alpine 3.6
race weakness #31

5

Weakness Breakdown


Definition:

A race condition exists when parallel code accesses shared data without proper coordination. An attack that uses a race-condition weakness takes advantage of the unsafe data access to manipulate how one of the parallel sections of code reacts. Even though each process runs as intended, the outcome is unexpected. For example, consider a bank service that depends on an encryption key that it reads from a known location. An independent cryptography service is responsible for generating the key and placing it where the bank is expected to read it in a timely manner. If the bank and cryptography services do not coordinate with each other, then the bank may read a blank encryption key before cryptography writes the key to the location. This can effectively turn off all encryption for the bank without either service, or the administrator, knowing that something has gone wrong.

Warning code(s):

This accepts filename arguments; if an attacker can move those files, a race condition results..

File Name:

cogl/src/cogl-1.22.2/deps/glib/gstdio.c

Context:

The highlighted line of code below is the trigger point of this particular Alpine 3.6 race weakness.

  */
int
g_chmod (const gchar *filename,
	 int          mode)
{
#ifdef G_OS_WIN32
  wchar_t *wfilename = g_utf8_to_utf16 (filename, -1, NULL, NULL, NULL);
  int retval;
  int save_errno;
    
  if (wfilename == NULL)
    {
      errno = EINVAL;
      return -1;
    }

  retval = _wchmod (wfilename, mode);
  save_errno = errno;

  g_free (wfilename);

  errno = save_errno;
  return retval;
#else
  return chmod (filename, mode);
#endif
}
/**
 * g_open:
 * @filename: a pathname in the GLib file name encoding (UTF-8 on Windows)
 * @flags: as in open()
 * @mode: as in open()
 *
 * A wrapper for the POSIX open() function. The open() function is
 * used to convert a pathname into a file descriptor.
 *
 * On POSIX systems file descriptors are implemented by the operating
 * system. On Windows, it's the C library that implements open() and
 * file descriptors. The actual Win32 API for opening files is quite
 * different, see MSDN documentation for CreateFile(). The Win32 API
 * uses file handles, which are more randomish integers, not small
 * integers like file descriptors.
 *
 * Because file descriptors are specific to the C library on Windows,
 * the file descriptor returned by this function makes sense only to
 * functions in the same C library. Thus if the GLib-using code uses a
 * different C library than GLib does, the file descriptor returned by
 * this function cannot be passed to C library functions like write()
 * or read().
 * 

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