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

From: Jens Axboe
Date: Tue Apr 27 2021 - 09:38:00 EST

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.

Jens Axboe