linux-kernel - [PATCH] usb: musb: sunxi: Explicitly release USB PHY on exit

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Date:   Tue, 26 Sep 2017 21:39:23 +1000
From:   Jonathan Liu <net147@...il.com>
To:     Bin Liu <b-liu@...com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>
Cc:     linux-usb@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com,
        Jonathan Liu <net147@...il.com>
Subject: [PATCH] usb: musb: sunxi: Explicitly release USB PHY on exit

This fixes a kernel oops when unloading the driver due to usb_put_phy
being called after usb_phy_generic_unregister when the device is
detached. Calling usb_phy_generic_unregister causes x->dev->driver to
be NULL in usb_put_phy and results in a NULL pointer dereference.

As we are now explicitly managing the lifetime of usb_phy,
devm_usb_get_phy is changed to usb_get_phy and we call usb_put_phy in
the probe error path.

Cc: stable@...r.kernel.org # v4.3+
Signed-off-by: Jonathan Liu <net147@...il.com>
---
 drivers/usb/musb/sunxi.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/musb/sunxi.c b/drivers/usb/musb/sunxi.c
index c9a09b5bb6e5..8eed61042103 100644
--- a/drivers/usb/musb/sunxi.c
+++ b/drivers/usb/musb/sunxi.c
@@ -297,6 +297,8 @@ static int sunxi_musb_exit(struct musb *musb)
 	if (test_bit(SUNXI_MUSB_FL_HAS_SRAM, &glue->flags))
 		sunxi_sram_release(musb->controller->parent);
 
+	usb_put_phy(glue->xceiv);
+
 	return 0;
 }
 
@@ -781,7 +783,7 @@ static int sunxi_musb_probe(struct platform_device *pdev)
 		return PTR_ERR(glue->usb_phy);
 	}
 
-	glue->xceiv = devm_usb_get_phy(&pdev->dev, USB_PHY_TYPE_USB2);
+	glue->xceiv = usb_get_phy(USB_PHY_TYPE_USB2);
 	if (IS_ERR(glue->xceiv)) {
 		ret = PTR_ERR(glue->xceiv);
 		dev_err(&pdev->dev, "Error getting usb-phy %d\n", ret);
@@ -803,11 +805,13 @@ static int sunxi_musb_probe(struct platform_device *pdev)
 	if (IS_ERR(glue->musb_pdev)) {
 		ret = PTR_ERR(glue->musb_pdev);
 		dev_err(&pdev->dev, "Error registering musb dev: %d\n", ret);
-		goto err_unregister_usb_phy;
+		goto err_put_usb_phy;
 	}
 
 	return 0;
 
+err_put_usb_phy:
+	usb_put_phy(glue->xceiv);
 err_unregister_usb_phy:
 	usb_phy_generic_unregister(glue->usb_phy);
 	return ret;
-- 
2.13.2