netdev - [PATCH net-next] mlxsw: spectrum_ptp: Fix validation in mlxsw_sp1_ptp_packet

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Date:   Tue, 2 Jul 2019 19:06:47 +0000
From:   Petr Machata <petrm@...lanox.com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Petr Machata <petrm@...lanox.com>,
        Colin Ian King <colin.king@...onical.com>,
        Ido Schimmel <idosch@...lanox.com>
Subject: [PATCH net-next] mlxsw: spectrum_ptp: Fix validation in
 mlxsw_sp1_ptp_packet_finish()

Before mlxsw_sp1_ptp_packet_finish() sends the packet back, it validates
whether the corresponding port is still valid. However the condition is
incorrect: when mlxsw_sp_port == NULL, the code dereferences the port to
compare it to skb->dev.

The condition needs to check whether the port is present and skb->dev still
refers to that port (or else is NULL). If that does not hold, bail out.
Add a pair of parentheses to fix the condition.

Fixes: d92e4e6e33c8 ("mlxsw: spectrum: PTP: Support timestamping on Spectrum-1")
Reported-by: Colin Ian King <colin.king@...onical.com>
Signed-off-by: Petr Machata <petrm@...lanox.com>
Signed-off-by: Colin Ian King <colin.king@...onical.com>
Reviewed-by: Ido Schimmel <idosch@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c
index 7d42f86237cd..437023d67a3b 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c
@@ -425,7 +425,7 @@ static void mlxsw_sp1_ptp_packet_finish(struct mlxsw_sp *mlxsw_sp,
 	 * split). Also make sure the SKB device reference is still valid.
 	 */
 	mlxsw_sp_port = mlxsw_sp->ports[local_port];
-	if (!mlxsw_sp_port && (!skb->dev || skb->dev == mlxsw_sp_port->dev)) {
+	if (!(mlxsw_sp_port && (!skb->dev || skb->dev == mlxsw_sp_port->dev))) {
 		dev_kfree_skb_any(skb);
 		return;
 	}
-- 
2.20.1