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@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index 6ecfa758942c..0daa11e418b1 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;
                 }