net: sched: ife: check on metadata length

[ Upstream commit d57493d6d1be26c8ac8516a4463bfe24956978eb ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ife/ife.c b/net/ife/ife.c
index 7fbe70a0af4becb24204f47dfb47133d2591d44b..13bbf8cb6a3961d422d01cf5b16a724d16107419 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;