FAILED: patch "[PATCH] io_uring/net: save msghdr->msg_control for retries" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x cac9e4418f4cbd548ccb065b3adcafe073f7f7d2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023061722-dock-bleep-55f8@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cac9e4418f4cbd548ccb065b3adcafe073f7f7d2 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 12 Jun 2023 13:51:36 -0600
Subject: [PATCH] io_uring/net: save msghdr->msg_control for retries

If the application sets ->msg_control and we have to later retry this
command, or if it got queued with IOSQE_ASYNC to begin with, then we
need to retain the original msg_control value. This is due to the net
stack overwriting this field with an in-kernel pointer, to copy it
in. Hitting that path for the second time will now fail the copy from
user, as it's attempting to copy from a non-user address.

Cc: stable@vger.kernel.org # 5.10+
Link: https://github.com/axboe/liburing/issues/880
Reported-and-tested-by: Marek Majkowski <marek@cloudflare.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/net.c b/io_uring/net.c
index 89e839013837..51b0f7fbb4f5 100644
--- a/io_uring/net.c
+++ b/io_uring/net.c
@@ -65,6 +65,7 @@ struct io_sr_msg {
 	u16				addr_len;
 	u16				buf_group;
 	void __user			*addr;
+	void __user			*msg_control;
 	/* used only for send zerocopy */
 	struct io_kiocb 		*notif;
 };
@@ -195,11 +196,15 @@ static int io_sendmsg_copy_hdr(struct io_kiocb *req,
 			       struct io_async_msghdr *iomsg)
 {
 	struct io_sr_msg *sr = io_kiocb_to_cmd(req, struct io_sr_msg);
+	int ret;
 
 	iomsg->msg.msg_name = &iomsg->addr;
 	iomsg->free_iov = iomsg->fast_iov;
-	return sendmsg_copy_msghdr(&iomsg->msg, sr->umsg, sr->msg_flags,
+	ret = sendmsg_copy_msghdr(&iomsg->msg, sr->umsg, sr->msg_flags,
 					&iomsg->free_iov);
+	/* save msg_control as sys_sendmsg() overwrites it */
+	sr->msg_control = iomsg->msg.msg_control;
+	return ret;
 }
 
 int io_send_prep_async(struct io_kiocb *req)
@@ -297,6 +302,7 @@ int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
 
 	if (req_has_async_data(req)) {
 		kmsg = req->async_data;
+		kmsg->msg.msg_control = sr->msg_control;
 	} else {
 		ret = io_sendmsg_copy_hdr(req, &iomsg);
 		if (ret)