netdev - [PATCH net-next v2 1/4] Fix null pointer dereference in UDP uncompression function

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Message-Id: <1341550225-13112-2-git-send-email-tony.cheneau@amnesiak.org>
Date:	Fri,  6 Jul 2012 00:50:22 -0400
From:	Tony Cheneau <tony.cheneau@...esiak.org>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org,
	Alexander Smirnov <alex.bluesman.smirnov@...il.com>
Subject: [PATCH net-next v2 1/4] Fix null pointer dereference in UDP uncompression function

When a UDP packet gets fragmented, a crash will occur at reassembly time.
This is because skb->transport_header is not set during earlier period of fragment reassembly.
As a consequence, call to udp_hdr() return NULL and uh (which is NULL) gets
dereferenced without much test.

---
 net/ieee802154/6lowpan.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/net/ieee802154/6lowpan.c b/net/ieee802154/6lowpan.c
index f4070e5..07fa200 100644
--- a/net/ieee802154/6lowpan.c
+++ b/net/ieee802154/6lowpan.c
@@ -314,6 +314,9 @@ lowpan_uncompress_udp_header(struct sk_buff *skb)
 {
 	struct udphdr *uh = udp_hdr(skb);
 	u8 tmp;
+
+	if (!uh)
+		goto err;
 
 	if (lowpan_fetch_skb_u8(skb, &tmp))
 		goto err;
-- 
1.7.3.4

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