Index: lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
@@ -55,7 +55,10 @@
   // own demangler (libc++abi's implementation could be adapted so that
   // it does not allocate). For now, we just call it anyway, and we leak
   // the returned value.
-  if (__cxxabiv1::__cxa_demangle)
+  // Explicitly check for mangled external names (starting with "_Z") as
+  // __cxa_demangle also handles type mangling, which conflicts with
+  // unmangled names such as "f" or "m".
+  if (__cxxabiv1::__cxa_demangle && name && name[0] == '_' && name[1] == 'Z')
     if (const char *demangled_name =
           __cxxabiv1::__cxa_demangle(name, 0, 0, 0))
       return demangled_name;