linux-kernel - Re: [Intel-gfx] [PATCH] drm/i915/bios: fix a memory leak in generate_lfp_data

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Date:   Tue, 29 Nov 2022 11:50:43 +0200
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Xia Fukun <xiafukun@...wei.com>, airlied@...il.com,
        daniel@...ll.ch, ville.syrjala@...ux.intel.com,
        lucas.demarchi@...el.com, joonas.lahtinen@...ux.intel.com
Cc:     intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, rodrigo.vivi@...el.com,
        xiafukun@...wei.com
Subject: Re: [Intel-gfx] [PATCH] drm/i915/bios: fix a memory leak in
 generate_lfp_data_ptrs

On Fri, 25 Nov 2022, Jani Nikula <jani.nikula@...ux.intel.com> wrote:
> On Fri, 25 Nov 2022, Xia Fukun <xiafukun@...wei.com> wrote:
>> When (size != 0 || ptrs->lvds_ entries != 3), the program tries to
>> free() the ptrs. However, the ptrs is not created by calling kzmalloc(),
>> but is obtained by pointer offset operation.
>> This may lead to memory leaks or undefined behavior.
>
> Yeah probably worse things will happen than just leak.
>
>>
>> Fix this by replacing the arguments of kfree() with ptrs_block.
>>
>> Fixes: a87d0a847607 ("drm/i915/bios: Generate LFP data table pointers if the VBT lacks them")
>> Signed-off-by: Xia Fukun <xiafukun@...wei.com>
>
> Reviewed-by: Jani Nikula <jani.nikula@...el.com>

And pushed to drm-intel-next, thanks for the patch.

BR,
Jani.

>
>> ---
>>  drivers/gpu/drm/i915/display/intel_bios.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
>> index 28bdb936cd1f..edbdb949b6ce 100644
>> --- a/drivers/gpu/drm/i915/display/intel_bios.c
>> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
>> @@ -414,7 +414,7 @@ static void *generate_lfp_data_ptrs(struct drm_i915_private *i915,
>>  		ptrs->lvds_entries++;
>>  
>>  	if (size != 0 || ptrs->lvds_entries != 3) {
>> -		kfree(ptrs);
>> +		kfree(ptrs_block);
>>  		return NULL;
>>  	}

-- 
Jani Nikula, Intel Open Source Graphics Center