io_uring/net: restore msg_control on sendzc retry

cac9e44 ("io_uring/net: save msghdr->msg_control for retries")
reinstatiates msg_control before every __sys_sendmsg_sock(), since the
function can overwrite the value in msghdr. We need to do same for
zerocopy sendmsg.

Cc: stable@vger.kernel.org
Fixes: 493108d ("io_uring/net: zerocopy sendmsg")
Link: axboe/liburing#1067
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/cc1d5d9df0576fa66ddad4420d240a98a020b267.1712596179.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: isilence

io_uring/net.c

@@ -1276,6 +1276,7 @@ int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (req_has_async_data(req)) {
 		kmsg = req->async_data;
+		kmsg->msg.msg_control_user = sr->msg_control;
 	} else {
 		ret = io_sendmsg_copy_hdr(req, &iomsg);
 		if (ret)