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Commit 18e1d836 authored by Wei Yongjun's avatar Wei Yongjun Committed by Gerrit Renker
Browse files

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: default avatarWei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
parent e0bcfb0c

net/dccp/ipv4.c

+4 −3
Original line number Diff line number Diff line
@@ -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;

	}