From 38fc96a58ce40257aec79b32e9b310c86907c63c Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Sat, 28 Dec 2024 17:44:52 +0000 Subject: [PATCH] io_uring/rw: fix downgraded mshot read The io-wq path can downgrade a multishot request to oneshot mode, however io_read_mshot() doesn't handle that and would still post multiple CQEs. That's not allowed, because io_req_post_cqe() requires stricter context requirements. The described can only happen with pollable files that don't support FMODE_NOWAIT, which is an odd combination, so if even allowed it should be fairly rare. Cc: stable@vger.kernel.org Reported-by: chase xd Fixes: bee1d5becdf5b ("io_uring: disable io-wq execution of multishot NOWAIT requests") Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/c5c8c4a50a882fd581257b81bf52eee260ac29fd.1735407848.git.asml.silence@gmail.com Signed-off-by: Jens Axboe --- io_uring/rw.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/io_uring/rw.c b/io_uring/rw.c index 0bcb83e4ce3cf..29bb3010f9c06 100644 --- a/io_uring/rw.c +++ b/io_uring/rw.c @@ -983,6 +983,8 @@ int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags) io_kbuf_recycle(req, issue_flags); if (ret < 0) req_set_fail(req); + } else if (!(req->flags & REQ_F_APOLL_MULTISHOT)) { + cflags = io_put_kbuf(req, ret, issue_flags); } else { /* * Any successful return value will keep the multishot read -- 2.39.5