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SubjectRe: [PATCH v6] staging: atomisp: move null check to earlier point
Hello Andy,

Can I get some feedback on v6 please?

I hope it suits your standards this time.

Thank you

On August 2, 2020 01:02:22 Cengiz Can <cengiz@kernel.wtf> wrote:

> `find_gmin_subdev()` 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,
> i.e.:
>
> /* Acquired here --------v */
> struct gmin_subdev *gs = find_gmin_subdev(subdev);
>
> /* v------Dereferenced here */
> if (gs->v2p8_gpio >= 0) {
> ...
> }
>
> With this change we're null checking `find_gmin_subdev()` result
> and we return an error if that's the case. We also WARN()
> for the sake of debugging.
>
> Signed-off-by: Cengiz Can <cengiz@kernel.wtf>
> Reported-by: Coverity Static Analyzer CID 1465536
> Suggested-by: Mauro Carvalho Chehab <mchehab@kernel.org>
> ---
>
> Please do note that this change introduces a new return value to
> `gmin_v2p8_ctrl()`.
>
> [NEW] - raise a WARN and return -ENODEV if there are no subdevices.
> - return result of `gpio_request` or `gpio_direction_output`.
> - return 0 if GPIO is ON.
> - return results of `regulator_enable` or `regulator_disable`.
> - according to PMIC type, return result of `axp_regulator_set`
> or `gmin_i2c_write`.
> - return -EINVAL if unknown PMIC type.
>
> Patch Changelog:
> v4: Fix minor typo in commit message
> v5: Remove typo from email subject
> v6: Remove duplicate Signed-off-by tag
>
> drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
> b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
> index 0df46a1af5f0..1ad0246764a6 100644
> --- a/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
> +++ b/drivers/staging/media/atomisp/pci/atomisp_gmin_platform.c
> @@ -871,6 +871,9 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev,
> int on)
> int ret;
> int value;
>
> + if (WARN_ON(!gs))
> + return -ENODEV;
> +
> if (gs->v2p8_gpio >= 0) {
> pr_info("atomisp_gmin_platform: 2.8v power on GPIO %d\n",
> gs->v2p8_gpio);
> @@ -881,7 +884,7 @@ static int gmin_v2p8_ctrl(struct v4l2_subdev *subdev,
> int on)
> pr_err("V2P8 GPIO initialization failed\n");
> }
>
> - if (!gs || gs->v2p8_on == on)
> + if (gs->v2p8_on == on)
> return 0;
> gs->v2p8_on = on;
>
> --
> 2.27.0



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