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dccp: Fix incorrect length check for ICMPv4 packets

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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 <yjwei@cn.fujitsu.com>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
This commit is contained in:
Wei Yongjun 2008-07-26 11:59:10 +01:00 committed by Gerrit Renker
parent e0bcfb0c6a
commit 18e1d83600
1 changed files with 4 additions and 3 deletions
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7
net/dccp/ipv4.c
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@ -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;
}