__io_req_task_submit() run by task_work can set mm and files, but io_sq_thread() in some cases, and because __io_sq_thread_acquire_mm() and __io_sq_thread_acquire_files() do a simple current->mm/files check it may end up submitting IO with mm/files of another task.

We also need to drop it after in the end to drop potentially grabbed references to them.

Cc: stable@vger.kernel.org # 5.9+ Signed-off-by: Pavel Begunkov asml.silence@gmail.com --- fs/io_uring.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/fs/io_uring.c b/fs/io_uring.c index 2f305c097bd5..7af74c1ec909 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7056,6 +7056,7 @@ static int io_sq_thread(void *data)

if (sqt_spin || !time_after(jiffies, timeout)) { io_run_task_work(); + io_sq_thread_drop_mm_files(); cond_resched(); if (sqt_spin) timeout = jiffies + sqd->sq_thread_idle; @@ -7093,6 +7094,7 @@ static int io_sq_thread(void *data) }

io_run_task_work(); + io_sq_thread_drop_mm_files();

if (cur_css) io_sq_thread_unassociate_blkcg();