Re: [RFT PATCH 0/3] Fix kfree() of const memory on setting driver_override

[Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>]

On 22/02/2022 14:51, Rasmus Villemoes wrote:
> On 22/02/2022 14.27, Krzysztof Kozlowski wrote:
>> Hi,
>>
>> Drivers still seem to use driver_override incorrectly. Perhaps my old
>> patch makes sense now?
>> https://lore.kernel.org/all/1550484960-2392-3-git-send-email-krzk@kernel.org/
>>
>> Not tested - please review and test (e.g. by writing to dirver_override
>> sysfs entry with KASAN enabled).
> 
> Perhaps it would make sense to update the core code to release using
> kfree_const(), allowing drivers to set the initial value with
> kstrdup_const(). Drivers that currently use kstrdup() or kasprintf()
> will continue to work [but if they kstrdup() a string literal they could
> be changed to use kstrdup_const].

The core here means several buses, so the change would not be that
small. However I don't see the reason why "driver_override" is special
and should be freed with kfree_const() while most of other places don't
use it.

The driver_override field definition is here obvious: "char *", so any
assignments of "const char *" are logically wrong (although GCC does not
warn of this literal string const discarding). Adding kfree_const() is
hiding the problem - someone did not read the definition of assigned field.

Best regards,
Krzysztof