netdev - [PATCH 2/4] connector: use nlmsg_len() to check message length

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Message-Id: <1380571389-15343-3-git-send-email-minipli@googlemail.com>
Date:	Mon, 30 Sep 2013 22:03:07 +0200
From:	Mathias Krause <minipli@...glemail.com>
To:	Evgeniy Polyakov <zbr@...emap.net>
Cc:	Mathias Krause <minipli@...glemail.com>, netdev@...r.kernel.org
Subject: [PATCH 2/4] connector: use nlmsg_len() to check message length

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.

Cc: stable@...r.kernel.org  # v2.6.14+
Signed-off-by: Mathias Krause <minipli@...glemail.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 6ecfa75..0daa11e 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_HDRLEN) {
 		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) {
 			kfree_skb(skb);
 			return;
 		}
-- 
1.7.10.4

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