From: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> mainline inclusion from mainline-5.11-rc1 commit c07e6719511e77c4b289f62bfe96423eb6ea061d category: bugfix bugzilla: 182869 CVE: NA --------------------------- io_iopoll_complete() does not hold completion_lock to complete polled io, so in io_wq_submit_work(), we can not call io_req_complete() directly, to complete polled io, otherwise there maybe concurrent access to cqring, defer_list, etc, which is not safe. Commit dad1b1242fd5 ("io_uring: always let io_iopoll_complete() complete polled io") has fixed this issue, but Pavel reported that IOPOLL apart from rw can do buf reg/unreg requests( IORING_OP_PROVIDE_BUFFERS or IORING_OP_REMOVE_BUFFERS), so the fix is not good. Given that io_iopoll_complete() is always called under uring_lock, so here for polled io, we can also get uring_lock to fix this issue. Fixes: dad1b1242fd5 ("io_uring: always let io_iopoll_complete() complete polled io") Cc: <stable@vger.kernel.org> # 5.5+ Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> [axboe: don't deref 'req' after completing it'] Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Reviewed-by: Yang Erkun <yangerkun@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- fs/io_uring.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index c944a27178a48..b5fb86e2ed597 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5782,19 +5782,28 @@ static struct io_wq_work *io_wq_submit_work(struct io_wq_work *work) } if (ret) { + struct io_ring_ctx *lock_ctx = NULL; + + if (req->ctx->flags & IORING_SETUP_IOPOLL) + lock_ctx = req->ctx; + /* - * io_iopoll_complete() does not hold completion_lock to complete - * polled io, so here for polled io, just mark it done and still let - * io_iopoll_complete() complete it. + * io_iopoll_complete() does not hold completion_lock to + * complete polled io, so here for polled io, we can not call + * io_req_complete() directly, otherwise there maybe concurrent + * access to cqring, defer_list, etc, which is not safe. Given + * that io_iopoll_complete() is always called under uring_lock, + * so here for polled io, we also get uring_lock to complete + * it. */ - if (req->ctx->flags & IORING_SETUP_IOPOLL) { - struct kiocb *kiocb = &req->rw.kiocb; + if (lock_ctx) + mutex_lock(&lock_ctx->uring_lock); - kiocb_done(kiocb, ret, NULL); - } else { - req_set_fail_links(req); - io_req_complete(req, ret); - } + req_set_fail_links(req); + io_req_complete(req, ret); + + if (lock_ctx) + mutex_unlock(&lock_ctx->uring_lock); } return io_steal_work(req); -- 2.25.1