linux-kernel - Re: [PATCH 2/2] drm/amd/display: Fix null pointer dereference in error message

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Message-ID: <76906487-8d4a-4ee9-ad28-dcef3694ed00@amd.com>
Date:   Wed, 27 Sep 2023 13:44:14 -0400
From:   Harry Wentland <harry.wentland@....com>
To:     Christian König <christian.koenig@....com>,
        Cong Liu <liucong2@...inos.cn>, Leo Li <sunpeng.li@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Aurabindo Pillai <aurabindo.pillai@....com>,
        Tom Chung <chiahsuan.chung@....com>
Cc:     dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drm/amd/display: Fix null pointer dereference in
 error message



On 2023-09-27 10:07, Harry Wentland wrote:
> 
> 
> On 2023-09-27 01:23, Christian König wrote:
>> Am 26.09.23 um 15:09 schrieb Harry Wentland:
>>>
>>> On 2023-09-26 01:56, Cong Liu wrote:
>>>> This patch fixes a null pointer dereference in the error message that is
>>>> printed when the Display Core (DC) fails to initialize. The original
>>>> message includes the DC version number, which is undefined if the DC is
>>>> not initialized.
>>>>
>>>> Fixes: 9788d087caff ("drm/amd/display: improve the message printed when loading DC")
>>>> Signed-off-by: Cong Liu <liucong2@...inos.cn>
>>>> ---
>>>>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +--
>>>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>> index 8e98dda1e084..bf52a909f558 100644
>>>> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
>>>> @@ -1703,8 +1703,7 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
>>>>           DRM_INFO("Display Core v%s initialized on %s\n", DC_VER,
>>>>                dce_version_to_string(adev->dm.dc->ctx->dce_version));
>>>>       } else {
>>>> -        DRM_INFO("Display Core v%s failed to initialize on %s\n", DC_VER,
>>>> -             dce_version_to_string(adev->dm.dc->ctx->dce_version));
>>>> +        DRM_INFO("Display Core failed to initialize with v%s!\n", DC_VER);
>>> There is value in printing the version number. Let's not remove it.
>>>
>>> Instead you can probably fix it by doing a NULL check on adev->dm.dc->ctx.
>>
>> But as far as I understand it adev->dm.dc->ctx will always be NULL in this case.
>>
> 
> Thanks, Christian. We're in the else of the NULL check for
> adev-dm.dc, so obviously we can't get the version. Silly me.
> 
> Your patch is
> Reviewed-by: Harry Wentland <harry.wentland@....com>
> 

Patch is merged.

Harry

> Harry
> 
>> Regards,
>> Christian.
>>
>>>
>>> Harry
>>>
>>>>           goto error;
>>>>       }
>>>>   
>>
>