[Intel-gfx] [PATCH] drm/i915: Fix NULL ptr deref by checking new_crtc_state

[Stanislav Lisovskiy]

intel_atomic_get_new_crtc_state can return NULL, unless crtc state wasn't
obtained previously with intel_atomic_get_crtc_state, so we must check it
for NULLness here, just as in many other places, where we can't guarantee
that intel_atomic_get_crtc_state was called.
We are currently getting NULL ptr deref because of that, so this fix was
confirmed to help.

Fixes: 74a75dc90869 ("drm/i915/display: move plane prepare/cleanup to 
intel_atomic_plane.c")
Signed-off-by: Stanislav Lisovskiy <stanislav.lisovs...@intel.com>
---
 drivers/gpu/drm/i915/display/intel_atomic_plane.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_atomic_plane.c 
b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
index 9f670dcfe76e..4125ee07a271 100644
--- a/drivers/gpu/drm/i915/display/intel_atomic_plane.c
+++ b/drivers/gpu/drm/i915/display/intel_atomic_plane.c
@@ -1029,7 +1029,7 @@ intel_prepare_plane_fb(struct drm_plane *_plane,
        int ret;
 
        if (old_obj) {
-               const struct intel_crtc_state *crtc_state =
+               const struct intel_crtc_state *new_crtc_state =
                        intel_atomic_get_new_crtc_state(state,
                                                        
to_intel_crtc(old_plane_state->hw.crtc));
 
@@ -1044,7 +1044,7 @@ intel_prepare_plane_fb(struct drm_plane *_plane,
                 * This should only fail upon a hung GPU, in which case we
                 * can safely continue.
                 */
-               if (intel_crtc_needs_modeset(crtc_state)) {
+               if (new_crtc_state && intel_crtc_needs_modeset(new_crtc_state)) 
{
                        ret = 
i915_sw_fence_await_reservation(&state->commit_ready,
                                                              
old_obj->base.resv,
                                                              false, 0,
-- 
2.37.3