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net: Fix potential wrong skb->protocol in skb_vlan_untag()

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We may access the two bytes after vlan_hdr in vlan_set_encap_proto(). So
we should pull VLAN_HLEN + sizeof(unsigned short) in skb_vlan_untag() or
we may access the wrong data.

Fixes: 0d5501c1c8 ("net: Always untag vlan-tagged traffic on input.")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Miaohe Lin 2020-08-15 04:44:31 -04:00 committed by David S. Miller
parent f8414a8d88
commit 55eff0eb74
1 changed files with 2 additions and 2 deletions
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4
net/core/skbuff.c
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@ -5418,8 +5418,8 @@ struct sk_buff *skb_vlan_untag(struct sk_buff *skb)
skb = skb_share_check(skb, GFP_ATOMIC);
if (unlikely(!skb))
goto err_free;
if (unlikely(!pskb_may_pull(skb, VLAN_HLEN)))
/* We may access the two bytes after vlan_hdr in vlan_set_encap_proto(). */
if (unlikely(!pskb_may_pull(skb, VLAN_HLEN + sizeof(unsigned short))))
goto err_free;
vhdr = (struct vlan_hdr *)skb->data;