On Tue, Nov 05, 2024 at 02:21:38PM +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.

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

That may or may not be true, depending on whether or not userspace holds on to resources.

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

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Changes in v5:

• Revert non refcount, that belongs to a different set
• Move cleanup to a different function
• Link to v4: https://lore.kernel.org/r/20241105-uvc-crashrmmod-v4-0-410e548f097a@chromium...

Changes in v4: Thanks Laurent.

• Remove refcounted cleaup to support devres.
• Link to v3: https://lore.kernel.org/r/20241105-uvc-crashrmmod-v3-1-c0959c8906d3@chromium...

Changes in v3: Thanks Sakari.

• Rename variable to initialized.
• Other CodeStyle.
• Link to v2: https://lore.kernel.org/r/20241105-uvc-crashrmmod-v2-1-547ce6a6962e@chromium...

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...

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drivers/media/usb/uvc/uvc_driver.c | 27 ++++++++++++++++++++------- drivers/media/usb/uvc/uvcvideo.h | 1 + 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index a96f6ca0889f..aa937f07b6b5 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_cleanup(struct uvc_device *dev) +{

• if (!dev->gpio_unit || !dev->gpio_unit->gpio.initialized)

• return;
  

• free_irq(dev->gpio_unit->gpio.irq, dev);

} /* ------------------------------------------------------------------------ @@ -1982,6 +1994,7 @@ static void uvc_unregister_video(struct uvc_device *dev) if (media_devnode_is_registered(dev->mdev.devnode)) media_device_unregister(&dev->mdev); #endif

• uvc_gpio_cleanup(dev);

Have you checked in details that doing this at the *end* of uvc_unregister_video(), after lots of resources get unregistered, will not cause any issue if the IRQ occurs somewhere in the middle of this function ? It would seem much safer to free the IRQ at the *beginning* of the function, the same way that drivers should generally stop hardware activity first, and only then release resources that may be needed when handling hardware activity.

} int uvc_register_video_device(struct uvc_device *dev, 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; };

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