[PATCH 3.11 038/137] 8021q: fix a potential memory leak

[Luis Henriques]

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

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

From: Li RongQing <roy.qing.li at gmail.com>

commit 916c1689a09bc1ca81f2d7a34876f8d35aadd11b upstream.

skb_cow called in vlan_reorder_header does not free the skb when it failed,
and vlan_reorder_header returns NULL to reset original skb when it is called
in vlan_untag, lead to a memory leak.

Signed-off-by: Li RongQing <roy.qing.li at gmail.com>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/8021q/vlan_core.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index 6ee48aac776f..7e57135c7cc4 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -108,8 +108,11 @@ EXPORT_SYMBOL(vlan_dev_vlan_id);
 
 static struct sk_buff *vlan_reorder_header(struct sk_buff *skb)
 {
-	if (skb_cow(skb, skb_headroom(skb)) < 0)
+	if (skb_cow(skb, skb_headroom(skb)) < 0) {
+		kfree_skb(skb);
 		return NULL;
+	}
+
 	memmove(skb->data - ETH_HLEN, skb->data - VLAN_ETH_HLEN, 2 * ETH_ALEN);
 	skb->mac_header += VLAN_HLEN;
 	return skb;
-- 
1.9.1