libc/bionic/ssp.cpp

/*
 * Copyright (C) 2008 The Android Open Source Project
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  * Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  * Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <ctype.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/auxv.h>
#include <unistd.h>

#include "bionic_ssp.h"
#include "logd.h"

uintptr_t __stack_chk_guard = NULL;

static void __attribute__((constructor)) __init_stack_check_guard() {
  // AT_RANDOM is a pointer to 16 bytes of randomness on the stack.
  __stack_chk_guard = *reinterpret_cast<uintptr_t*>(getauxval(AT_RANDOM));
}

// This is the crash handler.
// Does a best effort at logging and calls _exit to terminate
// the process immediately (without atexit handlers, etc.).
void __stack_chk_fail() {
  // Immediately block all (but SIGABRT) signal handlers from running code.
  sigset_t sigmask;
  sigfillset(&sigmask);
  sigdelset(&sigmask, SIGABRT);
  sigprocmask(SIG_BLOCK, &sigmask, NULL);

  // Use /proc/self/exe link to obtain the program name for logging
  // purposes. If it's not available, we set it to "<unknown>".
  char path[PATH_MAX];
  int count;
  if ((count = readlink("/proc/self/exe", path, sizeof(path) - 1)) == -1) {
    strlcpy(path, "<unknown>", sizeof(path));
  } else {
    path[count] = '\0';
  }

  // Do a best effort at logging.
  __libc_android_log_write(ANDROID_LOG_FATAL, path, "stack corruption detected: aborted");

  // Make sure there is no default action for SIGABRT.
  struct sigaction sa;
  memset(&sa, 0, sizeof(sa));
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  sa.sa_handler = SIG_DFL;
  sigaction(SIGABRT, &sa, NULL);

  // Terminate the process and exit immediately.
  kill(getpid(), SIGABRT);

  _exit(127);
}