drm/amd/display: check plane state before validating fbc

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@amd.com>
Reviewed-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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 be14a26..c3de7f3 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
+++ b/drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c
@@ -1774,6 +1774,10 @@ 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;