[3.11.y.z extended stable] Patch "arc_emac: fix potential use after free" has been added to staging queue

[Luis Henriques]

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

    arc_emac: fix potential use after free

to the linux-3.11.y-queue branch of the 3.11.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-3.11.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 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From dcc23074d2d7163781e3237e5e0ae5c44766816f Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet at gmail.com>
Date: Thu, 19 Dec 2013 18:10:40 -0800
Subject: arc_emac: fix potential use after free

commit 37ec274e9713eafc2ba6c4471420f06cb8f68ecf upstream.

Signed-off-by: Eric Dumazet <edumazet at google.com>

skb_tx_timestamp(skb) should be called _before_ TX completion
has a chance to trigger, otherwise it is too late and we access
freed memory.

Fixes: e4f2379db6c6 ("ethernet/arc/arc_emac - Add new driver")
From: Eric Dumazet <edumazet at google.com>
Cc: Alexey Brodkin <Alexey.Brodkin at synopsys.com>
Cc: Richard Cochran <richardcochran at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/ethernet/arc/emac_main.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
index 9e16014..4fc96d6 100644
--- a/drivers/net/ethernet/arc/emac_main.c
+++ b/drivers/net/ethernet/arc/emac_main.c
@@ -565,6 +565,8 @@ static int arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
 	/* Make sure pointer to data buffer is set */
 	wmb();

+	skb_tx_timestamp(skb);
+
 	*info = cpu_to_le32(FOR_EMAC | FIRST_OR_LAST_MASK | len);

 	/* Increment index to point to the next BD */
@@ -579,8 +581,6 @@ static int arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)

 	arc_reg_set(priv, R_STATUS, TXPL_MASK);

-	skb_tx_timestamp(skb);
-
 	return NETDEV_TX_OK;
 }

--
1.8.3.2