sch_sfq: add sanity check for the packet length

The packet length should be checked before the packet data is dereferenced.

Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 9 deletions

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index c65762823f5e..e85352b5c88d 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -122,7 +122,11 @@ static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
         switch (skb->protocol) {
         case htons(ETH_P_IP):
         {
-                const struct iphdr *iph = ip_hdr(skb);
+                const struct iphdr *iph;
+
+                if (!pskb_network_may_pull(skb, sizeof(*iph)))
+                        goto err;
+                iph = ip_hdr(skb);
                 h = (__force u32)iph->daddr;
                 h2 = (__force u32)iph->saddr ^ iph->protocol;
                 if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
@@ -131,25 +135,32 @@ static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
                      iph->protocol == IPPROTO_UDPLITE ||
                      iph->protocol == IPPROTO_SCTP ||
                      iph->protocol == IPPROTO_DCCP ||
-                     iph->protocol == IPPROTO_ESP))
+                     iph->protocol == IPPROTO_ESP) &&
+                     pskb_network_may_pull(skb, iph->ihl * 4 + 4))
                         h2 ^= *(((u32*)iph) + iph->ihl);
                 break;
         }
         case htons(ETH_P_IPV6):
         {
-                struct ipv6hdr *iph = ipv6_hdr(skb);
+                struct ipv6hdr *iph;
+
+                if (!pskb_network_may_pull(skb, sizeof(*iph)))
+                        goto err;
+                iph = ipv6_hdr(skb);
                 h = (__force u32)iph->daddr.s6_addr32[3];
                 h2 = (__force u32)iph->saddr.s6_addr32[3] ^ iph->nexthdr;
-                if (iph->nexthdr == IPPROTO_TCP ||
-                    iph->nexthdr == IPPROTO_UDP ||
-                    iph->nexthdr == IPPROTO_UDPLITE ||
-                    iph->nexthdr == IPPROTO_SCTP ||
-                    iph->nexthdr == IPPROTO_DCCP ||
-                    iph->nexthdr == IPPROTO_ESP)
+                if ((iph->nexthdr == IPPROTO_TCP ||
+                     iph->nexthdr == IPPROTO_UDP ||
+                     iph->nexthdr == IPPROTO_UDPLITE ||
+                     iph->nexthdr == IPPROTO_SCTP ||
+                     iph->nexthdr == IPPROTO_DCCP ||
+                     iph->nexthdr == IPPROTO_ESP) &&
+                    pskb_network_may_pull(skb, sizeof(*iph) + 4))
                         h2 ^= *(u32*)&iph[1];
                 break;
         }
         default:
+err:
                 h = (unsigned long)skb_dst(skb) ^ (__force u32)skb->protocol;
                 h2 = (unsigned long)skb->sk;
         }