net: fec: fix potential use after free

[ 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@google.com>
Fixes: de5fb0a05348 ("net: fec: put tx to napi poll function to fix dead lock")
Cc: Frank Li <Frank.Li@freescale.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index d48099f03b7f619b15959a4f4fd2b4db2b491805..fbd0d7df67d8dec64f712602cb0c17e3cb585e2b 100644 (file)
--- 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, struct net_device *ndev)
        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, struct net_device *ndev)
        /* Trigger transmission start */
        writel(0, fep->hwp + FEC_X_DES_ACTIVE);
 
-       skb_tx_timestamp(skb);
-
        return NETDEV_TX_OK;
 }