net: sched: ife: check on metadata length

This patch checks if sk buffer is available to dererence ife header. If
not then NULL will returned to signal an malformed ife packet. This
avoids to crashing the kernel from outside.

Signed-off-by: Alexander Aring <aring@mojatatu.com>
Reviewed-by: Yotam Gigi <yotam.gi@gmail.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ife/ife.c b/net/ife/ife.c
index 7fbe70a..13bbf8c 100644 (file)
--- a/net/ife/ife.c
+++ b/net/ife/ife.c
@@ -69,6 +69,9 @@ void *ife_decode(struct sk_buff *skb, u16 *metalen)
        int total_pull;
        u16 ifehdrln;
 
+       if (!pskb_may_pull(skb, skb->dev->hard_header_len + IFE_METAHDRLEN))
+               return NULL;
+
        ifehdr = (struct ifeheadr *) (skb->data + skb->dev->hard_header_len);
        ifehdrln = ntohs(ifehdr->metalen);
        total_pull = skb->dev->hard_header_len + ifehdrln;