[ 3.5.y.z extended stable ] Patch "vlan: adjust vlan_set_encap_proto() for its callers" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    vlan: adjust vlan_set_encap_proto() for its callers

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 516568fb94a6aed881f3e570d9ac38eb3bacdf92 Mon Sep 17 00:00:00 2001
From: Cong Wang <amwang at redhat.com>
Date: Thu, 21 Feb 2013 23:32:27 +0000
Subject: [PATCH] vlan: adjust vlan_set_encap_proto() for its callers

commit da8c87241c26aac81a64c7e4d21d438a33018f4e upstream.

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 <davem at davemloft.net>
Cc: Jesse Gross <jesse at nicira.com>
Signed-off-by: Cong Wang <amwang at redhat.com>
Acked-by: Jesse Gross <jesse at nicira.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 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 561e130..9b0c614 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -327,7 +327,7 @@ 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
@@ -340,8 +340,8 @@ 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
--
1.8.1.2