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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Alexander Aring <aring@mojatatu.com>,
        Yotam Gigi <yotam.gi@gmail.com>,
        Jamal Hadi Salim <jhs@mojatatu.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.16 40/81] net: sched: ife: check on metadata length
Date:   Fri, 27 Apr 2018 15:58:42 +0200
Message-Id: <20180427135745.421240664@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexander Aring <aring@mojatatu.com>


[ 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>
---
 net/ife/ife.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/ife/ife.c
+++ b/net/ife/ife.c
@@ -69,6 +69,9 @@ void *ife_decode(struct sk_buff *skb, u1
 	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;