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mlxsw: Fix use-after-free bug in mlxsw_sx_port_xmit

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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>
This commit is contained in:
Ido Schimmel
2015-08-06 16:41:58 +02:00
committed by David S. Miller
parent 3bfcd34764
commit e577516b9d
1 changed files with 3 additions and 1 deletions
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4
drivers/net/ethernet/mellanox/mlxsw/switchx2.c
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@@ -300,6 +300,7 @@ static netdev_tx_t mlxsw_sx_port_xmit(struct sk_buff *skb,
.local_port = mlxsw_sx_port->local_port, .local_port = mlxsw_sx_port->local_port,
.is_emad = false, .is_emad = false,
}; };
u64 len;
int err; int err;
if (mlxsw_core_skb_transmit_busy(mlxsw_sx, &tx_info)) 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); 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 /* Due to a race we might fail here because of a full queue. In that
* unlikely case we simply drop the packet. * 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); pcpu_stats = this_cpu_ptr(mlxsw_sx_port->pcpu_stats);
u64_stats_update_begin(&pcpu_stats->syncp); u64_stats_update_begin(&pcpu_stats->syncp);
pcpu_stats->tx_packets++; pcpu_stats->tx_packets++;
pcpu_stats->tx_bytes += skb->len; pcpu_stats->tx_bytes += len;
u64_stats_update_end(&pcpu_stats->syncp); u64_stats_update_end(&pcpu_stats->syncp);
} else { } else {
this_cpu_inc(mlxsw_sx_port->pcpu_stats->tx_dropped); this_cpu_inc(mlxsw_sx_port->pcpu_stats->tx_dropped);