From: Ido Schimmel Date: Thu, 6 Aug 2015 14:41:58 +0000 (+0200) Subject: mlxsw: Fix use-after-free bug in mlxsw_sx_port_xmit X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e577516b9db3e0f19df82b6430fe3b06e05d6304;p=linux-beck.git 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 Signed-off-by: Jiri Pirko Signed-off-by: David S. Miller --- diff --git a/drivers/net/ethernet/mellanox/mlxsw/switchx2.c b/drivers/net/ethernet/mellanox/mlxsw/switchx2.c index fce9b453433b..3e52ee93438c 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);