linux-kernel - [PATCH 5.10 135/663] net: enetc: fix destroyed phylink dereference during unbind

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Date:   Mon,  1 Mar 2021 17:06:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vladimir Oltean <vladimir.oltean@....com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 135/663] net: enetc: fix destroyed phylink dereference during unbind

From: Vladimir Oltean <vladimir.oltean@....com>

[ Upstream commit 3af409ca278d4a8d50e91f9f7c4c33b175645cf3 ]

The following call path suggests that calling unregister_netdev on an
interface that is up will first bring it down.

enetc_pf_remove
-> unregister_netdev
   -> unregister_netdevice_queue
      -> unregister_netdevice_many
         -> dev_close_many
            -> __dev_close_many
               -> enetc_close
                  -> enetc_stop
                     -> phylink_stop

However, enetc first destroys the phylink instance, then calls
unregister_netdev. This is already dissimilar to the setup (and error
path teardown path) from enetc_pf_probe, but more than that, it is buggy
because it is invalid to call phylink_stop after phylink_destroy.

So let's first unregister the netdev (and let the .ndo_stop events
consume themselves), then destroy the phylink instance, then free the
netdev.

Fixes: 71b77a7a27a3 ("enetc: Migrate to PHYLINK and PCS_LYNX")
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/ethernet/freescale/enetc/enetc_pf.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/freescale/enetc/enetc_pf.c b/drivers/net/ethernet/freescale/enetc/enetc_pf.c
index 06514af0df106..796e3d6f23f09 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_pf.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc_pf.c
@@ -1164,14 +1164,15 @@ static void enetc_pf_remove(struct pci_dev *pdev)
 	struct enetc_ndev_priv *priv;
 
 	priv = netdev_priv(si->ndev);
-	enetc_phylink_destroy(priv);
-	enetc_mdiobus_destroy(pf);
 
 	if (pf->num_vfs)
 		enetc_sriov_configure(pdev, 0);
 
 	unregister_netdev(si->ndev);
 
+	enetc_phylink_destroy(priv);
+	enetc_mdiobus_destroy(pf);
+
 	enetc_free_msix(priv);
 
 	enetc_free_si_resources(priv);
-- 
2.27.0