The caller of io_cqring_event_overflow() should be holding the
completion_lock, which is violated by io_msg_tw_complete. There
is only one caller of io_add_aux_cqe(), so just add locking there
for now.
WARNING: CPU: 0 PID: 5145 at io_uring/io_uring.c:703 io_cqring_event_overflow+0x442/0x660 io_uring/io_uring.c:703
RIP: 0010:io_cqring_event_overflow+0x442/0x660 io_uring/io_uring.c:703
<TASK>
__io_post_aux_cqe io_uring/io_uring.c:816 [inline]
io_add_aux_cqe+0x27c/0x320 io_uring/io_uring.c:837
io_msg_tw_complete+0x9d/0x4d0 io_uring/msg_ring.c:78
io_fallback_req_func+0xce/0x1c0 io_uring/io_uring.c:256
process_one_work kernel/workqueue.c:3224 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3305
worker_thread+0x86d/0xd40 kernel/workqueue.c:3383
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:144
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Fixes: f33096a3c9 ("io_uring: add io_add_aux_cqe() helper")
Reported-by: syzbot+f7f9c893345c5c615d34@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c7350d07fefe8cce32b50f57665edbb6355ea8c1.1719927398.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
3b7c16be30