1 files changed, 304 insertions, 0 deletions
diff --git a/gcc_plugin/afl-gcc-rt.o.c b/gcc_plugin/afl-gcc-rt.o.c
new file mode 100644
index 00000000..5b70a247
--- /dev/null
+++ b/gcc_plugin/afl-gcc-rt.o.c
@@ -0,0 +1,304 @@
+/*
+   american fuzzy lop - GCC plugin instrumentation bootstrap
+   ---------------------------------------------------------
+
+   Written by Austin Seipp <aseipp@pobox.com> and
+              Laszlo Szekeres <lszekeres@google.com> and
+              Michal Zalewski
+
+   GCC integration design is based on the LLVM design, which comes
+   from Laszlo Szekeres.
+
+   Copyright 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 code is the rewrite of afl-as.h's main_payload.
+
+*/
+
+#ifdef __ANDROID__
+#include "android-ashmem.h"
+#endif
+#include "../config.h"
+#include "../types.h"
+
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+#include <string.h>
+#include <assert.h>
+
+#include <sys/mman.h>
+#include <sys/shm.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+
+#include <sys/mman.h>
+#include <fcntl.h>
+
+/* Globals needed by the injected instrumentation. The __afl_area_initial region
+   is used for instrumentation output before __afl_map_shm() has a chance to
+   run. It will end up as .comm, so it shouldn't be too wasteful. */
+
+u8  __afl_area_initial[MAP_SIZE];
+u8 *__afl_area_ptr = __afl_area_initial;
+
+#ifdef __ANDROID__
+u32 __afl_prev_loc;
+#else
+__thread u32 __afl_prev_loc;
+#endif
+
+/* Trace a basic block with some ID */
+void __afl_trace(u32 x) {
+
+  u32 l = __afl_prev_loc;
+
+#if 0 /* enable for neverZero feature. By default disabled since too inefficient :-( */
+  /* @Marc: avoid conditional jumps here */
+  __afl_area_ptr[l ^ x] += 1 + (__afl_area_ptr[l ^ x] == (u8)~0);
+#else
+  ++__afl_area_ptr[l ^ x];
+#endif
+
+  __afl_prev_loc = (x >> 1);
+  return;
+
+}
+
+/* Running in persistent mode? */
+
+static u8 is_persistent;
+
+/* SHM setup. */
+
+static void __afl_map_shm(void) {
+
+  u8 *id_str = getenv(SHM_ENV_VAR);
+
+  /* If we're running under AFL, attach to the appropriate region, replacing the
+     early-stage __afl_area_initial region that is needed to allow some really
+     hacky .init code to work correctly in projects such as OpenSSL. */
+
+  if (id_str) {
+
+#ifdef USEMMAP
+    const char*    shm_file_path = id_str;
+    int            shm_fd = -1;
+    unsigned char* shm_base = NULL;
+
+    /* create the shared memory segment as if it was a file */
+    shm_fd = shm_open(shm_file_path, O_RDWR, 0600);
+    if (shm_fd == -1) {
+
+      printf("shm_open() failed\n");
+      exit(1);
+
+    }
+
+    /* map the shared memory segment to the address space of the process */
+    shm_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
+    if (shm_base == MAP_FAILED) {
+
+      close(shm_fd);
+      shm_fd = -1;
+
+      printf("mmap() failed\n");
+      exit(2);
+
+    }
+
+    __afl_area_ptr = shm_base;
+#else
+    u32 shm_id = atoi(id_str);
+
+    __afl_area_ptr = shmat(shm_id, NULL, 0);
+#endif
+
+    /* Whooooops. */
+
+    if (__afl_area_ptr == (void *)-1) exit(1);
+
+    /* Write something into the bitmap so that even with low AFL_INST_RATIO,
+       our parent doesn't give up on us. */
+
+    __afl_area_ptr[0] = 1;
+
+  }
+
+}
+
+/* Fork server logic. */
+
+static void __afl_start_forkserver(void) {
+
+  static u8 tmp[4];
+  s32       child_pid;
+
+  u8 child_stopped = 0;
+
+  void (*old_sigchld_handler)(int) = signal(SIGCHLD, SIG_DFL);
+
