[Intel-gfx] [PATCH] drm/i915: Avoid drm_atomic_state_put(NULL) on error paths

[Ander Conselvan de Oliveira]

The error paths in hsw_trans_edp_pipe_A_crc_wa() and
intel_prepare_reset() would potentially call drm_atomic_state_put with a
NULL state, which would lead to a NULL pointer dereference.

Found by coverity.

Fixes: 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: <drm-intel-fixes at lists.freedesktop.org> # v4.10-rc1+
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c  | 3 ++-
 drivers/gpu/drm/i915/intel_pipe_crc.c | 4 +++-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index caa2e02..b5a09bd 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3577,7 +3577,8 @@ void intel_prepare_reset(struct drm_i915_private *dev_priv)
 	return;
 
 err:
-	drm_atomic_state_put(state);
+	if (state)
+		drm_atomic_state_put(state);
 }
 
 void intel_finish_reset(struct drm_i915_private *dev_priv)
diff --git a/drivers/gpu/drm/i915/intel_pipe_crc.c b/drivers/gpu/drm/i915/intel_pipe_crc.c
index 0f1da81..f1bbf49 100644
--- a/drivers/gpu/drm/i915/intel_pipe_crc.c
+++ b/drivers/gpu/drm/i915/intel_pipe_crc.c
@@ -579,7 +579,9 @@ static void hsw_trans_edp_pipe_A_crc_wa(struct drm_i915_private *dev_priv,
 out:
 	WARN(ret, "Toggling workaround to %i returns %i\n", enable, ret);
 	drm_modeset_unlock_all(dev);
-	drm_atomic_state_put(state);
+
+	if (state)
+		drm_atomic_state_put(state);
 }
 
 static int ivb_pipe_crc_ctl_reg(struct drm_i915_private *dev_priv,
-- 
2.5.5