[PATCH] io_uring/net: ensure io_send() recycles buffers for -EAGAIN retry

[PATCH] io_uring/net: ensure io_send() recycles buffers for -EAGAIN retry

[Jens Axboe]

If io_send() is using bundles or ring provided buffers in general, then
it must call io_kbuf_recycle() for the -EAGAIN case that ends up punting
to polling. If not, a later send could potentially pick a later buffer
and complete before the previous buffer, if space has freed up in the
socket and it races with poll retry of the previous send.

Link: https://github.com/axboe/liburing/discussions/1528
Cc: stable@vger.kernel.org
Fixes: a05d1f625c7a ("io_uring/net: support bundles for send")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/io_uring/net.c b/io_uring/net.c
index 519ea055b761..b1c3b86539ee 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -673,8 +673,10 @@ int io_send(struct io_kiocb *req, unsigned int issue_flags)
 	kmsg->msg.msg_flags = flags;
 	ret = sock_sendmsg(sock, &kmsg->msg);
 	if (ret < min_ret) {
-		if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
+		if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK)) {
+			io_kbuf_recycle(req, sel.buf_list, issue_flags);
 			return -EAGAIN;
+		}
 
 		if (ret > 0 && io_net_retry(sock, flags)) {
 			sr->len -= ret;

-- 
Jens Axboe