[PATCH 3.10 25/62] net: fec: fix potential use after free

[Greg Kroah-Hartman]

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 7a2a84518cfb263d2c4171b3d63671f88316adb2 ]

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.

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Fixes: de5fb0a05348 ("net: fec: put tx to napi poll function to fix dead lock")
Cc: Frank Li <Frank.Li@xxxxxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Acked-by: Richard Cochran <richardcochran@xxxxxxxxx>
Acked-by: Frank Li <Frank.Li@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/ethernet/freescale/fec_main.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -371,6 +371,8 @@ fec_enet_start_xmit(struct sk_buff *skb,
 	else
 		bdp = fec_enet_get_nextdesc(bdp, fep->bufdesc_ex);
 
+	skb_tx_timestamp(skb);
+
 	fep->cur_tx = bdp;
 
 	if (fep->cur_tx == fep->dirty_tx)
@@ -379,8 +381,6 @@ fec_enet_start_xmit(struct sk_buff *skb,
 	/* Trigger transmission start */
 	writel(0, fep->hwp + FEC_X_DES_ACTIVE);
 
-	skb_tx_timestamp(skb);
-
 	return NETDEV_TX_OK;
 }
 


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