On Wed, Jul 29, 2020 at 5:00 PM Cengiz Can <cengiz@xxxxxxxxxx> wrote:
>
> `find_gmin_subdev` function that returns a pointer to `struct
> gmin_subdev` can return NULL.
>
> In `gmin_v2p8_ctrl` there's a call to this function but the possibility
> of a NULL was not checked before its being dereferenced. ie:
>
> ```
> /* Acquired here --------v */
> struct gmin_subdev *gs = find_gmin_subdev(subdev);
> int ret;
> int value;
>
> /* v------Dereferenced here */
> if (gs->v2p8_gpio >= 0) {
> pr_info("atomisp_gmin_platform: 2.8v power on GPIO %d\n",
> gs->v2p8_gpio);
> ret = gpio_request(gs->v2p8_gpio, "camera_v2p8");
> if (!ret)
> ret = gpio_direction_output(gs->v2p8_gpio, 0);
> if (ret)
> pr_err("V2P8 GPIO initialization failed\n");
> }
> ```
>
> I have moved the NULL check before deref point.
"Move the NULL check..."
See Submitting Patches documentation how to avoid "This patch", "I", "we", etc.
> diff --git a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
> index 0df46a1af5f0..8e9c5016f299 100644
> --- a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
> +++ b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
> @@ -871,6 +871,11 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev, int on)
> int ret;
> int value;
>
> + if (!gs) {
> + pr_err("Unable to find gmin subdevice\n");
> + return -EINVAL;
And here is a change of semantics...
> + }
...
> - if (!gs || gs->v2p8_on == on)
> + if (gs->v2p8_on == on)
> return 0;
...compared to above.
--
With Best Regards,
Andy Shevchenko
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