[PATCH v2] media: uvcvideo: Fix crash during unbind if gpio unit is in use

[PATCH v2] media: uvcvideo: Fix crash during unbind if gpio unit is in use

[Ricardo Ribalda]

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.

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@vger.kernel.org
Fixes: 2886477ff987 ("media: uvcvideo: Implement UVC_EXT_GPIO_UNIT")
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
Changes in v2: Thanks to Laurent.
- The main structure is not allocated with devres so there is a small
  period of time where we can get an irq with the structure free. Do not
  use devres for the IRQ.
- Link to v1: https://lore.kernel.org/r/20241031-uvc-crashrmmod-v1-1-059fe593b1e6@chromium.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 a96f6ca0889f..af6aec27083c 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 +1329,28 @@ 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);
+
+	if (!ret)
+		dev->gpio_unit->gpio.inited = true;
+
+	return ret;
+}
+
+static void uvc_gpio_cleanup(struct uvc_device *dev)
+{
+	if (!dev->gpio_unit || !dev->gpio_unit->gpio.inited)
+		return;
+
+	free_irq(dev->gpio_unit->gpio.irq, dev);
 }
 
 /* ------------------------------------------------------------------------
@@ -1880,6 +1893,7 @@ static void uvc_delete(struct kref *kref)
 	struct uvc_device *dev = container_of(kref, struct uvc_device, ref);
 	struct list_head *p, *n;
 
+	uvc_gpio_cleanup(dev);
 	uvc_status_cleanup(dev);
 	uvc_ctrl_cleanup_device(dev);
 
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index 07f9921d83f2..376cd670539b 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 inited;
 		} gpio;
 	};
 

---
base-commit: c7ccf3683ac9746b263b0502255f5ce47f64fe0a
change-id: 20241031-uvc-crashrmmod-666de3fc9141

Best regards,
-- 
Ricardo Ribalda <ribalda@chromium.org>

Re: [PATCH v2] media: uvcvideo: Fix crash during unbind if gpio unit is in use

[Sakari Ailus]

Hi Ricardo,

Thanks for the update.

On Tue, Nov 05, 2024 at 10:53:59AM +0000, Ricardo Ribalda wrote:
> 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.
> 
> 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@vger.kernel.org
> Fixes: 2886477ff987 ("media: uvcvideo: Implement UVC_EXT_GPIO_UNIT")
> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
> Changes in v2: Thanks to Laurent.
> - The main structure is not allocated with devres so there is a small
>   period of time where we can get an irq with the structure free. Do not
>   use devres for the IRQ.
> - Link to v1: https://lore.kernel.org/r/20241031-uvc-crashrmmod-v1-1-059fe593b1e6@chromium.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 a96f6ca0889f..af6aec27083c 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 +1329,28 @@ 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);
> +
> +	if (!ret)
> +		dev->gpio_unit->gpio.inited = true;

You could simply assign !ret to it as it's called once from probe.

> +
> +	return ret;
> +}
> +
> +static void uvc_gpio_cleanup(struct uvc_device *dev)
> +{
> +	if (!dev->gpio_unit || !dev->gpio_unit->gpio.inited)
> +		return;
> +
> +	free_irq(dev->gpio_unit->gpio.irq, dev);
>  }
>  
>  /* ------------------------------------------------------------------------
> @@ -1880,6 +1893,7 @@ static void uvc_delete(struct kref *kref)
>  	struct uvc_device *dev = container_of(kref, struct uvc_device, ref);
>  	struct list_head *p, *n;
>  
> +	uvc_gpio_cleanup(dev);
>  	uvc_status_cleanup(dev);
>  	uvc_ctrl_cleanup_device(dev);
>  
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 07f9921d83f2..376cd670539b 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 inited;

I'd call this "initialised".

>  		} gpio;
>  	};
>  
> 

-- 
Regards,

Sakari Ailus

Re: [PATCH v2] media: uvcvideo: Fix crash during unbind if gpio unit is in use

[Sakari Ailus]

On Tue, Nov 05, 2024 at 10:53:59AM +0000, Ricardo Ribalda wrote:
> @@ -1329,15 +1329,28 @@ 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);
> +
> +	if (!ret)
> +		dev->gpio_unit->gpio.inited = true;

I missed:

		unit->gpio...;

Or remove unit variable altogether, it's not really needed.

-- 
Sakari Ailus

Re: [PATCH v2] media: uvcvideo: Fix crash during unbind if gpio unit is in use

[Laurent Pinchart]

Hi Ricardo,

Thank you for the patch.

On Tue, Nov 05, 2024 at 10:53:59AM +0000, Ricardo Ribalda wrote:
> 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.

The commit message should explain why you're switching away from
devm_request_threaded_irq().

> 
> 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@vger.kernel.org
> Fixes: 2886477ff987 ("media: uvcvideo: Implement UVC_EXT_GPIO_UNIT")
> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
> Changes in v2: Thanks to Laurent.
> - The main structure is not allocated with devres so there is a small
>   period of time where we can get an irq with the structure free. Do not
>   use devres for the IRQ.
> - Link to v1: https://lore.kernel.org/r/20241031-uvc-crashrmmod-v1-1-059fe593b1e6@chromium.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 a96f6ca0889f..af6aec27083c 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 +1329,28 @@ 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);
> +
> +	if (!ret)
> +		dev->gpio_unit->gpio.inited = true;

		unit->gpio.inited = true;

> +
> +	return ret;
> +}
> +
> +static void uvc_gpio_cleanup(struct uvc_device *dev)
> +{
> +	if (!dev->gpio_unit || !dev->gpio_unit->gpio.inited)
> +		return;
> +
> +	free_irq(dev->gpio_unit->gpio.irq, dev);
>  }
>  
>  /* ------------------------------------------------------------------------
> @@ -1880,6 +1893,7 @@ static void uvc_delete(struct kref *kref)
>  	struct uvc_device *dev = container_of(kref, struct uvc_device, ref);
>  	struct list_head *p, *n;
>  
> +	uvc_gpio_cleanup(dev);

This belongs to uvc_unregister_video(), or you'll have a race between
the release of the GPIO happening after .disconnect() returns, and
uvc_gpio_event() calling gpiod_get_value_cansleep().

I understand the desire to get such a fix merged quickly, but taking
time to think about race conditions instead of speeding up to get a
patch out of the door would be better. The alternative where I have to
flag race conditions multiple times during review is slower, and is more
work for everybody.

>  	uvc_status_cleanup(dev);
>  	uvc_ctrl_cleanup_device(dev);
>  
> diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> index 07f9921d83f2..376cd670539b 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 inited;

As Sakari, I also prefer "initialized". Another option to save a few
bytes of memory here is to set irq to -1 when request_threaded_irq()
fails and test that in uvc_gpio_cleanup().

>  		} gpio;
>  	};
>  
> 
> ---
> base-commit: c7ccf3683ac9746b263b0502255f5ce47f64fe0a
> change-id: 20241031-uvc-crashrmmod-666de3fc9141

-- 
Regards,

Laurent Pinchart