From: Wei Yongjun Date: Sat, 26 Jul 2008 10:59:10 +0000 (+0100) Subject: dccp: Fix incorrect length check for ICMPv4 packets X-Git-Tag: v2.6.27-rc1~33^2~1^2~1 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=18e1d836002ad970f42736bad09b7be9cfe99545;p=linux-2.6 dccp: Fix incorrect length check for ICMPv4 packets Unlike TCP, which only needs 8 octets of original packet data, DCCP requires minimally 12 or 16 bytes for ICMP-payload sequence number checks. This patch replaces the insufficient length constant of 8 with a two-stage test, making sure that 12 bytes are available, before computing the basic header length required for sequence number checks. Signed-off-by: Wei Yongjun Signed-off-by: Gerrit Renker --- diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index 6a2f1879e1..882c5c4de6 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -196,8 +196,8 @@ static inline void dccp_do_pmtu_discovery(struct sock *sk, static void dccp_v4_err(struct sk_buff *skb, u32 info) { const struct iphdr *iph = (struct iphdr *)skb->data; - const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + - (iph->ihl << 2)); + const u8 offset = iph->ihl << 2; + const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset); struct dccp_sock *dp; struct inet_sock *inet; const int type = icmp_hdr(skb)->type; @@ -207,7 +207,8 @@ static void dccp_v4_err(struct sk_buff *skb, u32 info) int err; struct net *net = dev_net(skb->dev); - if (skb->len < (iph->ihl << 2) + 8) { + if (skb->len < offset + sizeof(*dh) || + skb->len < offset + __dccp_basic_hdr_len(dh)) { ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS); return; }