[PATCH 3.12 08/78] net: mvneta: fix race condition in mvneta_tx()

[Jiri Slaby]

From: Eric Dumazet <edumazet@xxxxxxxxxx>

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

===============

[ 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: Jiri Slaby <jslaby@xxxxxxx>
---
 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 0e38db6469fb..9c66d3168911 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -1524,6 +1524,7 @@ static int mvneta_tx(struct sk_buff *skb, struct net_device *dev)
 	struct mvneta_tx_queue *txq = &pp->txqs[txq_id];
 	struct mvneta_tx_desc *tx_desc;
 	struct netdev_queue *nq;
+	int len = skb->len;
 	int frags = 0;
 	u32 tx_cmd;
 
@@ -1584,7 +1585,7 @@ out:
 	if (frags > 0) {
 		u64_stats_update_begin(&pp->tx_stats.syncp);
 		pp->tx_stats.packets++;
-		pp->tx_stats.bytes += skb->len;
+		pp->tx_stats.bytes += len;
 		u64_stats_update_end(&pp->tx_stats.syncp);
 
 	} else {
-- 
2.2.1

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