linux-kernel - Re: [PATCH v2] ASoC: Intel: Skylake: prevent memory leak in snd_skl_parse

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Date:   Fri, 27 Sep 2019 08:14:00 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Navid Emamdoost <navid.emamdoost@...il.com>
Cc:     emamd001@....edu, smccaman@....edu, kjlu@....edu,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        Liam Girdwood <liam.r.girdwood@...ux.intel.com>,
        Jie Yang <yang.jie@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, Enrico Weigelt <info@...ux.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ASoC: Intel: Skylake: prevent memory leak in
 snd_skl_parse_uuids

On 9/26/19 9:55 PM, Navid Emamdoost wrote:
> On Wed, Sep 25, 2019 at 12:05:28PM -0500, Pierre-Louis Bossart wrote:
>> On 9/25/19 11:19 AM, Navid Emamdoost wrote:
>>> In snd_skl_parse_uuids if allocation for module->instance_id fails, the
>>> allocated memory for module shoulde be released. I changes the
>>> allocation for module to use devm_kzalloc to be resource_managed
>>> allocation and avoid the release in error path.
>>
>> if you use devm_, don't you need to fix the error path as well then, I see a
>> kfree(uuid) in skl_freeup_uuid_list().
>>
>> I am not very familiar with this code but the error seems to be that the
>> list_add_tail() is called after the module->instance_id is allocated, so
>> there is a risk that the module allocated earlier is not freed (since it's
>> not yet added to the list). Freeing the module as done in patch 1 works,
>> using devm_ without fixing the error path does not seem correct to me.
>>
> Thanks for the feedback, then it's your call if you can accept patch 1 as
> fix.

Cezary, it's really your call.

> Navid.
>>>
>>> Signed-off-by: Navid Emamdoost <navid.emamdoost@...il.com>
>>> ---
>>> Changes in v2:
>>> 	- Changed the allocation for module from kzalloc to devm_kzalloc
>>> ---
>>>    sound/soc/intel/skylake/skl-sst-utils.c | 2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/sound/soc/intel/skylake/skl-sst-utils.c b/sound/soc/intel/skylake/skl-sst-utils.c
>>> index d43cbf4a71ef..ac37f04b0eea 100644
>>> --- a/sound/soc/intel/skylake/skl-sst-utils.c
>>> +++ b/sound/soc/intel/skylake/skl-sst-utils.c
>>> @@ -284,7 +284,7 @@ int snd_skl_parse_uuids(struct sst_dsp *ctx, const struct firmware *fw,
>>>    	 */
>>>    	for (i = 0; i < num_entry; i++, mod_entry++) {
>>> -		module = kzalloc(sizeof(*module), GFP_KERNEL);
>>> +		module = devm_kzalloc(ctx->dev, sizeof(*module), GFP_KERNEL);
>>>    		if (!module) {
>>>    			ret = -ENOMEM;
>>>    			goto free_uuid_list;
>>>
>>