linux-kernel - [PATCH 3.2 111/115] ipv4: l2tp: fix a potential issue in l2tp_ip

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1461711744.988727985@decadent.org.uk>
Date:	Wed, 27 Apr 2016 01:02:24 +0200
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Haishuang Yan" <yanhaishuang@...s.chinamobile.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.2 111/115] ipv4: l2tp: fix a potential issue in l2tp_ip_recv

3.2.80-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Haishuang Yan <yanhaishuang@...s.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@...s.chinamobile.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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
@@ -129,12 +129,11 @@ static int l2tp_ip_recv(struct sk_buff *
 	int length;
 	int offset;
 
-	/* 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;
 
@@ -162,6 +161,9 @@ 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;
 		printk(KERN_DEBUG "%s: ip recv: ", tunnel->name);
 
 		offset = 0;