crash if getNativeBuffer() called on NULL GraphicBuffer

If getNativeBuffer() is called on a NULL GraphicBuffer the
static_cast of this from GraphicBuffer* to ANativeWindowBuffer*
will return a small pointer like (ANativeWindowBuffer*)0x10.
This value can propagate past NULL checks until it causes a crash
far away from the original NULL pointer.  Crash immediately
instead.

Change-Id: Id614b9eb1484108b3c3c733545309844c4b87532

diff --git a/libs/ui/GraphicBuffer.cpp b/libs/ui/GraphicBuffer.cpp
index e21dc53..9b0bd60 100644 (file)
--- a/libs/ui/GraphicBuffer.cpp
+++ b/libs/ui/GraphicBuffer.cpp
@@ -126,6 +126,7 @@ void GraphicBuffer::dumpAllocationsToSystemLog()
 
 ANativeWindowBuffer* GraphicBuffer::getNativeBuffer() const
 {
+    LOG_ALWAYS_FATAL_IF(this == NULL, "getNativeBuffer() called on NULL GraphicBuffer");
     return static_cast<ANativeWindowBuffer*>(
             const_cast<GraphicBuffer*>(this));
 }