From 74dcfcd1d3e332607a985344316ccf5d0c6ef0af Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 4 Dec 2019 08:53:43 -0700 Subject: io_uring: ensure req->submit is copied when req is deferred MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There's an issue with deferred requests through drain, where if we do need to defer, we're not copying over the sqe_submit state correctly. This can result in using uninitialized data when we then later go and submit the deferred request, like this check in __io_submit_sqe(): if (unlikely(s->index >= ctx->sq_entries)) return -EINVAL; with 's' being uninitialized, we can randomly fail this check. Fix this by copying sqe_submit state when we defer a request. Because it was fixed as part of a cleanup series in mainline, before anyone realized we had this issue. That removed the separate states of ->index vs ->submit.sqe. That series is not something I was comfortable putting into stable, hence the much simpler addition. Here's the patch in the series that fixes the same issue: commit cf6fd4bd559ee61a4454b161863c8de6f30f8dca Author: Pavel Begunkov Date: Mon Nov 25 23:14:39 2019 +0300 io_uring: inline struct sqe_submit Reported-by: Andres Freund Reported-by: Tomáš Chaloupka Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/io_uring.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'fs/io_uring.c') diff --git a/fs/io_uring.c b/fs/io_uring.c index b75c292f5559..a340147387ec 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2039,7 +2039,7 @@ add: } static int io_req_defer(struct io_ring_ctx *ctx, struct io_kiocb *req, - const struct io_uring_sqe *sqe) + struct sqe_submit *s) { struct io_uring_sqe *sqe_copy; @@ -2057,7 +2057,8 @@ static int io_req_defer(struct io_ring_ctx *ctx, struct io_kiocb *req, return 0; } - memcpy(sqe_copy, sqe, sizeof(*sqe_copy)); + memcpy(&req->submit, s, sizeof(*s)); + memcpy(sqe_copy, s->sqe, sizeof(*sqe_copy)); req->submit.sqe = sqe_copy; INIT_WORK(&req->work, io_sq_wq_submit_work); @@ -2425,7 +2426,7 @@ static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, { int ret; - ret = io_req_defer(ctx, req, s->sqe); + ret = io_req_defer(ctx, req, s); if (ret) { if (ret != -EIOCBQUEUED) { io_free_req(req); @@ -2452,7 +2453,7 @@ static int io_queue_link_head(struct io_ring_ctx *ctx, struct io_kiocb *req, * list. */ req->flags |= REQ_F_IO_DRAIN; - ret = io_req_defer(ctx, req, s->sqe); + ret = io_req_defer(ctx, req, s); if (ret) { if (ret != -EIOCBQUEUED) { io_free_req(req); -- cgit v1.2.3