[alsa-devel] [PATCH v2] ASoC: cht_bsw_rt5645: Fix writing to string literal

[Pierre-Louis Bossart]

On 3/3/16 5:32 AM, Vinod Koul wrote:
> On Fri, Feb 26, 2016 at 11:12:10AM +0900, Mark Brown wrote:
>> On Tue, Feb 23, 2016 at 09:50:20AM +0100, Carlo Caione wrote:
>>> From: Carlo Caione <carlo at endlessm.com>
>>>
>>> We cannot use strcpy() to write to a const char * location. This is
>>> causing a 'BUG: unable to handle kernel paging request' error at boot
>>> when using the cht-bsw-rt5645 driver.
>>>
>>> With this patch we also fix a wrong indexing in the driver where the
>>> codec_name of the wrong dai_link is being overwritten.
>>
>> So how was the original code tested then...?
>
> I know systems using this are shipping so surprised to see this.
>
> Carlo cna you please tell me the configuration where it is seen.
>
> Also would be worth mentioning here that Pierre is working on a super fix
> for this which involves removing this code and getting the right IDs from
> BIOS, so we wont need this code.

I am actually using the same code to find out which DAI fields need to 
be replaced instead of hard-codec indices so the loop part is a good thing.
There is still a need to copy a string, be it a constant to generated 
from the HID, into the codec_name field. I am not clear why strcpy() 
works on all my systems and why kstrdup() is required. Is the kernel 
issue really due to this string handling or to the bad index?