Commit 968953df authored by Eric Dumazet's avatar Eric Dumazet Committed by Ben Hutchings

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

[ Upstream commit 1aa9d1a0 ]

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>
[bwh: Backported to 3.16: use offsetof() + sizeof() instead of
 offsetofend()]
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 46b1ffd4
......@@ -83,7 +83,7 @@ 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;
......@@ -91,12 +91,13 @@ 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_BH(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(offsetof(struct dccp_hdr, dccph_sport) + sizeof(dh->dccph_sport) > 8);
BUILD_BUG_ON(offsetof(struct dccp_hdr, dccph_dport) + sizeof(dh->dccph_dport) > 8);
dh = (struct dccp_hdr *)(skb->data + offset);
sk = inet6_lookup(net, &dccp_hashinfo,
&hdr->daddr, dh->dccph_dport,
......
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