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authorEric W. Biederman <ebiederm@xmission.com>2015-03-12 18:22:59 -0500
committerDavid S. Miller <davem@davemloft.net>2015-03-12 23:05:04 -0400
commit76fecd8275be6de76513430e7526825944ab932f (patch)
treec04917753aa8f8cd07d54140c9580af45c7f5dd8 /net/mpls
parent2c29b2354a06f42493ddd2a5eb65962981e666ed (diff)
downloadlinux-stericsson-76fecd8275be6de76513430e7526825944ab932f.tar.gz
mpls: In mpls_egress verify the packet length.
Reobert Shearman noticed that mpls_egress is failing to verify that the bytes to be examined are in fact present in the packet before mpls_egress reads those bytes. As suggested by David Miller reduce this to a single pskb_may_pull call so that we don't do unnecessary work in the fast path. Reported-by: Robert Shearman <rshearma@brocade.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/mpls')
-rw-r--r--net/mpls/af_mpls.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c
index 0ad8f7141be2..db8a2ea6d4de 100644
--- a/net/mpls/af_mpls.c
+++ b/net/mpls/af_mpls.c
@@ -92,9 +92,24 @@ static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
* The strange cases if we choose to support them will require
* manual configuration.
*/
- struct iphdr *hdr4 = ip_hdr(skb);
+ struct iphdr *hdr4;
bool success = true;
+ /* The IPv4 code below accesses through the IPv4 header
+ * checksum, which is 12 bytes into the packet.
+ * The IPv6 code below accesses through the IPv6 hop limit
+ * which is 8 bytes into the packet.
+ *
+ * For all supported cases there should always be at least 12
+ * bytes of packet data present. The IPv4 header is 20 bytes
+ * without options and the IPv6 header is always 40 bytes
+ * long.
+ */
+ if (!pskb_may_pull(skb, 12))
+ return false;
+
+ /* Use ip_hdr to find the ip protocol version */
+ hdr4 = ip_hdr(skb);
if (hdr4->version == 4) {
skb->protocol = htons(ETH_P_IP);
csum_replace2(&hdr4->check,