Checking structure sizes before reading them from memory to avoid overflowing the buffer's stream.

src/core/SkMatrix.cpp

Index: src/core/SkMatrix.cpp
diff --git a/src/core/SkMatrix.cpp b/src/core/SkMatrix.cpp
index 5bcb35b298874088004f5c39fba7133e85a0c323..192fc1b091edde133ccce2a9b89089371f6503b7 100644
--- a/src/core/SkMatrix.cpp
+++ b/src/core/SkMatrix.cpp
@@ -1923,18 +1923,23 @@ const SkMatrix& SkMatrix::InvalidMatrix() {
 
 uint32_t SkMatrix::writeToMemory(void* buffer) const {
     // TODO write less for simple matrices
+    static const uint32_t sizeInMemory = 9 * sizeof(SkScalar);
     if (buffer) {
-        memcpy(buffer, fMat, 9 * sizeof(SkScalar));
+        memcpy(buffer, fMat, sizeInMemory);
     }
-    return 9 * sizeof(SkScalar);
+    return sizeInMemory;
 }
 
-uint32_t SkMatrix::readFromMemory(const void* buffer) {
+uint32_t SkMatrix::readFromMemory(const void* buffer, uint32_t length) {
+    static const uint32_t sizeInMemory = 9 * sizeof(SkScalar);
+    if (length < sizeInMemory) {
+        return 0;
+    }
     if (buffer) {
-        memcpy(fMat, buffer, 9 * sizeof(SkScalar));
+        memcpy(fMat, buffer, sizeInMemory);
         this->setTypeMask(kUnknown_Mask);
     }
-    return 9 * sizeof(SkScalar);
+    return sizeInMemory;
 }
 
 #ifdef SK_DEVELOPER