Re: general protection fault in lockdep_invariant_state (2)

[Dmitry Vyukov]

On Mon, Nov 20, 2017 at 2:28 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
>>> > R13: 0000000000402260 R14: 00000000004022f0 R15: 0000000000000000
>>> > kasan: CONFIG_KASAN_INLINE enabled
>>> > kasan: GPF could be caused by NULL-ptr deref or user memory access
>>> > general protection fault: 0000 [#1] SMP KASAN
>>> > Dumping ftrace buffer:
>>> >    (ftrace buffer empty)
>>> > Modules linked in:
>>> > CPU: 3 PID: 2982 Comm: syzkaller521009 Not tainted 4.14.0-rc7-next-20171103+
>>> > #10
>>> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>> > task: ffff88003d6b25c0 task.stack: ffff88003abd0000
>>> > RIP: 0010:invalidate_xhlock kernel/locking/lockdep.c:4719 [inline]
>>> > RIP: 0010:lockdep_invariant_state+0xd6/0x120 kernel/locking/lockdep.c:4793
>>
>>
>> Does this help?
>>
>> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
>> index db933d063bfc..da2904418599 100644
>> --- a/kernel/locking/lockdep.c
>> +++ b/kernel/locking/lockdep.c
>> @@ -4793,7 +4793,8 @@ void lockdep_invariant_state(bool force)
>>          * Verify the former, enforce the latter.
>>          */
>>         WARN_ON_ONCE(!force && current->lockdep_depth);
>> -       invalidate_xhlock(&xhlock(current->xhlock_idx));
>> +       if (current->xhlocks)
>> +               invalidate_xhlock(&xhlock(current->xhlock_idx));
>>  }
>>
>>  static int cross_lock(struct lockdep_map *lock)
>
>
> Hi Peter,
>
> We are not able to test all fixes for all bugs, but we are rolling out
> a patch testing feature for syzbot:
>
> https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
>
> Please give it a try!


Peter, ping.
This still happens. Please either submit the fix if you already tested
it, or test using syzbot and submit.