From da8c87241c26aac81a64c7e4d21d438a33018f4e Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Thu, 21 Feb 2013 23:32:27 +0000 Subject: [PATCH] vlan: adjust vlan_set_encap_proto() for its callers There are two places to call vlan_set_encap_proto(): vlan_untag() and __pop_vlan_tci(). vlan_untag() assumes skb->data points after mac addr, otherwise the following code vhdr = (struct vlan_hdr *) skb->data; vlan_tci = ntohs(vhdr->h_vlan_TCI); __vlan_hwaccel_put_tag(skb, vlan_tci); skb_pull_rcsum(skb, VLAN_HLEN); won't be correct. But __pop_vlan_tci() assumes points _before_ mac addr. In vlan_set_encap_proto(), it looks for some magic L2 value after mac addr: rawp = skb->data; if (*(unsigned short *) rawp == 0xFFFF) ... Therefore __pop_vlan_tci() is obviously wrong. A quick fix is avoiding using skb->data in vlan_set_encap_proto(), use 'vhdr+1' is always correct in both cases. Cc: David S. Miller Cc: Jesse Gross Signed-off-by: Cong Wang Acked-by: Jesse Gross Signed-off-by: David S. Miller --- include/linux/if_vlan.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h index d06cc5c8f58c..218a3b686d90 100644 --- a/include/linux/if_vlan.h +++ b/include/linux/if_vlan.h @@ -331,7 +331,7 @@ static inline void vlan_set_encap_proto(struct sk_buff *skb, struct vlan_hdr *vhdr) { __be16 proto; - unsigned char *rawp; + unsigned short *rawp; /* * Was a VLAN packet, grab the encapsulated protocol, which the layer @@ -344,8 +344,8 @@ static inline void vlan_set_encap_proto(struct sk_buff *skb, return; } - rawp = skb->data; - if (*(unsigned short *) rawp == 0xFFFF) + rawp = (unsigned short *)(vhdr + 1); + if (*rawp == 0xFFFF) /* * This is a magic hack to spot IPX packets. Older Novell * breaks the protocol design and runs IPX over 802.3 without -- 2.39.5