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

[Harry Wentland <harry.wentland@amd.com>]

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@kylinos.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.

Harry

>  		goto error;
>  	}
>