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Unified Diff: third_party/afl/src/afl-gcc.c

Issue 2075883002: Add American Fuzzy Lop (afl) to third_party/afl/ (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Fix nits Created 4 years, 6 months ago
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Index: third_party/afl/src/afl-gcc.c
diff --git a/third_party/afl/src/afl-gcc.c b/third_party/afl/src/afl-gcc.c
new file mode 100644
index 0000000000000000000000000000000000000000..b6cbc05c801fdda24e0cc66508c602d100b68806
--- /dev/null
+++ b/third_party/afl/src/afl-gcc.c
@@ -0,0 +1,318 @@
+/*
+ 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.
+ You may obtain a copy of the License at:
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ This program is a drop-in replacement for GCC or clang. The most common way
+ of using it is to pass the path to afl-gcc or afl-clang via CC when invoking
+ ./configure.
+
+ (Of course, use CXX and point it to afl-g++ / afl-clang++ for C++ code.)
+
+ The wrapper needs to know the path to afl-as (renamed to 'as'). The default
+ is /usr/local/lib/afl/. A convenient way to specify alternative directories
+ would be to set AFL_PATH.
+
+ If AFL_HARDEN is set, the wrapper will compile the target app with various
+ hardening options that may help detect memory management issues more
+ reliably. You can also specify AFL_USE_ASAN to enable ASAN.
+
+ If you want to call a non-default compiler as a next step of the chain,
+ specify its location via AFL_CC or AFL_CXX.
+
+ */
+
+#define AFL_MAIN
+
+#include "config.h"
+#include "types.h"
+#include "debug.h"
+#include "alloc-inl.h"
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+
+static u8* as_path; /* Path to the AFL 'as' wrapper */
+static u8** cc_params; /* Parameters passed to the real CC */
+static u32 cc_par_cnt = 1; /* Param count, including argv0 */
+static u8 be_quiet, /* Quiet mode */
+ clang_mode; /* Invoked as afl-clang*? */
+
+
+/* Try to find our "fake" GNU assembler in AFL_PATH or at the location derived
+ from argv[0]. If that fails, abort. */
+
+static void find_as(u8* argv0) {
+
+ u8 *afl_path = getenv("AFL_PATH");
+ u8 *slash, *tmp;
+
+ if (afl_path) {
+
+ tmp = alloc_printf("%s/as", afl_path);
+
+ if (!access(tmp, X_OK)) {
+ as_path = afl_path;
+ ck_free(tmp);
+ return;
+ }
+
+ ck_free(tmp);
+
+ }
+
+ slash = strrchr(argv0, '/');
+
+ if (slash) {
+
+ u8 *dir;
+
+ *slash = 0;
+ dir = ck_strdup(argv0);
+ *slash = '/';
+
+ tmp = alloc_printf("%s/afl-as", dir);
+
+ if (!access(tmp, X_OK)) {
+ as_path = dir;
+ ck_free(tmp);
+ return;
+ }
+
+ ck_free(tmp);
+ ck_free(dir);
+
+ }
+
+ if (!access(AFL_PATH "/as", X_OK)) {
+ as_path = AFL_PATH;
+ return;
+ }
+
+ FATAL("Unable to find AFL wrapper binary for 'as'. Please set AFL_PATH");
+
+}
+
+
+/* Copy argv to cc_params, making the necessary edits. */
+
+static void edit_params(u32 argc, char** argv) {
+
+ u8 fortify_set = 0, asan_set = 0;
+ u8 *name;
+
+#if defined(__FreeBSD__) && defined(__x86_64__)
+ u8 m32_set = 0;
+#endif
+
+ cc_params = ck_alloc((argc + 64) * sizeof(u8*));
+
+ name = strrchr(argv[0], '/');
+ if (!name) name = argv[0]; else name++;
+
+ if (!strncmp(name, "afl-clang", 9)) {
+
+ clang_mode = 1;
+
+ setenv(CLANG_ENV_VAR, "1", 1);
+
+ if (!strcmp(name, "afl-clang++")) {
+ u8* alt_cxx = getenv("AFL_CXX");
+ cc_params[0] = alt_cxx ? alt_cxx : (u8*)"clang++";
+ } else {
+ u8* alt_cc = getenv("AFL_CC");
+ cc_params[0] = alt_cc ? alt_cc : (u8*)"clang";
+ }
+
