From: Pavel Begunkov asml.silence@gmail.com
[ Upstream commit f1d96a8fcbbbb22d4fbc1d69eaaa678bbb0ff6e2 ]
Processing links, io_submit_sqe() prepares requests, drops sqes, and passes them with sqe=NULL to io_queue_sqe(). There IOSQE_DRAIN and/or IOSQE_ASYNC requests will go through the same prep, which doesn't expect sqe=NULL and fail with NULL pointer deference.
Always do full prepare including io_alloc_async_ctx() for linked requests, and then it can skip the second preparation.
Cc: stable@vger.kernel.org # 5.5 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 --- fs/io_uring.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 44ae2641b4b06..faa0198c99ffd 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3098,6 +3098,9 @@ static int io_req_defer_prep(struct io_kiocb *req, { ssize_t ret = 0;
+ if (!sqe) + return 0; + switch (req->opcode) { case IORING_OP_NOP: break; @@ -3681,6 +3684,11 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe, req->flags |= REQ_F_HARDLINK;
INIT_LIST_HEAD(&req->link_list); + + if (io_alloc_async_ctx(req)) { + ret = -EAGAIN; + goto err_req; + } ret = io_req_defer_prep(req, sqe); if (ret) req->flags |= REQ_F_FAIL_LINK;