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Commit 1aa9d1a0 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv6: dccp: fix out of bound access in dccp_v6_err() 



dccp_v6_err() does not use pskb_may_pull() and might access garbage.

We only need 4 bytes at the beginning of the DCCP header, like TCP,
so the 8 bytes pulled in icmpv6_notify() are more than enough.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 93636d1f

net/dccp/ipv6.c

+8 −7
Original line number Diff line number Diff line
@@ -70,7 +70,7 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 
			u8 type, u8 code, int offset, __be32 info)

{

	const struct ipv6hdr *hdr = (const struct ipv6hdr *)skb->data;

	const struct dccp_hdr *dh = (struct dccp_hdr *)(skb->data + offset);

	const struct dccp_hdr *dh;

	struct dccp_sock *dp;

	struct ipv6_pinfo *np;

	struct sock *sk;
@@ -78,12 +78,13 @@ static void dccp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 
	__u64 seq;

	struct net *net = dev_net(skb->dev);



	if (skb->len < offset + sizeof(*dh) ||

	    skb->len < offset + __dccp_basic_hdr_len(dh)) {

		__ICMP6_INC_STATS(net, __in6_dev_get(skb->dev),

				  ICMP6_MIB_INERRORS);

		return;

	}

	/* Only need dccph_dport & dccph_sport which are the first

	 * 4 bytes in dccp header.

	 * Our caller (icmpv6_notify()) already pulled 8 bytes for us.

	 */

	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);



	sk = __inet6_lookup_established(net, &dccp_hashinfo,

					&hdr->daddr, dh->dccph_dport,