netdev - [PATCH net] tun_dst: Fix potential NULL dereference

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Message-Id: <1446641389-26183-1-git-send-email-tklauser@distanz.ch>
Date:	Wed,  4 Nov 2015 13:49:49 +0100
From:	Tobias Klauser <tklauser@...tanz.ch>
To:	"David S. Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, Pravin B Shelar <pshelar@...ira.com>
Subject: [PATCH net] 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@...ira.com>
Signed-off-by: Tobias Klauser <tklauser@...tanz.ch>
---
 include/net/dst_metadata.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/dst_metadata.h b/include/net/dst_metadata.h
index ce00971..6816f0f 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);
-- 
2.6.1.148.g7927db1

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