linux-kernel - Re: [PATCH v3 1/2] mwifiex: Use a define for firmware version string length

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Date:   Wed, 3 Nov 2021 21:01:49 +0100
From:   Jonas Dreßler <verdre@...d.nl>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Amitkumar Karwar <amitkarwar@...il.com>,
        Ganapathi Bhat <ganapathi017@...il.com>,
        Xinming Hu <huxinming820@...il.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Tsuchiya Yuto <kitakar@...il.com>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Maximilian Luz <luzmaximilian@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Pali Rohár <pali@...nel.org>
Subject: Re: [PATCH v3 1/2] mwifiex: Use a define for firmware version string
 length

On 11/3/21 18:28, Brian Norris wrote:
> On Wed, Nov 03, 2021 at 06:10:54PM +0100, Jonas Dreßler wrote:
>> Since the version string we get from the firmware is always 128
>> characters long, use a define for this size instead of having the number
>> 128 copied all over the place.
>>
>> Signed-off-by: Jonas Dreßler <verdre@...d.nl>
> 
> Thanks for this patch. For the series:
> 
> Reviewed-by: Brian Norris <briannorris@...omium.org>
> 
>> ---
>>   drivers/net/wireless/marvell/mwifiex/fw.h          | 4 +++-
>>   drivers/net/wireless/marvell/mwifiex/main.h        | 2 +-
>>   drivers/net/wireless/marvell/mwifiex/sta_cmdresp.c | 5 +++--
>>   3 files changed, 7 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/net/wireless/marvell/mwifiex/fw.h b/drivers/net/wireless/marvell/mwifiex/fw.h
>> index 2ff23ab259ab..63c25c69ed2b 100644
>> --- a/drivers/net/wireless/marvell/mwifiex/fw.h
>> +++ b/drivers/net/wireless/marvell/mwifiex/fw.h
>> @@ -2071,9 +2071,11 @@ struct mwifiex_ie_types_robust_coex {
>>   	__le32 mode;
>>   } __packed;
>>   
>> +#define MWIFIEX_VERSION_STR_LENGTH  128
>> +
>>   struct host_cmd_ds_version_ext {
>>   	u8 version_str_sel;
>> -	char version_str[128];
>> +	char version_str[MWIFIEX_VERSION_STR_LENGTH];
>>   } __packed;
>>   
>>   struct host_cmd_ds_mgmt_frame_reg {
>> diff --git a/drivers/net/wireless/marvell/mwifiex/main.h b/drivers/net/wireless/marvell/mwifiex/main.h
>> index 90012cbcfd15..65609ea2327e 100644
>> --- a/drivers/net/wireless/marvell/mwifiex/main.h
>> +++ b/drivers/net/wireless/marvell/mwifiex/main.h
>> @@ -646,7 +646,7 @@ struct mwifiex_private {
>>   	struct wireless_dev wdev;
>>   	struct mwifiex_chan_freq_power cfp;
>>   	u32 versionstrsel;
>> -	char version_str[128];
>> +	char version_str[MWIFIEX_VERSION_STR_LENGTH];
>>   #ifdef CONFIG_DEBUG_FS
>>   	struct dentry *dfs_dev_dir;
>>   #endif
>> diff --git a/drivers/net/wireless/marvell/mwifiex/sta_cmdresp.c b/drivers/net/wireless/marvell/mwifiex/sta_cmdresp.c
>> index 6b5d35d9e69f..20b69a37f9e1 100644
>> --- a/drivers/net/wireless/marvell/mwifiex/sta_cmdresp.c
>> +++ b/drivers/net/wireless/marvell/mwifiex/sta_cmdresp.c
>> @@ -711,8 +711,9 @@ static int mwifiex_ret_ver_ext(struct mwifiex_private *priv,
>>   	if (version_ext) {
>>   		version_ext->version_str_sel = ver_ext->version_str_sel;
>>   		memcpy(version_ext->version_str, ver_ext->version_str,
>> -		       sizeof(char) * 128);
>> -		memcpy(priv->version_str, ver_ext->version_str, 128);
>> +		       MWIFIEX_VERSION_STR_LENGTH);
>> +		memcpy(priv->version_str, ver_ext->version_str,
>> +		       MWIFIEX_VERSION_STR_LENGTH);
> 
> Not related to your patch, but this highlights that nobody is ensuring
> this string is 0-terminated, and various other places (notably, *not*
> your patch 2!) assume that it is.
> 
> We should either fix those to use an snprintf()/length-restricted
> variant, or else just force:
> 
> 		priv->version_str[MWIFIEX_VERSION_STR_LENGTH - 1] = '\0';
> 
> here.

Indeed, right now we just trust the firmware to make sure that's the case.

Let me add another patch appending the '\0' to priv->version_str...

> 
> But that's a separate issue/patch. I can cook one on top of your series
> when it gets merged if you don't want to.
> 
> Brian
> 
>>   	}
>>   	return 0;
>>   }
>> -- 
>> 2.33.1
>>