Wipe memory reliably in Memory::Zero

src/Platform/Buffer.cpp

@@ -77,7 +77,7 @@ namespace VeraCrypt
 	void Buffer::Erase ()
 	{
 		if (DataSize > 0)
-			burn (DataPtr, DataSize);
+			Memory::SecureErase (DataPtr, DataSize);
 	}
 
 	void Buffer::Free ()

src/Platform/Buffer.h

@@ -53,7 +53,7 @@ namespace VeraCrypt
 
 		operator uint8 * () const { return DataPtr; }
 		void CopyFrom (const ConstBufferPtr &bufferPtr) const;
-		void Erase () const { Zero(); }
+		void Erase () const { Memory::SecureErase (DataPtr, DataSize); }
 		uint8 *Get () const { return DataPtr; }
 		BufferPtr GetRange (size_t offset, size_t size) const;
 		void Set (uint8 *data, size_t size) { DataPtr = data; DataSize = size; }

src/Platform/Memory.cpp

@@ -61,6 +61,14 @@ namespace VeraCrypt
 		memcpy (memoryDestination, memorySource, size);
 	}
 
+	// Secure erasure of sensitive data: the volatile writes of burn() cannot
+	// be elided by the optimiser even when the buffer is not read afterwards.
+	// Use Zero() instead for ordinary zero-initialization.
+	void Memory::SecureErase (void *memory, size_t size)
+	{
+		burn (memory, size);
+	}
+
 	void Memory::Zero (void *memory, size_t size)
 	{
 		memset (memory, 0, size);

src/Platform/Memory.h

@@ -79,6 +79,7 @@ namespace VeraCrypt
 		static void Copy (void *memoryDestination, const void *memorySource, size_t size);
 		static void Free (void *memory);
 		static void FreeAligned (void *memory);
+		static void SecureErase (void *memory, size_t size);
 		static void Zero (void *memory, size_t size);
 	};