Commit 588b89ce authored by Pavel Begunkov's avatar Pavel Begunkov Committed by Zizhi Wo
Browse files

io_uring: lock overflowing for IOPOLL 

stable inclusion
from stable-v5.10.165
commit de77faee280163ff03b7ab64af6c9d779a43d4c4
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IALIEY
CVE: CVE-2023-52903

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=de77faee280163ff03b7ab64af6c9d779a43d4c4



--------------------------------

commit 544d163d upstream.

syzbot reports an issue with overflow filling for IOPOLL:

WARNING: CPU: 0 PID: 28 at io_uring/io_uring.c:734 io_cqring_event_overflow+0x1c0/0x230 io_uring/io_uring.c:734
CPU: 0 PID: 28 Comm: kworker/u4:1 Not tainted 6.2.0-rc3-syzkaller-16369-g358a161a6a9e #0
Workqueue: events_unbound io_ring_exit_work
Call trace:
 io_cqring_event_overflow+0x1c0/0x230 io_uring/io_uring.c:734
 io_req_cqe_overflow+0x5c/0x70 io_uring/io_uring.c:773
 io_fill_cqe_req io_uring/io_uring.h:168 [inline]
 io_do_iopoll+0x474/0x62c io_uring/rw.c:1065
 io_iopoll_try_reap_events+0x6c/0x108 io_uring/io_uring.c:1513
 io_uring_try_cancel_requests+0x13c/0x258 io_uring/io_uring.c:3056
 io_ring_exit_work+0xec/0x390 io_uring/io_uring.c:2869
 process_one_work+0x2d8/0x504 kernel/workqueue.c:2289
 worker_thread+0x340/0x610 kernel/workqueue.c:2436
 kthread+0x12c/0x158 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:863

There is no real problem for normal IOPOLL as flush is also called with
uring_lock taken, but it's getting more complicated for IOPOLL|SQPOLL,
for which __io_cqring_overflow_flush() happens from the CQ waiting path.

Reported-and-tested-by: default avatar <syzbot+6805087452d72929404e@syzkaller.appspotmail.com>
Cc: stable@vger.kernel.org # 5.10+
Signed-off-by: default avatarPavel Begunkov <asml.silence@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
Signed-off-by: default avatarZizhi Wo <wozizhi@huawei.com>
parent 36427360

io_uring/io_uring.c

+16 −2
Original line number Diff line number Diff line
@@ -2472,12 +2472,26 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events, 


	io_init_req_batch(&rb);

	while (!list_empty(done)) {

		struct io_uring_cqe *cqe;

		unsigned cflags;



		req = list_first_entry(done, struct io_kiocb, inflight_entry);

		list_del(&req->inflight_entry);



		io_fill_cqe_req(req, req->result, io_put_rw_kbuf(req));

		cflags = io_put_rw_kbuf(req);

		(*nr_events)++;



		cqe = io_get_cqe(ctx);

		if (cqe) {

			WRITE_ONCE(cqe->user_data, req->user_data);

			WRITE_ONCE(cqe->res, req->result);

			WRITE_ONCE(cqe->flags, cflags);

		} else {

			spin_lock(&ctx->completion_lock);

			io_cqring_event_overflow(ctx, req->user_data,

							req->result, cflags);

			spin_unlock(&ctx->completion_lock);

		}



		if (req_ref_put_and_test(req))

			io_req_free_batch(&rb, req, &ctx->submit_state);

	}