linux-kernel - Re: general protection fault in lockdep_invariant

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Date:   Thu, 7 Dec 2017 09:07:49 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     syzbot 
        <bot+2e39c7a45268c036c9e90433a48c9dd550276dc6@...kaller.appspotmail.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, syzkaller-bugs@...glegroups.com
Subject: Re: general protection fault in lockdep_invariant_state (2)

On Wed, Dec 6, 2017 at 5:31 PM, Dmitry Vyukov <dvyukov@...gle.com> 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.
>>>
>>>
>>> Peter, do you want me to mail your patch?
>>
>> Urgh, sorry, got stuck doing KAISER muck. I'll go write up a proper
>> patch.
>
> Thanks!



I see the patch is landed in tip. Please also follow this part:

> 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.

This will greatly help to keep the process running.