Re: [PATCH 1/1] io_uring/sqpoll: fix sqpoll error handling races

[Jens Axboe <axboe@kernel.dk>]

On 12/26/24 9:49 AM, Pavel Begunkov wrote:
> BUG: KASAN: slab-use-after-free in __lock_acquire+0x370b/0x4a10 kernel/locking/lockdep.c:5089
> Call Trace:
> <TASK>
> ...
> _raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
> class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]
> try_to_wake_up+0xb5/0x23c0 kernel/sched/core.c:4205
> io_sq_thread_park+0xac/0xe0 io_uring/sqpoll.c:55
> io_sq_thread_finish+0x6b/0x310 io_uring/sqpoll.c:96
> io_sq_offload_create+0x162/0x11d0 io_uring/sqpoll.c:497
> io_uring_create io_uring/io_uring.c:3724 [inline]
> io_uring_setup+0x1728/0x3230 io_uring/io_uring.c:3806
> ...
> 
> Kun Hu reports that the SQPOLL creating error path has UAF, which
> happens if io_uring_alloc_task_context() fails and then io_sq_thread()
> manages to run and complete before the rest of error handling code,
> which means io_sq_thread_finish() is looking at already killed task.

Might be worth mentioning that this is only really a fault injection
thing. But ouside of that, looks fine to me - thanks!

-- 
Jens Axboe