From: Tobias Klauser <tklauser@distanz.ch>
Date: Wed, 4 Nov 2015 12:49:49 +0000 (+0100)
Subject: tun_dst: Fix potential NULL dereference
X-Git-Tag: v4.4-rc1~45^2~36
X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=f63ce5b6fa5e9a0faf7a0e1ef2993a502878c78a

tun_dst: Fix potential NULL dereference

In tun_dst_unclone() the return value of skb_metadata_dst() is checked
for being NULL after it is dereferenced. Fix this by moving the
dereference after the NULL check.

Found by the Coverity scanner (CID 1338068).

Fixes: fc4099f17240 ("openvswitch: Fix egress tunnel info.")
Cc: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/net/dst_metadata.h b/include/net/dst_metadata.h
index ce009710120c..6816f0fa5693 100644
--- a/include/net/dst_metadata.h
+++ b/include/net/dst_metadata.h
@@ -63,12 +63,13 @@ static inline struct metadata_dst *tun_rx_dst(int md_size)
 static inline struct metadata_dst *tun_dst_unclone(struct sk_buff *skb)
 {
 	struct metadata_dst *md_dst = skb_metadata_dst(skb);
-	int md_size = md_dst->u.tun_info.options_len;
+	int md_size;
 	struct metadata_dst *new_md;
 
 	if (!md_dst)
 		return ERR_PTR(-EINVAL);
 
+	md_size = md_dst->u.tun_info.options_len;
 	new_md = metadata_dst_alloc(md_size, GFP_ATOMIC);
 	if (!new_md)
 		return ERR_PTR(-ENOMEM);