linux-kernel - [PATCH v4 1/7] media: uvcvideo: Fix crash during unbind if gpio unit is in use

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Message-Id: <20241125-uvc-subdev-v4-1-51e040599f1a@chromium.org>
Date: Mon, 25 Nov 2024 19:49:06 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, linux-media@...r.kernel.org, 
 Yunke Cao <yunkec@...omium.org>, Hans Verkuil <hverkuil@...all.nl>, 
 Hans de Goede <hdegoede@...hat.com>, Ricardo Ribalda <ribalda@...omium.org>, 
 stable@...r.kernel.org
Subject: [PATCH v4 1/7] media: uvcvideo: Fix crash during unbind if gpio
 unit is in use

We used the wrong device for the device managed functions. We used the
usb device, when we should be using the interface device.

If we unbind the driver from the usb interface, the cleanup functions
are never called. In our case, the IRQ is never disabled.

If an IRQ is triggered, it will try to access memory sections that are
already free, causing an OOPS.

We cannot use the function devm_request_threaded_irq here. The devm_*
clean functions may be called after the main structure is released by
uvc_delete.

Luckily this bug has small impact, as it is only affected by devices
with gpio units and the user has to unbind the device, a disconnect will
not trigger this error.

Cc: stable@...r.kernel.org
Fixes: 2886477ff987 ("media: uvcvideo: Implement UVC_EXT_GPIO_UNIT")
Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 28 +++++++++++++++++++++-------
 drivers/media/usb/uvc/uvcvideo.h   |  1 +
 2 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index faf5386cb061..6d34c910a659 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1295,14 +1295,14 @@ static int uvc_gpio_parse(struct uvc_device *dev)
 	struct gpio_desc *gpio_privacy;
 	int irq;
 
-	gpio_privacy = devm_gpiod_get_optional(&dev->udev->dev, "privacy",
+	gpio_privacy = devm_gpiod_get_optional(&dev->intf->dev, "privacy",
 					       GPIOD_IN);
 	if (IS_ERR_OR_NULL(gpio_privacy))
 		return PTR_ERR_OR_ZERO(gpio_privacy);
 
 	irq = gpiod_to_irq(gpio_privacy);
 	if (irq < 0)
-		return dev_err_probe(&dev->udev->dev, irq,
+		return dev_err_probe(&dev->intf->dev, irq,
 				     "No IRQ for privacy GPIO\n");
 
 	unit = uvc_alloc_new_entity(dev, UVC_EXT_GPIO_UNIT,
@@ -1329,15 +1329,27 @@ static int uvc_gpio_parse(struct uvc_device *dev)
 static int uvc_gpio_init_irq(struct uvc_device *dev)
 {
 	struct uvc_entity *unit = dev->gpio_unit;
+	int ret;
 
 	if (!unit || unit->gpio.irq < 0)
 		return 0;
 
-	return devm_request_threaded_irq(&dev->udev->dev, unit->gpio.irq, NULL,
-					 uvc_gpio_irq,
-					 IRQF_ONESHOT | IRQF_TRIGGER_FALLING |
-					 IRQF_TRIGGER_RISING,
-					 "uvc_privacy_gpio", dev);
+	ret = request_threaded_irq(unit->gpio.irq, NULL, uvc_gpio_irq,
+				   IRQF_ONESHOT | IRQF_TRIGGER_FALLING |
+				   IRQF_TRIGGER_RISING,
+				   "uvc_privacy_gpio", dev);
+
+	unit->gpio.initialized = !ret;
+
+	return ret;
+}
+
+static void uvc_gpio_deinit(struct uvc_device *dev)
+{
+	if (!dev->gpio_unit || !dev->gpio_unit->gpio.initialized)
+		return;
+
+	free_irq(dev->gpio_unit->gpio.irq, dev);
 }
 
 /* ------------------------------------------------------------------------
@@ -1934,6 +1946,8 @@ static void uvc_unregister_video(struct uvc_device *dev)
 {
 	struct uvc_streaming *stream;
 
+	uvc_gpio_deinit(dev);
+
 	list_for_each_entry(stream, &dev->streams, list) {
 		/* Nothing to do here, continue. */
 		if (!video_is_registered(&stream->vdev))
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 07f9921d83f2..965a789ed03e 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -234,6 +234,7 @@ struct uvc_entity {
 			u8  *bmControls;
 			struct gpio_desc *gpio_privacy;
 			int irq;
+			bool initialized;
 		} gpio;
 	};
 

-- 
2.47.0.338.g60cca15819-goog