This is a note to let you know that I've just added the patch titled
io_uring/net: save msghdr->msg_control for retries
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
io_uring-net-save-msghdr-msg_control-for-retries.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 76513d9f99764e6acf9f0e2e53b7d42d95d6630d Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@xxxxxxxxx>
Date: Fri, 23 Jun 2023 07:38:14 -0600
Subject: io_uring/net: save msghdr->msg_control for retries
From: Jens Axboe <axboe@xxxxxxxxx>
Commit cac9e4418f4cbd548ccb065b3adcafe073f7f7d2 upstream.
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@xxxxxxxxxxxxxxx # 5.10+
Link: https://github.com/axboe/liburing/issues/880
Reported-and-tested-by: Marek Majkowski <marek@xxxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
io_uring/io_uring.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -581,6 +581,7 @@ struct io_sr_msg {
size_t len;
size_t done_io;
struct io_buffer *kbuf;
+ void __user *msg_control;
};
struct io_open {
@@ -4718,10 +4719,16 @@ static int io_setup_async_msg(struct io_
static int io_sendmsg_copy_hdr(struct io_kiocb *req,
struct io_async_msghdr *iomsg)
{
+ struct io_sr_msg *sr = &req->sr_msg;
+ int ret;
+
iomsg->msg.msg_name = &iomsg->addr;
iomsg->free_iov = iomsg->fast_iov;
- return sendmsg_copy_msghdr(&iomsg->msg, req->sr_msg.umsg,
+ ret = sendmsg_copy_msghdr(&iomsg->msg, req->sr_msg.umsg,
req->sr_msg.msg_flags, &iomsg->free_iov);
+ /* save msg_control as sys_sendmsg() overwrites it */
+ sr->msg_control = iomsg->msg.msg_control;
+ return ret;
}
static int io_sendmsg_prep_async(struct io_kiocb *req)
@@ -4778,6 +4785,8 @@ static int io_sendmsg(struct io_kiocb *r
if (ret)
return ret;
kmsg = &iomsg;
+ } else {
+ kmsg->msg.msg_control = sr->msg_control;
}
flags = req->sr_msg.msg_flags;
Patches currently in stable-queue which might be from axboe@xxxxxxxxx are
queue-5.10/io_uring-net-clear-msg_controllen-on-partial-sendmsg-retry.patch
queue-5.10/io_uring-net-disable-partial-retries-for-recvmsg-with-cmsg.patch
queue-5.10/io_uring-net-save-msghdr-msg_control-for-retries.patch
