diff --git a/services/surfaceflinger/ExSurfaceFlinger/ExHWComposer.cpp b/services/surfaceflinger/ExSurfaceFlinger/ExHWComposer.cpp
index a9934051e..92cc1a784 100644
--- a/services/surfaceflinger/ExSurfaceFlinger/ExHWComposer.cpp
+++ b/services/surfaceflinger/ExSurfaceFlinger/ExHWComposer.cpp
@@ -82,6 +82,9 @@ uint32_t ExHWComposer::getS3DFlag(int disp) const {
         return 0;
     }
 
+    if (!mHwc || uint32_t(disp) >= MAX_HWC_DISPLAYS || !mAllocatedDisplayIDs.hasBit(disp))
+        return 0;
+
     const DisplayData& disp_data(mDisplayData[disp]);
 
     for (size_t i=0 ; i<disp_data.list->numHwLayers-1; i++) {