[IPV6]: Do no rely on skb->dst before it is assigned.
Because skb->dst is assigned in ip6_route_input(), it is really
bad to use it in hop-by-hop option handler(s).
Closes: Bug #8450 (Eric Sesterhenn <snakebyte@gmx.de>)
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 6d8e4ac..14be0b9 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -660,6 +660,14 @@
Hop-by-hop options.
**********************************/
+/*
+ * Note: we cannot rely on skb->dst before we assign it in ip6_route_input().
+ */
+static inline struct inet6_dev *ipv6_skb_idev(struct sk_buff *skb)
+{
+ return skb->dst ? ip6_dst_idev(skb->dst) : __in6_dev_get(skb->dev);
+}
+
/* Router Alert as of RFC 2711 */
static int ipv6_hop_ra(struct sk_buff **skbp, int optoff)
@@ -688,25 +696,25 @@
if (nh[optoff + 1] != 4 || (optoff & 3) != 2) {
LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_jumbo: wrong jumbo opt length/alignment %d\n",
nh[optoff+1]);
- IP6_INC_STATS_BH(ip6_dst_idev(skb->dst),
+ IP6_INC_STATS_BH(ipv6_skb_idev(skb),
IPSTATS_MIB_INHDRERRORS);
goto drop;
}
pkt_len = ntohl(*(__be32 *)(nh + optoff + 2));
if (pkt_len <= IPV6_MAXPLEN) {
- IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
+ IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff+2);
return 0;
}
if (ipv6_hdr(skb)->payload_len) {
- IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INHDRERRORS);
+ IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INHDRERRORS);
icmpv6_param_prob(skb, ICMPV6_HDR_FIELD, optoff);
return 0;
}
if (pkt_len > skb->len - sizeof(struct ipv6hdr)) {
- IP6_INC_STATS_BH(ip6_dst_idev(skb->dst), IPSTATS_MIB_INTRUNCATEDPKTS);
+ IP6_INC_STATS_BH(ipv6_skb_idev(skb), IPSTATS_MIB_INTRUNCATEDPKTS);
goto drop;
}