dccp: Fix out of bounds access in DCCP error handler

[linux-2.6-microblaze.git] / net / dccp / ipv4.c

diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index a545ad7..a5361fb 100644 (file)
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -255,12 +255,17 @@ static int dccp_v4_err(struct sk_buff *skb, u32 info)
        int err;
        struct net *net = dev_net(skb->dev);
 
-       /* Only need dccph_dport & dccph_sport which are the first
-        * 4 bytes in dccp header.
+       /* For the first __dccp_basic_hdr_len() check, we only need dh->dccph_x,
+        * which is in byte 7 of the dccp header.
         * Our caller (icmp_socket_deliver()) already pulled 8 bytes for us.
+        *
+        * Later on, we want to access the sequence number fields, which are
+        * beyond 8 bytes, so we have to pskb_may_pull() ourselves.
         */
-       BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_sport) > 8);
-       BUILD_BUG_ON(offsetofend(struct dccp_hdr, dccph_dport) > 8);
+       dh = (struct dccp_hdr *)(skb->data + offset);
+       if (!pskb_may_pull(skb, offset + __dccp_basic_hdr_len(dh)))
+               return -EINVAL;
+       iph = (struct iphdr *)skb->data;
        dh = (struct dccp_hdr *)(skb->data + offset);
 
        sk = __inet_lookup_established(net, &dccp_hashinfo,