[v2.6.34-stable 12/77] gro: reset vlan_tci on reuse

[Paul Gortmaker]

From: Benjamin Poirier <bpoirier@xxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
    If you see a problem with using this for longterm, please comment.
                   -------------------

This one liner is part of upstream
commit 3701e51382a026cba10c60b03efabe534fba4ca4
Author: Jesse Gross <jesse@xxxxxxxxxx>

    vlan: Centralize handling of hardware acceleration.

The bulk of that commit is a rework of the hardware assisted vlan tagging
driver interface, and as such doesn't classify for -stable inclusion. The fix
that is needed is a part of that commit but can work independently of the
rest.

This patch can avoid panics on the 2.6.32.y -stable kernels and is in the same
spirit as mainline commits
66c46d7 gro: Reset dev pointer on reuse
6d152e2 gro: reset skb_iif on reuse
which are already in -stable.

For drivers using the vlan_gro_frags() interface, a packet with an invalid tci
leads to GRO_DROP and napi_reuse_skb(). The skb has to be sanitized before
being reused or we may send an skb with an invalid vlan_tci field up the stack
where it is not expected.

Signed-off-by: Benjamin Poirier <bpoirier@xxxxxxx>
Cc: Jesse Gross <jesse@xxxxxxxxxx>
Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>
[PG: taken from v2.6.32.y stable, commit 5aff28abc7e]
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 net/core/dev.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index 7daff00..2aaf2e6 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2823,6 +2823,7 @@ void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 {
 	__skb_pull(skb, skb_headlen(skb));
 	skb_reserve(skb, NET_IP_ALIGN - skb_headroom(skb));
+	skb->vlan_tci = 0;
 	skb->dev = napi->dev;
 	skb->skb_iif = 0;
 
-- 
1.7.12.1

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