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SubjectRe: [PATCH] media: staging: greybus: Release memory obtained by kasprintf
On Thu, Sep 21, 2017 at 05:05:27PM +0530, Arvind Yadav wrote:
> Free memory region, if gb_lights_channel_config is not successful.
>

The question I have is do we free this on module unload? I don't see
that we do. I feel like we should do a free after calling
__gb_lights_led_unregister(). But that's awkward because we call
__gb_lights_led_unregister() when this function fails so it would end
up being a double free.

> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> ---
> drivers/staging/greybus/light.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
> index 3f4148c..b00d47c 100644
> --- a/drivers/staging/greybus/light.c
> +++ b/drivers/staging/greybus/light.c
> @@ -984,7 +984,7 @@ static int gb_lights_channel_config(struct gb_light *light,
>
> ret = channel_attr_groups_set(channel, cdev);
> if (ret < 0)
> - return ret;
> + goto err;
>
> gb_lights_led_operations_set(channel, cdev);
>
> @@ -994,15 +994,18 @@ static int gb_lights_channel_config(struct gb_light *light,
> * configurations.
> */
> if (!is_channel_flash(channel))
> - return ret;
> + goto err;

"ret" is zero here. This is actually a success return. It would be
cleaner to just write "return 0;". Anyway, this patch introduces a use
after free so that doesn't work.

Also it's better to choose a label name which says what the label does
so in this case it would be "goto err_free_name" or "goto err_cdev_name"
or whatever, but something to indicate that it's to do with freeing
the cdev->name. Just "err" is too ambiguous.

>
> light->has_flash = true;
>
> ret = gb_lights_channel_flash_config(channel);
> if (ret < 0)
> - return ret;
> + goto err;
>
> return ret;
^^^^^^^^^^
Here as well, change this from "return ret;" to "return 0;".

regards,
dan carpenter

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