netdev - [PATCH net 3/3] net: sched: ife: check on metadata length

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Message-Id: <20180418213534.6215-4-aring@mojatatu.com>
Date:   Wed, 18 Apr 2018 17:35:34 -0400
From:   Alexander Aring <aring@...atatu.com>
To:     yotam.gi@...il.com
Cc:     jhs@...atatu.com, davem@...emloft.net, xiyou.wangcong@...il.com,
        jiri@...nulli.us, yuvalm@...lanox.com, netdev@...r.kernel.org,
        kernel@...atatu.com, Alexander Aring <aring@...atatu.com>
Subject: [PATCH net 3/3] 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@...atatu.com>
---
 net/ife/ife.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ife/ife.c b/net/ife/ife.c
index 8632d2685efb..7c100034fbee 100644
--- a/net/ife/ife.c
+++ b/net/ife/ife.c
@@ -70,6 +70,9 @@ void *ife_decode(struct sk_buff *skb, u16 *metalen)
 	u16 ifehdrln;
 
 	ifehdr = (struct ifeheadr *) (skb->data + skb->dev->hard_header_len);
+	if (skb->len < skb->dev->hard_header_len + IFE_METAHDRLEN)
+		return NULL;
+
 	ifehdrln = ntohs(ifehdr->metalen);
 	total_pull = skb->dev->hard_header_len + ifehdrln;
 
-- 
2.11.0