linux-kernel - [PATCH 2/4] USB: omap_udc: fix crashes on probe error and module removal

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Date:   Sun, 18 Nov 2018 21:59:10 +0200
From:   Aaro Koskinen <aaro.koskinen@....fi>
To:     Felipe Balbi <balbi@...nel.org>, linux-usb@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
        Tony Lindgren <tony@...mide.com>,
        Aaro Koskinen <aaro.koskinen@....fi>
Subject: [PATCH 2/4] USB: omap_udc: fix crashes on probe error and module removal

We currently crash if usb_add_gadget_udc_release() fails, since the
udc->done is not initialized until in the remove function. Furthermore, on
module removal the udc data is accessed although the release function
is already triggered by usb_del_gadget_udc() early in the function.
Fix by releasing the data manually.

The patch fixes omap_udc module probe with a failing gadged, and also
allows the removal of omap_udc. Tested by running "modprobe omap_udc;
modprobe -r omap_udc" in a loop.

Signed-off-by: Aaro Koskinen <aaro.koskinen@....fi>
---
 drivers/usb/gadget/udc/omap_udc.c | 15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/gadget/udc/omap_udc.c b/drivers/usb/gadget/udc/omap_udc.c
index 1c77218c82af..d98782ec254d 100644
--- a/drivers/usb/gadget/udc/omap_udc.c
+++ b/drivers/usb/gadget/udc/omap_udc.c
@@ -2591,9 +2591,8 @@ omap_ep_setup(char *name, u8 addr, u8 type,
 	return buf;
 }
 
-static void omap_udc_release(struct device *dev)
+static void omap_udc_release(void)
 {
-	complete(udc->done);
 	kfree(udc);
 	udc = NULL;
 }
@@ -2900,16 +2899,14 @@ static int omap_udc_probe(struct platform_device *pdev)
 	}
 
 	create_proc_file();
-	status = usb_add_gadget_udc_release(&pdev->dev, &udc->gadget,
-			omap_udc_release);
+	status = usb_add_gadget_udc(&pdev->dev, &udc->gadget);
 	if (!status)
 		return 0;
 
 	remove_proc_file();
 
 cleanup1:
-	kfree(udc);
-	udc = NULL;
+	omap_udc_release();
 
 cleanup0:
 	if (!IS_ERR_OR_NULL(xceiv))
@@ -2930,8 +2927,6 @@ static int omap_udc_probe(struct platform_device *pdev)
 
 static int omap_udc_remove(struct platform_device *pdev)
 {
-	DECLARE_COMPLETION_ONSTACK(done);
-
 	if (!udc)
 		return -ENODEV;
 
@@ -2939,8 +2934,6 @@ static int omap_udc_remove(struct platform_device *pdev)
 	if (udc->driver)
 		return -EBUSY;
 
-	udc->done = &done;
-
 	pullup_disable(udc);
 	if (!IS_ERR_OR_NULL(udc->transceiver)) {
 		usb_put_phy(udc->transceiver);
@@ -2960,7 +2953,7 @@ static int omap_udc_remove(struct platform_device *pdev)
 	release_mem_region(pdev->resource[0].start,
 			pdev->resource[0].end - pdev->resource[0].start + 1);
 
-	wait_for_completion(&done);
+	omap_udc_release();
 
 	return 0;
 }
-- 
2.17.0