xfrm6: fix a potential use after free in xfrm6_policy.c

pskb_may_pull() maybe change skb->data and make nh and exthdr pointer
oboslete, so recompute the nd and exthdr

Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Li RongQing 2014-10-22 17:09:53 +08:00 committed by David S. Miller
parent 8751b12cd9
commit 789f202326

View File

@ -170,8 +170,10 @@ _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
case IPPROTO_DCCP: case IPPROTO_DCCP:
if (!onlyproto && (nh + offset + 4 < skb->data || if (!onlyproto && (nh + offset + 4 < skb->data ||
pskb_may_pull(skb, nh + offset + 4 - skb->data))) { pskb_may_pull(skb, nh + offset + 4 - skb->data))) {
__be16 *ports = (__be16 *)exthdr; __be16 *ports;
nh = skb_network_header(skb);
ports = (__be16 *)(nh + offset);
fl6->fl6_sport = ports[!!reverse]; fl6->fl6_sport = ports[!!reverse];
fl6->fl6_dport = ports[!reverse]; fl6->fl6_dport = ports[!reverse];
} }
@ -180,8 +182,10 @@ _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
case IPPROTO_ICMPV6: case IPPROTO_ICMPV6:
if (!onlyproto && pskb_may_pull(skb, nh + offset + 2 - skb->data)) { if (!onlyproto && pskb_may_pull(skb, nh + offset + 2 - skb->data)) {
u8 *icmp = (u8 *)exthdr; u8 *icmp;
nh = skb_network_header(skb);
icmp = (u8 *)(nh + offset);
fl6->fl6_icmp_type = icmp[0]; fl6->fl6_icmp_type = icmp[0];
fl6->fl6_icmp_code = icmp[1]; fl6->fl6_icmp_code = icmp[1];
} }
@ -192,8 +196,9 @@ _decode_session6(struct sk_buff *skb, struct flowi *fl, int reverse)
case IPPROTO_MH: case IPPROTO_MH:
if (!onlyproto && pskb_may_pull(skb, nh + offset + 3 - skb->data)) { if (!onlyproto && pskb_may_pull(skb, nh + offset + 3 - skb->data)) {
struct ip6_mh *mh; struct ip6_mh *mh;
mh = (struct ip6_mh *)exthdr;
nh = skb_network_header(skb);
mh = (struct ip6_mh *)(nh + offset);
fl6->fl6_mh_type = mh->ip6mh_type; fl6->fl6_mh_type = mh->ip6mh_type;
} }
fl6->flowi6_proto = nexthdr; fl6->flowi6_proto = nexthdr;