This is a note to let you know that I've just added the patch titled
l2tp: pass correct message length to ip6_append_data
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:
l2tp-pass-correct-message-length-to-ip6_append_data.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 359e54a93ab43d32ee1bff3c2f9f10cb9f6b6e79 Mon Sep 17 00:00:00 2001
From: Tom Parkin <tparkin@xxxxxxxxxxx>
Date: Tue, 20 Feb 2024 12:21:56 +0000
Subject: l2tp: pass correct message length to ip6_append_data
From: Tom Parkin <tparkin@xxxxxxxxxxx>
commit 359e54a93ab43d32ee1bff3c2f9f10cb9f6b6e79 upstream.
l2tp_ip6_sendmsg needs to avoid accounting for the transport header
twice when splicing more data into an already partially-occupied skbuff.
To manage this, we check whether the skbuff contains data using
skb_queue_empty when deciding how much data to append using
ip6_append_data.
However, the code which performed the calculation was incorrect:
ulen = len + skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0;
..due to C operator precedence, this ends up setting ulen to
transhdrlen for messages with a non-zero length, which results in
corrupted packets on the wire.
Add parentheses to correct the calculation in line with the original
intent.
Fixes: 9d4c75800f61 ("ipv4, ipv6: Fix handling of transhdrlen in __ip{,6}_append_data()")
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Tom Parkin <tparkin@xxxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240220122156.43131-1-tparkin@xxxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/l2tp/l2tp_ip6.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -628,7 +628,7 @@ static int l2tp_ip6_sendmsg(struct sock
back_from_confirm:
lock_sock(sk);
- ulen = len + skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0;
+ ulen = len + (skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0);
err = ip6_append_data(sk, ip_generic_getfrag, msg,
ulen, transhdrlen, &ipc6,
&fl6, (struct rt6_info *)dst,
Patches currently in stable-queue which might be from tparkin@xxxxxxxxxxx are
queue-5.10/l2tp-pass-correct-message-length-to-ip6_append_data.patch
