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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, Tong Zhang <ztong0001@gmail.com>,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 27/53] can: c_can_pci: c_can_pci_remove(): fix use-after-free
Date:   Mon, 29 Mar 2021 09:58:02 +0200
Message-Id: <20210329075608.425577390@linuxfoundation.org>
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From: Tong Zhang <ztong0001@gmail.com>

[ Upstream commit 0429d6d89f97ebff4f17f13f5b5069c66bde8138 ]

There is a UAF in c_can_pci_remove(). dev is released by
free_c_can_dev() and is used by pci_iounmap(pdev, priv->base) later.
To fix this issue, save the mmio address before releasing dev.

Fixes: 5b92da0443c2 ("c_can_pci: generic module for C_CAN/D_CAN on PCI")
Link: https://lore.kernel.org/r/20210301024512.539039-1-ztong0001@gmail.com
Signed-off-by: Tong Zhang <ztong0001@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/can/c_can/c_can_pci.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/c_can/c_can_pci.c b/drivers/net/can/c_can/c_can_pci.c
index d065c0e2d18e..f3e0b2124a37 100644
--- a/drivers/net/can/c_can/c_can_pci.c
+++ b/drivers/net/can/c_can/c_can_pci.c
@@ -239,12 +239,13 @@ static void c_can_pci_remove(struct pci_dev *pdev)
 {
 	struct net_device *dev = pci_get_drvdata(pdev);
 	struct c_can_priv *priv = netdev_priv(dev);
+	void __iomem *addr = priv->base;
 
 	unregister_c_can_dev(dev);
 
 	free_c_can_dev(dev);
 
-	pci_iounmap(pdev, priv->base);
+	pci_iounmap(pdev, addr);
 	pci_disable_msi(pdev);
 	pci_clear_master(pdev);
 	pci_release_regions(pdev);
-- 
2.30.1