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From:   Jani Nikula <jani.nikula@linux.intel.com>
To:     Xia Fukun <xiafukun@huawei.com>, airlied@gmail.com,
        daniel@ffwll.ch, ville.syrjala@linux.intel.com,
        lucas.demarchi@intel.com, joonas.lahtinen@linux.intel.com
Cc:     intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, rodrigo.vivi@intel.com,
        xiafukun@huawei.com
Subject: Re: [Intel-gfx] [PATCH] drm/i915/bios: fix a memory leak in
 generate_lfp_data_ptrs
In-Reply-To: <875yf35tx1.fsf@intel.com>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
References: <20221125063428.69486-1-xiafukun@huawei.com>
 <875yf35tx1.fsf@intel.com>
Date:   Tue, 29 Nov 2022 11:50:43 +0200
Message-ID: <87fse23x8s.fsf@intel.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Fri, 25 Nov 2022, Jani Nikula <jani.nikula@linux.intel.com> wrote:
> On Fri, 25 Nov 2022, Xia Fukun <xiafukun@huawei.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@huawei.com>
>
> Reviewed-by: Jani Nikula <jani.nikula@intel.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