[PATCH] amdgpu/dc: Avoid dereferencing NULL pointer

[Harry Wentland]

On 2017-10-27 02:34 PM, Drew Davenport wrote:
> crtc is dereferenced from within drm_atomic_get_new_crtc_state, so
> check for NULL before initializing new_crtc_state.
> 
> Signed-off-by: Drew Davenport <ddavenport at chromium.org>

Reviewed-by: Harry Wentland <harry.wentland at amd.com>

Harry

> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 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 d0ee1b3b8b5c..5a440fadbe18 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -3874,8 +3874,7 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
>  	/* update planes when needed */
>  	for_each_oldnew_plane_in_state(state, plane, old_plane_state, new_plane_state, i) {
>  		struct drm_crtc *crtc = new_plane_state->crtc;
> -		struct drm_crtc_state *new_crtc_state =
> -				drm_atomic_get_new_crtc_state(state, crtc);
> +		struct drm_crtc_state *new_crtc_state;
>  		struct drm_framebuffer *fb = new_plane_state->fb;
>  		bool pflip_needed;
>  		struct dm_plane_state *dm_new_plane_state = to_dm_plane_state(new_plane_state);
> @@ -3885,7 +3884,11 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
>  			continue;
>  		}
>  
> -		if (!fb || !crtc || pcrtc != crtc || !new_crtc_state->active)
> +		if (!fb || !crtc || pcrtc != crtc)
> +			continue;
> +
> +		new_crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
> +		if (!new_crtc_state->active)
>  			continue;
>  
>  		pflip_needed = !state->allow_modeset;
>