Re: [PATCH] drm/vc4: fix krealloc() memory leak

[Maíra Canal <mcanal@igalia.com>]

Hi Alexander,

On 28/05/26 15:54, Alexander A. Klimov wrote:
> 
> 
> On 5/28/26 20:17, Maíra Canal wrote:
>> Hi Alexander,
>>
>> LGTM, but a small styling nit:
>>
>> On 26/05/26 15:41, Alexander A. Klimov wrote:
>>> Don't just overwrite the original pointer passed to krealloc()
>>> with its return value without checking latter:
>>>
>>>      MEM = krealloc(MEM, SZ, GFP);
>>>
>>> If krealloc() returns NULL, that erases the pointer
>>> to the still allocated memory, hence leaks this memory.
>>> Instead, use a temporary variable, check it's not NULL
>>> and only then assign it to the original pointer:
>>>
>>>      TMP = krealloc(MEM, SZ, GFP);
>>>      if (!TMP) return;
>>>      MEM = TMP;
>>>
>>> Fixes: 6d45c81d229d ("drm/vc4: Add support for branching in shader 
>>> validation.")
>>> Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
>>> ---
>>>   drivers/gpu/drm/vc4/vc4_validate_shaders.c | 12 ++++++------
>>>   1 file changed, 6 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/vc4/vc4_validate_shaders.c b/drivers/ 
>>> gpu/drm/vc4/vc4_validate_shaders.c
>>> index d48cf76983c0..af48758592f9 100644
>>> --- a/drivers/gpu/drm/vc4/vc4_validate_shaders.c
>>> +++ b/drivers/gpu/drm/vc4/vc4_validate_shaders.c
>>> @@ -291,14 +291,14 @@ static bool 
>>> require_uniform_address_uniform(struct vc4_validated_shader_info *va
>>>       uint32_t o = validated_shader->num_uniform_addr_offsets;
>>>       uint32_t num_uniforms = validated_shader->uniforms_size / 4;
>>
>> Declare the variable here.
> 
> Strange...
> It comes already directly after num_uniforms, doesn't it?

Yeah, it does. However, usually, we declare the variables and then we
proceed to the functions. Check, for example, the function
record_texture_sample() in vc4.

Best regards,
- Maíra

> At least when I apply my patch to Linus' master.