Re: [PATCH 2/3] [RFC] drm/i915/gvt: Fix opregion_header->signature size

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 24 Mar 2025, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> On Mon, 24 Mar 2025, Nicolas Chauvet <kwizart@gmail.com> wrote:
>> Enlarge the signature field to accept the string termination.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: 93615d59912 ("Revert drm/i915/gvt: Fix out-of-bounds buffer write into opregion->signature[]")
>> Signed-off-by: Nicolas Chauvet <kwizart@gmail.com>
>
> Nope, can't do that. The packed struct is used for parsing data in
> memory.

Okay, so I mixed this up with display/intel_opregion.c. So it's not used
for parsing here... but it's used for generating the data in memory, and
we can't change the layout or contents.

Regardless, we can't do either patch 2 or patch 3.

BR,
Jani.


>
> BR,
> Jani.
>
>
>> ---
>>  drivers/gpu/drm/i915/gvt/opregion.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gvt/opregion.c b/drivers/gpu/drm/i915/gvt/opregion.c
>> index 9a8ead6039e2..0f11cd6ba383 100644
>> --- a/drivers/gpu/drm/i915/gvt/opregion.c
>> +++ b/drivers/gpu/drm/i915/gvt/opregion.c
>> @@ -43,7 +43,7 @@
>>  #define DEVICE_TYPE_EFP4   0x10
>>  
>>  struct opregion_header {
>> -	u8 signature[16];
>> +	u8 signature[32];
>>  	u32 size;
>>  	u32 opregion_ver;
>>  	u8 bios_ver[32];

-- 
Jani Nikula, Intel