Roll AFL 2.31b:2.38b and switch coverage to use trace-pc-guard.

third_party/afl/src/afl-gcc.c

 /*
    american fuzzy lop - wrapper for GCC and clang
    ----------------------------------------------
 
    Written and maintained by Michal Zalewski <lcamtuf@google.com>
 
    Copyright 2013, 2014, 2015 Google Inc. All rights reserved.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
@@ skipping 211 matching lines @@
   }
 
   if (asan_set) {
 
     /* Pass this on to afl-as to adjust map density. */
 
     setenv("AFL_USE_ASAN", "1", 1);
 
   } else if (getenv("AFL_USE_ASAN")) {
 
-    cc_params[cc_par_cnt++] = "-fsanitize=address";
-
     if (getenv("AFL_USE_MSAN"))
       FATAL("ASAN and MSAN are mutually exclusive");
 
+    if (getenv("AFL_HARDEN"))
+      FATAL("ASAN and AFL_HARDEN are mutually exclusive");
+
+    cc_params[cc_par_cnt++] = "-U_FORTIFY_SOURCE";
+    cc_params[cc_par_cnt++] = "-fsanitize=address";
+
   } else if (getenv("AFL_USE_MSAN")) {
 
-    cc_params[cc_par_cnt++] = "-fsanitize=memory";
-
     if (getenv("AFL_USE_ASAN"))
       FATAL("ASAN and MSAN are mutually exclusive");
 
+    if (getenv("AFL_HARDEN"))
+      FATAL("MSAN and AFL_HARDEN are mutually exclusive");
+
+    cc_params[cc_par_cnt++] = "-U_FORTIFY_SOURCE";
+    cc_params[cc_par_cnt++] = "-fsanitize=memory";
+
+
   }
 
   if (!getenv("AFL_DONT_OPTIMIZE")) {
 
 #if defined(__FreeBSD__) && defined(__x86_64__)
 
     /* On 64-bit FreeBSD systems, clang -g -m32 is broken, but -m32 itself
        works OK. This has nothing to do with us, but let's avoid triggering
        that bug. */
 
@@ skipping 53 matching lines @@
          "  CXX=%s/afl-g++ ./configure\n\n"
 
          "You can specify custom next-stage toolchain via AFL_CC, AFL_CXX, and AFL_AS.\n"
          "Setting AFL_HARDEN enables hardening optimizations in the compiled code.\n\n",
          BIN_PATH, BIN_PATH);
 
     exit(1);
 
   }
 
-
   find_as(argv[0]);
 
   edit_params(argc, argv);
 
   execvp(cc_params[0], (char**)cc_params);
 
   FATAL("Oops, failed to execute '%s' - check your PATH", cc_params[0]);
 
   return 0;
 
 }