+0x451/0x5f0 net/socket.c:2432
> > __compat_sys_sendmsg net/compat.c:642 [inline]
> > __do_compat_sys_sendmsg net/compat.c:649 [inline]
> > __se_compat_sys_sendmsg net/compat.c:646 [inline]
> > __ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646
> > do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
> > do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
> > entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
> > RIP: 0023:0xf7fa0d99
> > Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
> > RSP: 002b:00000000ffb27c7c EFLAGS: 00000246 ORIG_RAX: 0000000000000172
> > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000200002c0
> > RDX: 0000000000000000 RSI: 00000000080ea078 RDI: 00000000ffb27cd0
> > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> >
> > Uninit was created at:
> > kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
> > kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
> > kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82
> > slab_alloc_node mm/slub.c:2801 [inline]
> > __kmalloc_node_track_caller+0xb40/0x1200 mm/slub.c:4420
> > __kmalloc_reserve net/core/skbuff.c:142 [inline]
> > __alloc_skb+0x2fd/0xac0 net/core/skbuff.c:210
> > alloc_skb include/linux/skbuff.h:1081 [inline]
> > netlink_alloc_large_skb net/netlink/af_netlink.c:1175 [inline]
> > netlink_sendmsg+0x7d3/0x14d0 net/netlink/af_netlink.c:1893
> > sock_sendmsg_nosec net/socket.c:652 [inline]
> > sock_sendmsg net/socket.c:672 [inline]
> > ____sys_sendmsg+0x12b6/0x1350 net/socket.c:2345
> > ___sys_sendmsg net/socket.c:2399 [inline]
> > __sys_sendmsg+0x451/0x5f0 net/socket.c:2432
> > __compat_sys_sendmsg net/compat.c:642 [inline]
> > __do_compat_sys_sendmsg net/compat.c:649 [inline]
> > __se_compat_sys_sendmsg net/compat.c:646 [inline]
> > __ia32_compat_sys_sendmsg+0xed/0x130 net/compat.c:646
> > do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
> > do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
> > entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
> > =====================================================
>
> --
> paul moore
> www.paul-moore.com
>
> --
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: KMSAN: uninit-value in audit_log_vformat (2)
2020-04-20 18:12 ` Dmitry Vyukov
@ 2020-04-20 20:26 ` Paul Moore
0 siblings, 0 replies; 4+ messages in thread
From: Paul Moore @ 2020-04-20 20:26 UTC (permalink / raw)
To: Dmitry Vyukov
Cc: syzbot, syzkaller-bugs, LKML, linux-audit, Alexander Potapenko
On Mon, Apr 20, 2020 at 2:12 PM Dmitry Vyukov <dvyukov@google.com> wrote:
> On Mon, Apr 20, 2020 at 6:29 PM Paul Moore <paul@paul-moore.com> wrote:
> > On Mon, Apr 20, 2020 at 1:35 AM syzbot
> > <syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com> wrote:
> > >
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit: 5356842d [EXPERIMENTAL] kmsan: eagerly allocate shadow at ..
> > > git tree: https://github.com/google/kmsan.git master
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=12f06720100000
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=a5915107b3106aaa
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=49e69b4d71a420ceda3e
> > > compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
> > > userspace arch: i386
> > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133b5dabe00000
> > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=143e1610100000
> > >
> > > IMPORTANT: if you fix the bug, please add the following tag to the commit:
> > > Reported-by: syzbot+49e69b4d71a420ceda3e@syzkaller.appspotmail.com
> > >
> > > =====================================================
> > > BUG: KMSAN: uninit-value in string_nocheck lib/vsprintf.c:608 [inline]
> > > BUG: KMSAN: uninit-value in string+0x522/0x690 lib/vsprintf.c:689
> > > CPU: 1 PID: 8854 Comm: syz-executor694 Not tainted 5.6.0-rc7-syzkaller #0
> > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > > Call Trace:
> > > __dump_stack lib/dump_stack.c:77 [inline]
> > > dump_stack+0x1c9/0x220 lib/dump_stack.c:118
> > > kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
> > > __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
> > > string_nocheck lib/vsprintf.c:608 [inline]
> > > string+0x522/0x690 lib/vsprintf.c:689
> > > vsnprintf+0x207d/0x31b0 lib/vsprintf.c:2574
> >
> > Are there any ongoing problems with [vsn]printf() in the kernel at the
> > moment with syzbot?
> >
> > I ask because on first look I'm not seeing any obvious problems in the
> > audit portion of this code path.
>
> None I am aware of. Alex?
> Can it be related to data_len==0? I don't see any obvious checks for
> this. And in that case will 0-terminate out-of-bounds (at offset -1?)
> and print potentially uninit data. But I looked at the code only very
> briefly so potentially I am totally wrong.
Bingo, that's likely it. Thanks.
I was in the process of fixing another audit bug when I looked at this
and got fixated on the varg stuff, not the variables themselves. I'll
have a patch out later today.
--
paul moore
www.paul-moore.com
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2020-04-20 5:35 KMSAN: uninit-value in audit_log_vformat (2) syzbot
2020-04-20 16:29 ` Paul Moore
2020-04-20 18:12 ` Dmitry Vyukov
2020-04-20 20:26 ` Paul Moore
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