[PATCH 4.3 016/125] tun_dst: Fix potential NULL dereference

[Greg Kroah-Hartman]

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

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

From: Tobias Klauser <tklauser@xxxxxxxxxx>

[ Upstream commit f63ce5b6fa5e9a0faf7a0e1ef2993a502878c78a ]

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@xxxxxxxxxx>
Signed-off-by: Tobias Klauser <tklauser@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 include/net/dst_metadata.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/include/net/dst_metadata.h
+++ b/include/net/dst_metadata.h
@@ -63,12 +63,13 @@ static inline struct metadata_dst *tun_r
 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);


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