Re: [PATCH] iio: adc: Fix a null pointer dereference in pac1934_acpi_parse_channel_config

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 1 Sep 2025 14:45:11 +0800
Charles Han <hanchunchao@inspur.com> wrote:

> Add check for the return value of devm_kmemdup()
> to prevent potential null pointer dereference.
> 
> Fixes: 0fb528c8255b ("iio: adc: adding support for PAC193x")
> Signed-off-by: Charles Han <hanchunchao@inspur.com>
Good catch, but not that simple. This just leaked an ACPI resource that was
held over the loop this is in. See the ACPI_FREE() that follows it.

Jonathan

> ---
>  drivers/iio/adc/pac1934.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/iio/adc/pac1934.c b/drivers/iio/adc/pac1934.c
> index 2e442e46f679..95c9d14b5529 100644
> --- a/drivers/iio/adc/pac1934.c
> +++ b/drivers/iio/adc/pac1934.c
> @@ -1108,6 +1108,9 @@ static int pac1934_acpi_parse_channel_config(struct i2c_client *client,
>  			devm_kmemdup(dev, rez->package.elements[i].string.pointer,
>  				     (size_t)rez->package.elements[i].string.length + 1,
>  				     GFP_KERNEL);
> +		if (!info->labels[idx])
> +			return -ENOMEM;
> +
>  		info->labels[idx][rez->package.elements[i].string.length] = '\0';
>  		info->shunts[idx] = rez->package.elements[i + 1].integer.value * 1000;
>  		info->active_channels[idx] = (info->shunts[idx] != 0);