8021q: fix a potential memory leak

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@gmail.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index 9012b1c922b6..75d427763992 100644
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -114,8 +114,11 @@ EXPORT_SYMBOL(vlan_dev_vlan_proto);
 
 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;