From: Miaohe Lin linmiaohe@huawei.com
[ Upstream commit 55eff0eb7460c3d50716ed9eccf22257b046ca92 ]
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: 0d5501c1c828 ("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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/skbuff.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5421,8 +5421,8 @@ struct sk_buff *skb_vlan_untag(struct sk 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;