+ } else {
+
+ /* With GCJ and Eclipse installed, you can actually compile Java! The
+ instrumentation will work (amazingly). Alas, unhandled exceptions do
+ not call abort(), so afl-fuzz would need to be modified to equate
+ non-zero exit codes with crash conditions when working with Java
+ binaries. Meh. */
+
+#ifdef __APPLE__
+
+ if (!strcmp(name, "afl-g++")) cc_params[0] = getenv("AFL_CXX");
+ else if (!strcmp(name, "afl-gcj")) cc_params[0] = getenv("AFL_GCJ");
+ else cc_params[0] = getenv("AFL_CC");
+
+ if (!cc_params[0]) {
+
+ SAYF("\n" cLRD "[-] " cRST
+ "On Apple systems, 'gcc' is usually just a wrapper for clang. Please use the\n"
+ " 'afl-clang' utility instead of 'afl-gcc'. If you really have GCC installed,\n"
+ " set AFL_CC or AFL_CXX to specify the correct path to that compiler.\n");
+
+ FATAL("AFL_CC or AFL_CXX required on MacOS X");
+
+ }
+
+#else
+
+ if (!strcmp(name, "afl-g++")) {
+ u8* alt_cxx = getenv("AFL_CXX");
+ cc_params[0] = alt_cxx ? alt_cxx : (u8*)"g++";
+ } else if (!strcmp(name, "afl-gcj")) {
+ u8* alt_cc = getenv("AFL_GCJ");
+ cc_params[0] = alt_cc ? alt_cc : (u8*)"gcj";
+ } else {
+ u8* alt_cc = getenv("AFL_CC");
+ cc_params[0] = alt_cc ? alt_cc : (u8*)"gcc";
+ }
+
+#endif /* __APPLE__ */
+
+ }
+
+ while (--argc) {
+ u8* cur = *(++argv);
+
+ if (!strncmp(cur, "-B", 2)) {
+
+ if (!be_quiet) WARNF("-B is already set, overriding");
+
+ if (!cur[2] && argc > 1) { argc--; argv++; }
+ continue;
+
+ }
+
+ if (!strcmp(cur, "-integrated-as")) continue;
+
+ if (!strcmp(cur, "-pipe")) continue;
+
+#if defined(__FreeBSD__) && defined(__x86_64__)
+ if (!strcmp(cur, "-m32")) m32_set = 1;
+#endif
+
+ if (!strcmp(cur, "-fsanitize=address") ||
+ !strcmp(cur, "-fsanitize=memory")) asan_set = 1;
+
+ if (strstr(cur, "FORTIFY_SOURCE")) fortify_set = 1;
+
+ cc_params[cc_par_cnt++] = cur;
+
+ }
+
+ cc_params[cc_par_cnt++] = "-B";
+ cc_params[cc_par_cnt++] = as_path;
+
+ if (clang_mode)
+ cc_params[cc_par_cnt++] = "-no-integrated-as";
+
+ if (getenv("AFL_HARDEN")) {
+
+ cc_params[cc_par_cnt++] = "-fstack-protector-all";
+
+ if (!fortify_set)
+ cc_params[cc_par_cnt++] = "-D_FORTIFY_SOURCE=2";
+
+ }
+
+ 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");
+
+ } 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_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. */
+
+ if (!clang_mode || !m32_set)
+ cc_params[cc_par_cnt++] = "-g";
+
+#else
+
+ cc_params[cc_par_cnt++] = "-g";
+
+#endif
+
+ cc_params[cc_par_cnt++] = "-O3";
+ cc_params[cc_par_cnt++] = "-funroll-loops";
+
+ /* Two indicators that you're building for fuzzing; one of them is
+ AFL-specific, the other is shared with libfuzzer. */
+
+ cc_params[cc_par_cnt++] = "-D__AFL_COMPILER=1";
+ cc_params[cc_par_cnt++] = "-DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION=1";
+
+ }
+
+ cc_params[cc_par_cnt] = NULL;
+
+}
+
+
+/* Main entry point */
+
+int main(int argc, char** argv) {
+
+ if (isatty(2) && !getenv("AFL_QUIET")) {
+
+ SAYF(cCYA "afl-cc " cBRI VERSION cRST " by <lcamtuf@google.com>\n");
+
+ } else be_quiet = 1;
+
+ if (argc < 2) {
+
+ SAYF("\n"
+ "This is a helper application for afl-fuzz. It serves as a drop-in replacement\n"
+ "for gcc or clang, letting you recompile third-party code with the required\n"
+ "runtime instrumentation. A common use pattern would be one of the following:\n\n"
+
+ " CC=%s/afl-gcc ./configure\n"
+ " 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;
+
+}
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