Subject: [PATCH 33/52] net: sched: ife: check on metadata length

From: Alexander Aring <[email-masked]>
Date: Fri, 20 Apr 2018 15:15:05 -0400

[ 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 <[email-masked]>
Reviewed-by: Yotam Gigi <[email-masked]>
Acked-by: Jamal Hadi Salim <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 net/ife/ife.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ife/ife.c b/net/ife/ife.c
index 7fbe70a0af4b..13bbf8cb6a39 100644
--- 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;
-- 
2.14.3