Patch "ipv4: l2tp: fix a potential issue in l2tp_ip_recv" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ipv4: l2tp: fix a potential issue in l2tp_ip_recv

to the 4.4-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:
     ipv4-l2tp-fix-a-potential-issue-in-l2tp_ip_recv.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Sat Apr 16 10:02:53 PDT 2016
From: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Date: Sun, 3 Apr 2016 22:09:23 +0800
Subject: ipv4: l2tp: fix a potential issue in l2tp_ip_recv

From: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>

[ Upstream commit 5745b8232e942abd5e16e85fa9b27cc21324acf0 ]

pskb_may_pull() can change skb->data, so we have to load ptr/optr at the
right place.

Signed-off-by: Haishuang Yan <yanhaishuang@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/l2tp/l2tp_ip.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/net/l2tp/l2tp_ip.c
+++ b/net/l2tp/l2tp_ip.c
@@ -123,12 +123,11 @@ static int l2tp_ip_recv(struct sk_buff *
 	struct l2tp_tunnel *tunnel = NULL;
 	int length;
 
-	/* Point to L2TP header */
-	optr = ptr = skb->data;
-
 	if (!pskb_may_pull(skb, 4))
 		goto discard;
 
+	/* Point to L2TP header */
+	optr = ptr = skb->data;
 	session_id = ntohl(*((__be32 *) ptr));
 	ptr += 4;
 
@@ -156,6 +155,9 @@ static int l2tp_ip_recv(struct sk_buff *
 		if (!pskb_may_pull(skb, length))
 			goto discard;
 
+		/* Point to L2TP header */
+		optr = ptr = skb->data;
+		ptr += 4;
 		pr_debug("%s: ip recv\n", tunnel->name);
 		print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, ptr, length);
 	}


Patches currently in stable-queue which might be from yanhaishuang@cmss.chinamobile.com are

queue-4.4/bridge-allow-set-bridge-ageing-time-when-switchdev-disabled.patch
queue-4.4/ipv4-l2tp-fix-a-potential-issue-in-l2tp_ip_recv.patch
queue-4.4/ipv6-l2tp-fix-a-potential-issue-in-l2tp_ip6_recv.patch