drm/i915: Avoid null dereference if mst_port is unset.

I'm not sure if this is really the case and I don't believe this is the real fix for the bug mentioned here, but since I don't see a reliable path when mst_port is set and when mode_valid is requested I believe it is worth to have this protection here. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102022 Cc: Elizabeth <[email protected]> Cc: Stefan Assmann <[email protected]> Cc: Dhinakaran Pandiyan <[email protected]> Signed-off-by: Rodrigo Vivi <[email protected]> Reviewed-by: Chris Wilson <[email protected]> Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
maraz · Aug 10, 2017 · 06bfe5b · 06bfe5b
1 parent 28b6cb0
commit 06bfe5b
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -370,6 +370,9 @@ intel_dp_mst_mode_valid(struct drm_connector *connector,
 	int bpp = 24; /* MST uses fixed bpp */
 	int max_rate, mode_rate, max_lanes, max_link_clock;
 
+	if (!intel_dp)
+		return MODE_ERROR;
+
 	max_link_clock = intel_dp_max_link_rate(intel_dp);
 	max_lanes = intel_dp_max_lane_count(intel_dp);