[PATCH 3.13.y-ckt 94/96] net: mvneta: fix race condition in mvneta_tx()

From: Kamal Mostafa
Date: Mon Dec 15 2014 - 14:40:23 EST

3.13.11-ckt13 -stable review patch. If anyone has any objections, please let me know.


From: Eric Dumazet <edumazet@xxxxxxxxxx>

[ Upstream commit 5f478b41033606d325e420df693162e2524c2b94 ]

mvneta_tx() dereferences skb to get skb->len too late,
as hardware might have completed the transmit and TX completion
could have freed the skb from another cpu.

Fixes: 71f6d1b31fb1 ("net: mvneta: replace Tx timer with a real interrupt")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
drivers/net/ethernet/marvell/mvneta.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 03ff7c2..453437b 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -1562,6 +1562,7 @@ static int mvneta_tx(struct sk_buff *skb, struct net_device *dev)
u16 txq_id = skb_get_queue_mapping(skb);
struct mvneta_tx_queue *txq = &pp->txqs[txq_id];
struct mvneta_tx_desc *tx_desc;
+ int len = skb->len;
struct netdev_queue *nq;
int frags = 0;
u32 tx_cmd;
@@ -1625,7 +1626,7 @@ out:

- stats->tx_bytes += skb->len;
+ stats->tx_bytes += len;
} else {

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