From e577516b9db3e0f19df82b6430fe3b06e05d6304 Mon Sep 17 00:00:00 2001
From: Ido Schimmel <idosch@mellanox.com>
Date: Thu, 6 Aug 2015 16:41:58 +0200
Subject: [PATCH] mlxsw: Fix use-after-free bug in mlxsw_sx_port_xmit
Store the length of the skb before transmitting it and use it for stats
instead of skb->len, since skb might have been freed already.
This issue was discovered using the Kernel Address sanitizer (KASan).
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/net/ethernet/mellanox/mlxsw/switchx2.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mellanox/mlxsw/switchx2.c b/drivers/net/ethernet/mellanox/mlxsw/switchx2.c
index fce9b453433b5..3e52ee93438c0 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/switchx2.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/switchx2.c
@@ -300,6 +300,7 @@ static netdev_tx_t mlxsw_sx_port_xmit(struct sk_buff *skb,
.local_port = mlxsw_sx_port->local_port,
.is_emad = false,
};
+ u64 len;
int err;
if (mlxsw_core_skb_transmit_busy(mlxsw_sx, &tx_info))
@@ -316,6 +317,7 @@ static netdev_tx_t mlxsw_sx_port_xmit(struct sk_buff *skb,
}
}
mlxsw_sx_txhdr_construct(skb, &tx_info);
+ len = skb->len;
/* Due to a race we might fail here because of a full queue. In that
* unlikely case we simply drop the packet.
*/
@@ -325,7 +327,7 @@ static netdev_tx_t mlxsw_sx_port_xmit(struct sk_buff *skb,
pcpu_stats = this_cpu_ptr(mlxsw_sx_port->pcpu_stats);
u64_stats_update_begin(&pcpu_stats->syncp);
pcpu_stats->tx_packets++;
- pcpu_stats->tx_bytes += skb->len;
+ pcpu_stats->tx_bytes += len;
u64_stats_update_end(&pcpu_stats->syncp);
} else {
this_cpu_inc(mlxsw_sx_port->pcpu_stats->tx_dropped);
--
2.39.5