Don't memcpy from a null source. Found by UBSan

llvm-svn: 264114

diff --git a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
index 34c48a5..03e081a 100644 (file)
--- a/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
+++ b/lld/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
@@ -1066,6 +1066,8 @@ void MachOFileLayout::appendSymbols(const std::vector<Symbol> &symbols,
 }
 
 void MachOFileLayout::writeFunctionStartsInfo() {
+  if (!_functionStartsSize)
+    return;
   memcpy(&_buffer[_startOfFunctionStarts], _file.functionStarts.data(),
          _functionStartsSize);
 }