[3.8.y.z extended stable] Patch "connector: use nlmsg_len() to check message length" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Fri Nov 1 21:43:41 UTC 2013

This is a note to let you know that I have just added a patch titled

    connector: use nlmsg_len() to check message length

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see



>From f65fc6c5e2eecf8052fec3fdbec0d733260ccbdc Mon Sep 17 00:00:00 2001
From: Mathias Krause <minipli at googlemail.com>
Date: Mon, 30 Sep 2013 22:03:07 +0200
Subject: connector: use nlmsg_len() to check message length

[ Upstream commit 162b2bedc084d2d908a04c93383ba02348b648b0 ]

The current code tests the length of the whole netlink message to be
at least as long to fit a cn_msg. This is wrong as nlmsg_len includes
the length of the netlink message header. Use nlmsg_len() instead to
fix this "off-by-NLMSG_HDRLEN" size check.

Signed-off-by: Mathias Krause <minipli at googlemail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/connector/connector.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index 7b69591..3050b7e 100644
--- a/drivers/connector/connector.c
+++ b/drivers/connector/connector.c
@@ -157,17 +157,18 @@ static int cn_call_callback(struct sk_buff *skb)
 static void cn_rx_skb(struct sk_buff *__skb)
 	struct nlmsghdr *nlh;
-	int err;
 	struct sk_buff *skb;
+	int len, err;

 	skb = skb_get(__skb);

 	if (skb->len >= NLMSG_SPACE(0)) {
 		nlh = nlmsg_hdr(skb);
+		len = nlmsg_len(nlh);

-		if (nlh->nlmsg_len < sizeof(struct cn_msg) ||
+		if (len < (int)sizeof(struct cn_msg) ||
 		    skb->len < nlh->nlmsg_len ||
-		    nlh->nlmsg_len > CONNECTOR_MAX_MSG_SIZE) {
+		    len > CONNECTOR_MAX_MSG_SIZE) {

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