netfilter: xt_TCPMSS: add more sanity tests on tcph->doff

[pandora-kernel.git] / net / netfilter / xt_TCPMSS.c

diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index 8d32468..0774164 100644 (file)
--- a/net/netfilter/xt_TCPMSS.c
+++ b/net/netfilter/xt_TCPMSS.c
@@ -59,7 +59,7 @@ tcpmss_mangle_packet(struct sk_buff *skb,
 
        /* This is a fragment, no TCP header is available */
        if (par->fragoff != 0)
-               return XT_CONTINUE;
+               return 0;
 
        if (!skb_make_writable(skb, skb->len))
                return -1;
@@ -71,7 +71,7 @@ tcpmss_mangle_packet(struct sk_buff *skb,
        tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff);
        tcp_hdrlen = tcph->doff * 4;
 
-       if (len < tcp_hdrlen)
+       if (len < tcp_hdrlen || tcp_hdrlen < sizeof(struct tcphdr))
                return -1;
 
        if (info->mss == XT_TCPMSS_CLAMP_PMTU) {
@@ -122,6 +122,10 @@ tcpmss_mangle_packet(struct sk_buff *skb,
        if (len > tcp_hdrlen)
                return 0;
 
+       /* tcph->doff has 4 bits, do not wrap it to 0 */
+       if (tcp_hdrlen >= 15 * 4)
+               return 0;
+
        /*
         * MSS Option not found ?! add it..
         */