Re: WARNING in do_debug

[Dmitry Vyukov]

On Tue, Dec 26, 2017 at 1:55 AM, Wanpeng Li <kernellwp@xxxxxxxxx> wrote:
> 2017-12-26 8:22 GMT+08:00 syzbot
> <syzbot+adbefe6736a5b37af36f19ebfa8764fcdd9ddaed@xxxxxxxxxxxxxxxxxxxxxxxxx>:
>> syzkaller has found reproducer for the following crash on
>> 464e1d5f23cca236b930ef068c328a64cab78fb1
>> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
>> compiler: gcc (GCC) 7.1.1 20170620
>> .config is attached
>> Raw console output is attached.
>> C reproducer is attached
>> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
>> for information about syzkaller reproducers
>>
>
> https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?h=queue&id=ed3b37ac63a060bdc184d126c0655c1af8b6de62
>
> There is a fix in kvm/queue.

Hi Wanpeng,

syzbot does not know about the fix and still thinks that this bug is
open. Please tell it about the fix:


> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title
> Note: all commands must start from beginning of the line.




>> WARNING: CPU: 0 PID: 3356 at arch/x86/kernel/traps.c:801
>> cond_local_irq_disable arch/x86/kernel/traps.c:86 [inline]
>> WARNING: CPU: 0 PID: 3356 at arch/x86/kernel/traps.c:801
>> do_debug+0x4d8/0x6e0 arch/x86/kernel/traps.c:815
>> Kernel panic - not syncing: panic_on_warn set ...
>>
>> CPU: 0 PID: 3356 Comm: syzkaller834441 Not tainted 4.15.0-rc5+ #237
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Call Trace:
>>  <#DB>
>>  __dump_stack lib/dump_stack.c:17 [inline]
>>  dump_stack+0x194/0x257 lib/dump_stack.c:53
>>  panic+0x1e4/0x41c kernel/panic.c:183
>>  __warn+0x1dc/0x200 kernel/panic.c:547
>>  report_bug+0x211/0x2d0 lib/bug.c:184
>>  fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
>>  fixup_bug arch/x86/kernel/traps.c:247 [inline]
>>  do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
>>  do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
>>  invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:1061
>> RIP: 0010:cond_local_irq_disable arch/x86/kernel/traps.c:86 [inline]
>> RIP: 0010:do_debug+0x4d8/0x6e0 arch/x86/kernel/traps.c:815
>> RSP: 0018:fffffe800000ee98 EFLAGS: 00010246
>> RAX: dffffc0000000000 RBX: fffffe800000ef58 RCX: 0000000000000000
>> RDX: 1fffffd000001dfc RSI: 0000000000000001 RDI: ffffffff85ec81f8
>> RBP: fffffe800000ef48 R08: fffffe800000efe8 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000000 R12: 000000000000e003
>> R13: ffff8801c2340040 R14: 1fffffd000001dd8 R15: 0000000000004000
>>  debug+0x34/0x60 arch/x86/entry/entry_64.S:1214
>> RIP: 0010:__put_user_8+0x1f/0x25 arch/x86/lib/putuser.S:83
>> RSP: 0018:ffff8801c9f8ff28 EFLAGS: 00000293
>> RAX: 000000005a4195b6 RBX: 00007fffffffeff9 RCX: 0000000020000000
>> RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000282
>> RBP: ffff8801c9f8ff48 R08: 0000000000000000 R09: 1ffff100393f1fc2
>> R10: ffff8801c9f8fdd8 R11: 0000000000000000 R12: 000000005a4195b6
>> R13: 0000000020000000 R14: 00007f2c937f99c0 R15: 0000000000000001
>>  </#DB>
>>  entry_SYSCALL_64_fastpath+0x1f/0x96
>> RIP: 0033:0x44aef9
>> RSP: 002b:00007f2c937f8ce8 EFLAGS: 00000206 ORIG_RAX: 00000000000000c9
>> RAX: ffffffffffffffda RBX: 00000000006dcc24 RCX: 000000000044aef9
>> RDX: 000000000044aef9 RSI: 000000000044aef9 RDI: 0000000020000000
>> RBP: 00000000006dcc20 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
>> R13: 00007ffe9191073f R14: 00007f2c937f99c0 R15: 0000000000000001
>>
>> Dumping ftrace buffer:
>>    (ftrace buffer empty)
>> Kernel Offset: disabled
>> Rebooting in 86400 seconds..
>>