Re: KASAN: use-after-free Read in percpu_ref_switch_to_atomic_rcu

Jens Axboe
2020-03-04T14:40:07Z

On 3/4/20 12:59 AM, Dmitry Vyukov wrote:
> On Fri, Feb 7, 2020 at 9:14 AM syzbot
> <syzbot+e017e49c39ab484ac87a@syzkaller.appspotmail.com> wrote:
>>
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit: 4c7d00cc Merge tag 'pwm/for-5.6-rc1' of git://git.kernel.o..
>> git tree: upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=12fec785e00000
>> kernel config: https://syzkaller.appspot.com/x/.config?x=e162021ddededa72
>> dashboard link: https://syzkaller.appspot.com/bug?extid=e017e49c39ab484ac87a
>> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
>>
>> Unfortunately, I don't have any reproducer for this crash yet.
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+e017e49c39ab484ac87a@syzkaller.appspotmail.com
>
> +io_uring maintainers
>
> Here is a repro:
> https://gist.githubusercontent.com/dvyukov/6b340beab6483a036f4186e7378882ce/raw/cd1922185516453c201df8eded1d4b006a6d6a3a/gistfile1.txt

I've queued up a fix for this:

https://git.kernel.dk/cgit/linux-block/commit/?h=io_uring-5.6&id=9875fe3dc4b8cff1f1b440fb925054a5124403c3

--
Jens Axboe