Re: [PATCH] ASoC: SOF: ipc4-topology: Use size_t for variable passed to kzalloc() - Pierre-Louis Bossart

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Peter Ujfalusi <peter.ujfalusi@linux.intel.com>,
	Bard Liao <yung-chuan.liao@linux.intel.com>,
	Ranjani Sridharan <ranjani.sridharan@linux.intel.com>,
	Daniel Baluta <daniel.baluta@nxp.com>,
	Kai Vehmanen <kai.vehmanen@linux.intel.com>,
	Mark Brown <broonie@kernel.org>, Jaroslav Kysela <perex@perex.cz>,
	Takashi Iwai <tiwai@suse.com>,
	Dan Carpenter <dan.carpenter@oracle.com>
Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org,
	sound-open-firmware@alsa-project.org,
	alsa-devel@alsa-project.org
Subject: Re: [PATCH] ASoC: SOF: ipc4-topology: Use size_t for variable passed to kzalloc()
Date: Thu, 1 Jun 2023 12:39:42 -0500	[thread overview]
Message-ID: <2720a80a-4496-0ba9-e545-046ed2529f7d@linux.intel.com> (raw)
In-Reply-To: <a311e4ae83406f714c9d1f7f2f857284265e581c.1685640591.git.christophe.jaillet@wanadoo.fr>

On 6/1/23 12:30, Christophe JAILLET wrote:
> struct_size() checks for overflow, but assigning its result to just a u32
> may still overflow after a successful check.
> 
> Use a size_t instead in order to be cleaner.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> Based on analysis from Dan Carpenter on another patch (see [1]).
> 
> [1]: https://lore.kernel.org/all/00e84595-e2c9-48ea-8737-18da34eaafbf@kili.mountain/

looks like there are similar cases of struct_size -> u32 conversions in
other places:

struct snd_sof_control {
    u32 size;	/* cdata size */

ipc3-topology.c:        scontrol->size = struct_size(cdata, chanv,
scontrol->num_channels);
ipc3-topology.c:        scontrol->size = struct_size(cdata, chanv,
scontrol->num_channels);
ipc4-topology.c:        scontrol->size = struct_size(control_data,
chanv, scontrol->num_channels);

not sure how much of an issue this really is though?

> ---
>  sound/soc/sof/ipc4-topology.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/soc/sof/ipc4-topology.c b/sound/soc/sof/ipc4-topology.c
> index db64e0cb8663..50faa4c88b97 100644
> --- a/sound/soc/sof/ipc4-topology.c
> +++ b/sound/soc/sof/ipc4-topology.c
> @@ -881,7 +881,7 @@ static int sof_ipc4_widget_setup_comp_process(struct snd_sof_widget *swidget)
>  	/* allocate memory for base config extension if needed */
>  	if (process->init_config == SOF_IPC4_MODULE_INIT_CONFIG_TYPE_BASE_CFG_WITH_EXT) {
>  		struct sof_ipc4_base_module_cfg_ext *base_cfg_ext;
> -		u32 ext_size = struct_size(base_cfg_ext, pin_formats,
> +		size_t ext_size = struct_size(base_cfg_ext, pin_formats,
>  						swidget->num_input_pins + swidget->num_output_pins);
>  
>  		base_cfg_ext = kzalloc(ext_size, GFP_KERNEL);