io_uring/waitid: always prune wait queue entry in io_waitid_wait()

commit 2f8229d53d984c6a05b71ac9e9583d4354e3b91f upstream.

For a successful return, always remove our entry from the wait queue
entry list. Previously this was skipped if a cancelation was in
progress, but this can race with another invocation of the wait queue
entry callback.

Cc: stable@vger.kernel.org
Fixes: f31ecf671d ("io_uring: add IORING_OP_WAITID support")
Reported-by: syzbot+b9e83021d9c642a33d8c@syzkaller.appspotmail.com
Tested-by: syzbot+b9e83021d9c642a33d8c@syzkaller.appspotmail.com
Link: https://lore.kernel.org/io-uring/68e5195e.050a0220.256323.001f.GAE@google.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jens Axboe 2025-10-07 07:46:00 -06:00 committed by Greg Kroah-Hartman
parent 37bd91f227
commit 696ba60320

View File

@ -272,13 +272,14 @@ static int io_waitid_wait(struct wait_queue_entry *wait, unsigned mode,
if (!pid_child_should_wake(wo, p))
return 0;
list_del_init(&wait->entry);
/* cancel is in progress */
if (atomic_fetch_inc(&iw->refs) & IO_WAITID_REF_MASK)
return 1;
req->io_task_work.func = io_waitid_cb;
io_req_task_work_add(req);
list_del_init(&wait->entry);
return 1;
}