From: =?UTF-8?q?Marek=20Beh=C3=BAn?= <kabel@kernel.org>
Date: Wed, 19 Jan 2022 17:27:48 +0100
Subject: phylib: fix potential use-after-free
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Patch-mainline: v5.17-rc2
Git-commit: cbda1b16687580d5beee38273f6241ae3725960c
References: bsc#1119113 FATE#326472

Commit bafbdd527d56 ("phylib: Add device reset GPIO support") added call
to phy_device_reset(phydev) after the put_device() call in phy_detach().

The comment before the put_device() call says that the phydev might go
away with put_device().

Fix potential use-after-free by calling phy_device_reset() before
put_device().

Fixes: bafbdd527d56 ("phylib: Add device reset GPIO support")
Signed-off-by: Marek Behún <kabel@kernel.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220119162748.32418-1-kabel@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/phy/phy_device.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1160,6 +1160,9 @@ void phy_detach(struct phy_device *phyde
 	    phydev->mdio.dev.driver == &genphy_driver.mdiodrv.driver)
 		device_release_driver(&phydev->mdio.dev);
 
+	/* Assert the reset signal */
+	phy_device_reset(phydev, 1);
+
 	/*
 	 * The phydev might go away on the put_device() below, so avoid
 	 * a use-after-free bug by reading the underlying bus first.
@@ -1169,9 +1172,6 @@ void phy_detach(struct phy_device *phyde
 	put_device(&phydev->mdio.dev);
 	if (ndev_owner != bus->owner)
 		module_put(bus->owner);
-
-	/* Assert the reset signal */
-	phy_device_reset(phydev, 1);
 }
 EXPORT_SYMBOL(phy_detach);