Re: [PATCH 5.13] io_uring: Check current->io_uring in io_uring_cancel_sqpoll

[Jens Axboe]

On 4/27/21 11:00 AM, Pavel Begunkov wrote:
> On 4/27/21 2:37 PM, Jens Axboe wrote:
>> On 4/27/21 6:51 AM, Palash Oswal wrote:
>>> syzkaller identified KASAN: null-ptr-deref Write in
>>> io_uring_cancel_sqpoll on v5.12
>>>
>>> io_uring_cancel_sqpoll is called by io_sq_thread before calling
>>> io_uring_alloc_task_context. This leads to current->io_uring being
>>> NULL. io_uring_cancel_sqpoll should not have to deal with threads
>>> where current->io_uring is NULL.
>>>
>>> In order to cast a wider safety net, perform input sanitisation
>>> directly in io_uring_cancel_sqpoll and return for NULL value of
>>> current->io_uring.
>>
>> Thanks applied - I augmented the commit message a bit.
> 
> btw, does it fixes the replied before syz report? Should 
> syz fix or tag it if so.
> Reported-by: syzbot+be51ca5a4d97f017cd50@xxxxxxxxxxxxxxxxxxxxxxxxx

That tag was already there.

-- 
Jens Axboe