linux-kernel - Re: [PATCH] power: supply: da9150-fg: remove VLA usage

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Date:   Fri, 9 Mar 2018 11:55:40 -0600
From:   "Gustavo A. R. Silva" <garsilva@...eddedor.com>
To:     Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Support Opensource <Support.Opensource@...semi.com>,
        Sebastian Reichel <sre@...nel.org>
Cc:     "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH] power: supply: da9150-fg: remove VLA usage



On 03/09/2018 05:36 AM, Adam Thomson wrote:
> On 09 March 2018 04:58, Gustavo A. R. Silva wrote:
> 
>> In preparation to enabling -Wvla, remove VLA usage and replace it
>> with fixed-length arrays.
>>
>> It seems that the length of array 'buf' will not exceed
>> DA9150_QIF_SHORT_SIZE bytes (2 bytes). But a fixed length
>> of DA9150_QIF_BYTE_SIZE bytes (8 bytes) was chosen in case
>> this change in the future.
>>
>> Fixed as part of the directive to remove all VLAs from
>> the kernel: https://lkml.org/lkml/2018/3/7/621
>>
>> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
>> ---
>>   drivers/power/supply/da9150-fg.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/power/supply/da9150-fg.c b/drivers/power/supply/da9150-fg.c
>> index 8b8ce97..96893be 100644
>> --- a/drivers/power/supply/da9150-fg.c
>> +++ b/drivers/power/supply/da9150-fg.c
>> @@ -92,7 +92,7 @@ struct da9150_fg {
>>   static u32 da9150_fg_read_attr(struct da9150_fg *fg, u8 code, u8 size)
>>
>>   {
>> -	u8 buf[size];
>> +	u8 buf[DA9150_QIF_BYTE_SIZE];
> 
> You can use DA9150_QIF_LONG_SIZE as that's the biggest size of an attribute
> which can be accessed. This will also save a little space.
> 

I got it. I'll send v2 shortly.

Thanks for the feedback, Adam.
--
Gustavo