linux-kernel - Re: [PATCH] ASoC: SOF: Fix null pointer dereference in sof_pci

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Date:   Tue, 5 Dec 2023 17:10:57 +0800
From:   Kunwu Chan <chentao@...inos.cn>
To:     Péter Ujfalusi <peter.ujfalusi@...ux.intel.com>,
        pierre-louis.bossart@...ux.intel.com, lgirdwood@...il.com,
        yung-chuan.liao@...ux.intel.com, ranjani.sridharan@...ux.intel.com,
        daniel.baluta@....com, kai.vehmanen@...ux.intel.com,
        broonie@...nel.org, perex@...ex.cz, tiwai@...e.com,
        chao.song@...el.com
Cc:     kunwu.chan@...mail.com, sound-open-firmware@...a-project.org,
        linux-sound@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: SOF: Fix null pointer dereference in sof_pci_probe

It's my bad, i'll follow your suggestion in v2 patch:
1. remove 'Fixes: 46207ca24545' label

2. rename subject to 'ASoC: SOF: Add null pointer check to sof_pci_probe'

3. when sof_pdata->fw_filename_prefix is NULL,don't use it to dev_dbg. 
Or just use a
if (sof_pdata->fw_filename_prefix)
         dev_dbg(dev,
                 "Platform uses community key, changed fw path to %s\n",
                 sof_pdata->fw_filename_prefix);
else
	dev_dbg(dev,
                 "Platform uses community key, changed fw path to %s/%s\n",
                  sof_pdata->desc->default_fw_path[sof_pdata->ipc_type],
                  "community");

Is it okay to modify it like this?


Thanks,
Kunwu

On 2023/12/4 19:34, Péter Ujfalusi wrote:
> 
> 
> On 23/11/2023 17:54, Kunwu Chan wrote:
>> devm_kasprintf() returns a pointer to dynamically allocated memory
>> which can be NULL upon failure.
>>
>> Fixes: 46207ca24545 ("ASoC: SOF: pci: change the default firmware path when the community key is used")
>> Fixes: 25bbc0c59ee1 ("ASoC: SOF: Add path definition for external firmware libraries")
>> Signed-off-by: Kunwu Chan <chentao@...inos.cn>
> 
> This patch cannot fix both commits as at 46207ca24545 the lib path was
> not present.
> Please don't bundle unrelated fixes, it makes maintainers life harder.
> 
> As a note: if the allocation fails it is not going to cause null
> dereference as the code checks !sof_pdata->*_prefix to see if it is
> provided (override) or not (use default).
> At most it will cause the kernel to 'ignore' the path override, but if
> this allocation fails this is least of our problem ;)
> 
>> ---
>>   sound/soc/sof/sof-pci-dev.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/sound/soc/sof/sof-pci-dev.c b/sound/soc/sof/sof-pci-dev.c
>> index 64b326e3ef85..75a9bfa5bfbe 100644
>> --- a/sound/soc/sof/sof-pci-dev.c
>> +++ b/sound/soc/sof/sof-pci-dev.c
>> @@ -282,6 +282,10 @@ int sof_pci_probe(struct pci_dev *pci, const struct pci_device_id *pci_id)
>>   			devm_kasprintf(dev, GFP_KERNEL, "%s/%s",
>>   				       sof_pdata->desc->default_fw_path[sof_pdata->ipc_type],
>>   				       "community");
>> +		if (!sof_pdata->fw_filename_prefix) {
>> +			ret = -ENOMEM;	
>> +			goto out;
>> +		}
>>   
>>   		dev_dbg(dev,
>>   			"Platform uses community key, changed fw path to %s\n",
>> @@ -303,6 +307,10 @@ int sof_pci_probe(struct pci_dev *pci, const struct pci_device_id *pci_id)
>>   				devm_kasprintf(dev, GFP_KERNEL, "%s/%s",
>>   					sof_pdata->desc->default_lib_path[sof_pdata->ipc_type],
>>   					"community");
>> +			if (!sof_pdata->fw_lib_prefix) {
>> +				ret = -ENOMEM;
>> +				goto out;
>> +			}
>>   
>>   			dev_dbg(dev,
>>   				"Platform uses community key, changed fw_lib path to %s\n",
>