io_uring: fix multishots with selected buffers

commit d63b0e8a628e62ca85a0f7915230186bb92f8bb4 upstream.

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 1f63b60e85e7c07a20e86441b5bd0ea8d7dcf016..17dea8aa09c9b3bbe2ef39372c395284e57b54da 100644 (file)
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -357,8 +357,10 @@ void io_poll_task_func(struct io_kiocb *req, struct io_tw_state *ts)
 
        ret = io_poll_check_events(req, ts);
        if (ret == IOU_POLL_NO_ACTION) {
+               io_kbuf_recycle(req, 0);
                return;
        } else if (ret == IOU_POLL_REQUEUE) {
+               io_kbuf_recycle(req, 0);
                __io_poll_execute(req, 0);
                return;
        }