Hello,
syzbot hit the following crash on upstream commit
38c23685b273cfb4ccf31a199feccce3bdcb5d83 (Fri Apr 6 04:29:35 2018 +0000)
Merge tag 'armsoc-drivers' of
git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=31e8daa8b3fc129e75f2
So far this crash happened 9 times on upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6407930337296384
syzkaller reproducer:
https://syzkaller.appspot.com/x/repro.syz?id=4942413340606464
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=4764483918495744
Kernel config:
https://syzkaller.appspot.com/x/.config?id=-5813481738265533882
compiler: gcc (GCC) 8.0.1 20180301 (experimental)
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: [email protected]
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.
================================================
WARNING: lock held when returning to user space!
4.16.0+ #3 Not tainted
------------------------------------------------
syzkaller433111/4462 is leaving the kernel with locks still held!
1 lock held by syzkaller433111/4462:
#0: 0000000003a06fae (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x1ec0
drivers/block/loop.c:1363
---
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On 4/6/18 7:02 AM, syzbot wrote:
> Hello,
>
> syzbot hit the following crash on upstream commit
> 38c23685b273cfb4ccf31a199feccce3bdcb5d83 (Fri Apr 6 04:29:35 2018 +0000)
> Merge tag 'armsoc-drivers' of
> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=31e8daa8b3fc129e75f2
>
> So far this crash happened 9 times on upstream.
> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6407930337296384
> syzkaller reproducer:
> https://syzkaller.appspot.com/x/repro.syz?id=4942413340606464
> Raw console output:
> https://syzkaller.appspot.com/x/log.txt?id=4764483918495744
> Kernel config:
> https://syzkaller.appspot.com/x/.config?id=-5813481738265533882
> compiler: gcc (GCC) 8.0.1 20180301 (experimental)
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: [email protected]
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.
>
>
> ================================================
> WARNING: lock held when returning to user space!
> 4.16.0+ #3 Not tainted
> ------------------------------------------------
> syzkaller433111/4462 is leaving the kernel with locks still held!
> 1 lock held by syzkaller433111/4462:
> #0: 0000000003a06fae (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x1ec0
> drivers/block/loop.c:1363
Is this a new regression? Omar did just fiddle with the locking a bit,
seems suspicious.
--
Jens Axboe
On Fri, Apr 6, 2018 at 4:27 PM, Jens Axboe <[email protected]> wrote:
> On 4/6/18 7:02 AM, syzbot wrote:
>> Hello,
>>
>> syzbot hit the following crash on upstream commit
>> 38c23685b273cfb4ccf31a199feccce3bdcb5d83 (Fri Apr 6 04:29:35 2018 +0000)
>> Merge tag 'armsoc-drivers' of
>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>> syzbot dashboard link:
>> https://syzkaller.appspot.com/bug?extid=31e8daa8b3fc129e75f2
>>
>> So far this crash happened 9 times on upstream.
>> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6407930337296384
>> syzkaller reproducer:
>> https://syzkaller.appspot.com/x/repro.syz?id=4942413340606464
>> Raw console output:
>> https://syzkaller.appspot.com/x/log.txt?id=4764483918495744
>> Kernel config:
>> https://syzkaller.appspot.com/x/.config?id=-5813481738265533882
>> compiler: gcc (GCC) 8.0.1 20180301 (experimental)
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: [email protected]
>> It will help syzbot understand when the bug is fixed. See footer for
>> details.
>> If you forward the report, please keep this part and the footer.
>>
>>
>> ================================================
>> WARNING: lock held when returning to user space!
>> 4.16.0+ #3 Not tainted
>> ------------------------------------------------
>> syzkaller433111/4462 is leaving the kernel with locks still held!
>> 1 lock held by syzkaller433111/4462:
>> #0: 0000000003a06fae (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x1ec0
>> drivers/block/loop.c:1363
>
> Is this a new regression? Omar did just fiddle with the locking a bit,
> seems suspicious.
Looking at:
https://syzkaller.appspot.com/bug?extid=31e8daa8b3fc129e75f2
It first happened 4 hours ago and 9 times since then, so probably a
just introduced regression.
> --
> Jens Axboe
>
> --
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On 4/6/18 8:57 AM, Dmitry Vyukov wrote:
> On Fri, Apr 6, 2018 at 4:27 PM, Jens Axboe <[email protected]> wrote:
>> On 4/6/18 7:02 AM, syzbot wrote:
>>> Hello,
>>>
>>> syzbot hit the following crash on upstream commit
>>> 38c23685b273cfb4ccf31a199feccce3bdcb5d83 (Fri Apr 6 04:29:35 2018 +0000)
>>> Merge tag 'armsoc-drivers' of
>>> git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
>>> syzbot dashboard link:
>>> https://syzkaller.appspot.com/bug?extid=31e8daa8b3fc129e75f2
>>>
>>> So far this crash happened 9 times on upstream.
>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6407930337296384
>>> syzkaller reproducer:
>>> https://syzkaller.appspot.com/x/repro.syz?id=4942413340606464
>>> Raw console output:
>>> https://syzkaller.appspot.com/x/log.txt?id=4764483918495744
>>> Kernel config:
>>> https://syzkaller.appspot.com/x/.config?id=-5813481738265533882
>>> compiler: gcc (GCC) 8.0.1 20180301 (experimental)
>>>
>>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>>> Reported-by: [email protected]
>>> It will help syzbot understand when the bug is fixed. See footer for
>>> details.
>>> If you forward the report, please keep this part and the footer.
>>>
>>>
>>> ================================================
>>> WARNING: lock held when returning to user space!
>>> 4.16.0+ #3 Not tainted
>>> ------------------------------------------------
>>> syzkaller433111/4462 is leaving the kernel with locks still held!
>>> 1 lock held by syzkaller433111/4462:
>>> #0: 0000000003a06fae (&lo->lo_ctl_mutex/1){+.+.}, at: lo_ioctl+0x8d/0x1ec0
>>> drivers/block/loop.c:1363
>>
>> Is this a new regression? Omar did just fiddle with the locking a bit,
>> seems suspicious.
>
> Looking at:
> https://syzkaller.appspot.com/bug?extid=31e8daa8b3fc129e75f2
> It first happened 4 hours ago and 9 times since then, so probably a
> just introduced regression.
After writing that, I saw the discussion in another
thread ("INFO: task hung in lo_ioctl"), so I think we can definitely say
that it's a recently introduced regression in loop due to the killable
lock changes.
--
Jens Axboe
The patch was sent to linux.git as commit bdac616db9bbadb9.
#syz fix: loop: fix LOOP_GET_STATUS lock imbalance