Limit size of loaded file systems

If a disc image is malformed in a specific way, Dolphin
will try to allocate a lot of memory, making it crash.
To avoid that, this change adds an artificial limit for
the size of file systems that Dolphin will try to load.

Source/Core/DiscIO/FileSystemGCWii.cpp

@@ -276,6 +276,18 @@ void CFileSystemGCWii::InitFileSystem()
 	if (!Root.IsDirectory())
 		return;
 
+	// 12 bytes (the size of a file entry) times 10 * 1024 * 1024 is 120 MiB,
+	// more than total RAM in a Wii. No file system should use anywhere near that much.
+	static const u32 ARBITRARY_FILE_SYSTEM_SIZE_LIMIT = 10 * 1024 * 1024;
+	if (Root.m_FileSize > ARBITRARY_FILE_SYSTEM_SIZE_LIMIT)
+	{
+		// Without this check, Dolphin can crash by trying to allocate too much
+		// memory when loading the file systems of certain malformed disc images.
+
+		ERROR_LOG(DISCIO, "File system is abnormally large! Aborting loading");
+		return;
+	}
+
 	if (m_FileInfoVector.size())
 		PanicAlert("Wtf?");
 	u64 NameTableOffset = FSTOffset;