io_uring: fix multishots with selected buffers

[ upstream commit d63b0e8a628e62ca85a0f7915230186bb92f8bb4 ]

We do io_kbuf_recycle() when arming a poll but every iteration of a
multishot can grab more buffers, which is why we need to flush the kbuf
ring state before continuing with waiting.

Cc: stable@vger.kernel.org
Fixes: b3fdea6ecb55c ("io_uring: multishot recv")
Reported-by: Muhammad Ramdhan <ramdhan@starlabs.sg>
Reported-by: Bing-Jhong Billy Jheng <billy@starlabs.sg>
Reported-by: Jacob Soo <jacob.soo@starlabs.sg>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1bfc9990fe435f1fc6152ca9efeba5eb3e68339c.1738025570.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/io_uring/poll.c b/io_uring/poll.c
index 428f84ed1021650e23b93f50703a025ca94c375f..bbdc9a7624a13b52bb218b983cd0c5da9e0ae9f2 100644 (file)
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -307,6 +307,8 @@ static int io_poll_check_events(struct io_kiocb *req, bool *locked)
                        }
                } else {
                        int ret = io_poll_issue(req, locked);
+                       io_kbuf_recycle(req, 0);
+
                        if (ret == IOU_STOP_MULTISHOT)
                                return IOU_POLL_REMOVE_POLL_USE_RES;
                        if (ret < 0)