SkGrPixelRef can only reference the subset of the Surface specified by its SkImageInfo

BUG=skia:
R=bsalomon@google.com, halcanary@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/138143022

git-svn-id: http://skia.googlecode.com/svn/trunk@13217 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 7 insertions, 2 deletions

diff --git a/src/gpu/SkGrPixelRef.cpp b/src/gpu/SkGrPixelRef.cpp
index fdf94870cc..18fefcc789 100644
--- a/src/gpu/SkGrPixelRef.cpp
+++ b/src/gpu/SkGrPixelRef.cpp
@@ -127,6 +127,11 @@ SkGrPixelRef::SkGrPixelRef(const SkImageInfo& info, GrSurface* surface,
     }
     fUnlock = transferCacheLock;
     SkSafeRef(surface);
+
+    if (fSurface) {
+        SkASSERT(info.fWidth <= fSurface->width());
+        SkASSERT(info.fHeight <= fSurface->height());
+    }
 }
 
 SkGrPixelRef::~SkGrPixelRef() {
@@ -174,9 +179,9 @@ bool SkGrPixelRef::onReadPixels(SkBitmap* dst, const SkIRect* subset) {
         height = subset->height();
     } else {
         left = 0;
-        width = fSurface->width();
+        width = this->info().fWidth;
         top = 0;
-        height = fSurface->height();
+        height = this->info().fHeight;
     }
     if (!dst->allocPixels(SkImageInfo::MakeN32Premul(width, height))) {
         SkDebugf("SkGrPixelRef::onReadPixels failed to alloc bitmap for result!\n");