linux-kernel - Re: [PATCH 2/3] staging: r8188eu: refactor rtw

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Date:   Sun, 20 Feb 2022 17:30:08 +0100
From:   Michael Straube <straube.linux@...il.com>
To:     Pavel Skripkin <paskripkin@...il.com>, gregkh@...uxfoundation.org
Cc:     Larry.Finger@...inger.net, phil@...lpotter.co.uk,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] staging: r8188eu: refactor rtw_ch2freq()

On 2/20/22 17:20, Pavel Skripkin wrote:
> Hi Michael,
> 
> On 2/20/22 18:48, Michael Straube wrote:
>> -static int ch_freq_map_num = ARRAY_SIZE(ch_freq_map);
>> -
>>   u32 rtw_ch2freq(u32 channel)
>>   {
>> -    u8    i;
>> -    u32    freq = 0;
>> -
>> -    for (i = 0; i < ch_freq_map_num; i++) {
>> -        if (channel == ch_freq_map[i].channel) {
>> -            freq = ch_freq_map[i].frequency;
>> -                break;
>> -        }
>> -    }
>> -    if (i == ch_freq_map_num)
>> -        freq = 2412;
>> -
>> -    return freq;
>> +    return ch_freq_map[channel - 1];
>>   }
> 
> What if channel has wrong value? The old code returned some default 
> value, but with new one we will hit OOB.
> 

Hi Pavel,

thanks for reviewing. Yeah, I thought about adding a check for channel
value between 1 and 14. But I did not add it because I think if this
function will ever be called with channel < 1 or channel > 14, then the
calling code must be wrong.

Would be nice to see what others think about this.

Thanks,
Michael