linux-kernel - [PATCH 4.4 42/67] net: pktgen: fix null ptr deref in skb allocation

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Message-Id: <20160127180912.310279544@linuxfoundation.org>
Date:	Wed, 27 Jan 2016 10:12:36 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	John Fastabend <john.r.fastabend@...el.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 42/67] net: pktgen: fix null ptr deref in skb allocation

4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: John Fastabend <john.fastabend@...il.com>

[ Upstream commit 3de03596dfeee48bc803c1d1a6daf60a459929f3 ]

Fix possible null pointer dereference that may occur when calling
skb_reserve() on a null skb.

Fixes: 879c7220e82 ("net: pktgen: Observe needed_headroom of the device")
Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/core/pktgen.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -2787,7 +2787,9 @@ static struct sk_buff *pktgen_alloc_skb(
 	} else {
 		 skb = __netdev_alloc_skb(dev, size, GFP_NOWAIT);
 	}
-	skb_reserve(skb, LL_RESERVED_SPACE(dev));
+
+	if (likely(skb))
+		skb_reserve(skb, LL_RESERVED_SPACE(dev));
 
 	return skb;
 }