linux-kernel - Re: [PATCH] iio: adc: Fix a null pointer dereference in pac1934_acpi_parse_channel

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Message-ID: <20250901174919.4e2c7873@jic23-huawei>
Date: Mon, 1 Sep 2025 17:49:19 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Charles Han <hanchunchao@...pur.com>
Cc: <marius.cristea@...rochip.com>, <dlechner@...libre.com>,
 <nuno.sa@...log.com>, <andy@...nel.org>, <linux-iio@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: adc: Fix a null pointer dereference in
 pac1934_acpi_parse_channel_config

On Mon, 1 Sep 2025 14:45:11 +0800
Charles Han <hanchunchao@...pur.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@...pur.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);