From 96b2096dd326ea5525e7d7cc838524854de40e4d Mon Sep 17 00:00:00 2001
From: Lee Salzman <lsalzman@mozilla.com>
Date: Mon, 21 Mar 2016 10:48:35 -0400
Subject: [PATCH] Bug 1256515 - bail out in
 CanvasRenderingContext2D::DrawWindow if snapshotting draw target fails.
 r=bas.schouten a=lizzard

MozReview-Commit-ID: LxQ3v8zqXI
---
 dom/canvas/CanvasRenderingContext2D.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/dom/canvas/CanvasRenderingContext2D.cpp b/dom/canvas/CanvasRenderingContext2D.cpp
index 99e54175118..c7fa8ef7999 100644
--- a/dom/canvas/CanvasRenderingContext2D.cpp
+++ b/dom/canvas/CanvasRenderingContext2D.cpp
@@ -4953,6 +4953,10 @@ CanvasRenderingContext2D::DrawWindow(nsGlobalWindow& aWindow, double aX,
   EnsureTarget();
   if (drawDT) {
     RefPtr<SourceSurface> snapshot = drawDT->Snapshot();
+    if (NS_WARN_IF(!snapshot)) {
+      aError.Throw(NS_ERROR_FAILURE);
+      return;
+    }
     RefPtr<DataSourceSurface> data = snapshot->GetDataSurface();
 
     DataSourceSurface::MappedSurface rawData;