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,