2022-12-07 15:19:30

by Aleksandr Burakov

Subject: [PATCH] media: v4l2-flash: fix NULL dereference in v4l2_flash_s_ctrl()

The NULL check added for fled_cdev before dereference.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Aleksandr Burakov <[email protected]>
Fixes: 42bd6f59ae90 ("media: Add registration helpers for V4L2 flash sub-devices")
---
drivers/media/v4l2-core/v4l2-flash-led-class.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-flash-led-class.c b/drivers/media/v4l2-core/v4l2-flash-led-class.c
index 355595a0fefa..36cc46e80eea 100644
--- a/drivers/media/v4l2-core/v4l2-flash-led-class.c
+++ b/drivers/media/v4l2-core/v4l2-flash-led-class.c
@@ -291,12 +291,16 @@ static int v4l2_flash_s_ctrl(struct v4l2_ctrl *c)
* No conversion is needed as LED Flash class also uses
* microseconds for flash timeout units.
*/
+ if (!fled_cdev)
+ return -EINVAL;
return led_set_flash_timeout(fled_cdev, c->val);
case V4L2_CID_FLASH_INTENSITY:
/*
* No conversion is needed as LED Flash class also uses
* microamperes for flash intensity units.
*/
+ if (!fled_cdev)
+ return -EINVAL;
return led_set_flash_brightness(fled_cdev, c->val);
}

--
2.25.1

2023-01-16 21:17:54

by Sakari Ailus

Subject: Re: [PATCH] media: v4l2-flash: fix NULL dereference in v4l2_flash_s_ctrl()

Hi Alexandr,

On Wed, Dec 07, 2022 at 05:18:07PM +0300, Aleksandr Burakov wrote:
> The NULL check added for fled_cdev before dereference.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Signed-off-by: Aleksandr Burakov <[email protected]>
> Fixes: 42bd6f59ae90 ("media: Add registration helpers for V4L2 flash sub-devices")
> ---
> drivers/media/v4l2-core/v4l2-flash-led-class.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-flash-led-class.c b/drivers/media/v4l2-core/v4l2-flash-led-class.c
> index 355595a0fefa..36cc46e80eea 100644
> --- a/drivers/media/v4l2-core/v4l2-flash-led-class.c
> +++ b/drivers/media/v4l2-core/v4l2-flash-led-class.c
> @@ -291,12 +291,16 @@ static int v4l2_flash_s_ctrl(struct v4l2_ctrl *c)
> * No conversion is needed as LED Flash class also uses
> * microseconds for flash timeout units.
> */
> + if (!fled_cdev)
> + return -EINVAL;
> return led_set_flash_timeout(fled_cdev, c->val);
> case V4L2_CID_FLASH_INTENSITY:
> /*
> * No conversion is needed as LED Flash class also uses
> * microamperes for flash intensity units.
> */
> + if (!fled_cdev)
> + return -EINVAL;
> return led_set_flash_brightness(fled_cdev, c->val);
> }
>

fled_cdev won't be NULL above, this is checked elsewhere in the V4L2 flash
LED class code. I guess the question then is whether doing such a check is
meaningful. It would require a bug elsewhere in the code to happen.

--
Kind regards,

Sakari Ailus