Index: lib/asan/asan_activation.cc
===================================================================
--- lib/asan/asan_activation.cc
+++ lib/asan/asan_activation.cc
@@ -47,6 +47,7 @@
     FlagParser parser;
     RegisterActivationFlags(&parser, &f, &cf);
 
+    cf.SetDefaults();
     // Copy the current activation flags.
     allocator_options.CopyTo(&f, &cf);
     cf.malloc_context_size = malloc_context_size;