From: Pavel Begunkov <asml.silence@gmail.com> 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/?i... -------------------------------- commit 544d163d659d45a206d8929370d5a2984e546cb7 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: syzbot+6805087452d72929404e@syzkaller.appspotmail.com Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> --- io_uring/io_uring.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index f33926715f57..b3ba5adc3ca7 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -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); } -- 2.39.2