[PATCH] drm/amd/display: check plane state before validating fbc

[S, Shirish]

From: Shirish S <shirish.s at amd.com>

While validation fbc, array_mode of the pipe is accessed without checking plane_state exists for it.
Causing to null pointer dereferencing followed by reboot when a crtc associated with external display(not
connected) is page flipped.

This patch adds a check for plane_state before using it to validate fbc.

Signed-off-by: Shirish S <shirish.s at amd.com>
Reviewed-by: Roman Li <Roman.Li at amd.com>
---
 drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
index ee3b944..a6cd63a 100644
--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
@@ -1724,6 +1724,10 @@ static enum dc_status validate_fbc(struct dc *dc,
 	if (pipe_ctx->stream->sink->link->psr_enabled)
 		return DC_ERROR_UNEXPECTED;
 
+	/* Nothing to compress */
+	if (!pipe_ctx->plane_state)
+		return DC_ERROR_UNEXPECTED;
+
 	/* Only for non-linear tiling */
 	if (pipe_ctx->plane_state->tiling_info.gfx8.array_mode == DC_ARRAY_LINEAR_GENERAL)
 		return DC_ERROR_UNEXPECTED;
--
2.7.4