+  /* Phone home and tell the parent that we're OK. If parent isn't there,
+     assume we're not running in forkserver mode and just execute program. */
+
+  if (write(FORKSRV_FD + 1, tmp, 4) != 4) return;
+
+  while (1) {
+
+    u32 was_killed;
+    int status;
+
+    /* Wait for parent by reading from the pipe. Abort if read fails. */
+
+    if (read(FORKSRV_FD, &was_killed, 4) != 4) exit(1);
+
+    /* If we stopped the child in persistent mode, but there was a race
+       condition and afl-fuzz already issued SIGKILL, write off the old
+       process. */
+
+    if (child_stopped && was_killed) {
+
+      child_stopped = 0;
+      if (waitpid(child_pid, &status, 0) < 0) exit(1);
+
+    }
+
+    if (!child_stopped) {
+
+      /* Once woken up, create a clone of our process. */
+
+      child_pid = fork();
+      if (child_pid < 0) exit(1);
+
+      /* In child process: close fds, resume execution. */
+
+      if (!child_pid) {
+
+        signal(SIGCHLD, old_sigchld_handler);
+
+        close(FORKSRV_FD);
+        close(FORKSRV_FD + 1);
+        return;
+
+      }
+
+    } else {
+
+      /* Special handling for persistent mode: if the child is alive but
+         currently stopped, simply restart it with SIGCONT. */
+
+      kill(child_pid, SIGCONT);
+      child_stopped = 0;
+
+    }
+
+    /* In parent process: write PID to pipe, then wait for child. */
+
+    if (write(FORKSRV_FD + 1, &child_pid, 4) != 4) exit(1);
+
+    if (waitpid(child_pid, &status, is_persistent ? WUNTRACED : 0) < 0) exit(1);
+
+    /* In persistent mode, the child stops itself with SIGSTOP to indicate
+       a successful run. In this case, we want to wake it up without forking
+       again. */
+
+    if (WIFSTOPPED(status)) child_stopped = 1;
+
+    /* Relay wait status to pipe, then loop back. */
+
+    if (write(FORKSRV_FD + 1, &status, 4) != 4) exit(1);
+
+  }
+
+}
+
+/* A simplified persistent mode handler, used as explained in README.llvm. */
+
+int __afl_persistent_loop(unsigned int max_cnt) {
+
+  static u8  first_pass = 1;
+  static u32 cycle_cnt;
+
+  if (first_pass) {
+
+    /* Make sure that every iteration of __AFL_LOOP() starts with a clean slate.
+       On subsequent calls, the parent will take care of that, but on the first
+       iteration, it's our job to erase any trace of whatever happened
+       before the loop. */
+
+    if (is_persistent) {
+
+      memset(__afl_area_ptr, 0, MAP_SIZE);
+      __afl_area_ptr[0] = 1;
+      __afl_prev_loc = 0;
+
+    }
+
+    cycle_cnt = max_cnt;
+    first_pass = 0;
+    return 1;
+
+  }
+
+  if (is_persistent) {
+
+    if (--cycle_cnt) {
+
+      raise(SIGSTOP);
+
+      __afl_area_ptr[0] = 1;
+      __afl_prev_loc = 0;
+
+      return 1;
+
+    } else {
+
+      /* When exiting __AFL_LOOP(), make sure that the subsequent code that
+         follows the loop is not traced. We do that by pivoting back to the
+         dummy output region. */
+
+      __afl_area_ptr = __afl_area_initial;
+
+    }
+
+  }
+
+    return 0;
+
+}
+
+/* This one can be called from user code when deferred forkserver mode
+    is enabled. */
+
+void __afl_manual_init(void) {
+
+  static u8 init_done;
+
+  if (!init_done) {
+
+    __afl_map_shm();
+    __afl_start_forkserver();
+    init_done = 1;
+
+  }
+
+}
+
+/* Proper initialization routine. */
+
+__attribute__((constructor(101))) void __afl_auto_init(void) {
+
+  is_persistent = !!getenv(PERSIST_ENV_VAR);
+
+  if (getenv(DEFER_ENV_VAR)) return;
+
+  __afl_manual_init();
+
+}
+