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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Roi Dayan <roid@nvidia.com>,
        Maor Dickman <maord@nvidia.com>,
        Saeed Mahameed <saeedm@nvidia.com>
Subject: [PATCH 5.12 125/296] net/mlx5e: Fix null deref accessing lag dev
Date:   Mon, 31 May 2021 15:13:00 +0200
Message-Id: <20210531130708.104524951@linuxfoundation.org>
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From: Roi Dayan <roid@nvidia.com>

commit 83026d83186bc48bb41ee4872f339b83f31dfc55 upstream.

It could be the lag dev is null so stop processing the event.
In bond_enslave() the active/backup slave being set before setting the
upper dev so first event is without an upper dev.
After setting the upper dev with bond_master_upper_dev_link() there is
a second event and in that event we have an upper dev.

Fixes: 7e51891a237f ("net/mlx5e: Use netdev events to set/del egress acl forward-to-vport rule")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/mellanox/mlx5/core/en/rep/bond.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en/rep/bond.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/rep/bond.c
@@ -223,6 +223,8 @@ static void mlx5e_rep_changelowerstate_e
 	rpriv = priv->ppriv;
 	fwd_vport_num = rpriv->rep->vport;
 	lag_dev = netdev_master_upper_dev_get(netdev);
+	if (!lag_dev)
+		return;
 
 	netdev_dbg(netdev, "lag_dev(%s)'s slave vport(%d) is txable(%d)\n",
 		   lag_dev->name, fwd_vport_num, net_lag_port_dev_txable(netdev));