stdio-common/bug-vfprintf-nargs.c

   1 /* Test for vfprintf nargs allocation overflow (BZ #13656).
   2    Copyright (C) 2012-2020 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Kees Cook <keescook@chromium.org>, 2012.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <stdint.h>
  23 #include <unistd.h>
  24 #include <inttypes.h>
  25 #include <string.h>
  26 #include <signal.h>
  27
  28 static int
  29 format_failed (const char *fmt, const char *expected)
  30 {
  31   char output[80];
  32
  33   printf ("%s : ", fmt);
  34
  35   memset (output, 0, sizeof output);
  36   /* Having sprintf itself detect a failure is good.  */
  37   if (sprintf (output, fmt, 1, 2, 3, "test") > 0
  38       && strcmp (output, expected) != 0)
  39     {
  40       printf ("FAIL (output '%s' != expected '%s')\n", output, expected);
  41       return 1;
  42     }
  43   puts ("ok");
  44   return 0;
  45 }
  46
  47 static int
  48 do_test (void)
  49 {
  50   int rc = 0;
  51   char buf[64];
  52
  53   /* Regular positionals work.  */
  54   if (format_failed ("%1$d", "1") != 0)
  55     rc = 1;
  56
  57   /* Regular width positionals work.  */
  58   if (format_failed ("%1$*2$d", " 1") != 0)
  59     rc = 1;
  60
  61   /* Positional arguments are constructed via read_int, so nargs can only
  62      overflow on 32-bit systems.  On 64-bit systems, it will attempt to
  63      allocate a giant amount of memory and possibly crash, which is the
  64      expected situation.  Since the 64-bit behavior is arch-specific, only
  65      test this on 32-bit systems.  */
  66   if (sizeof (long int) == 4)
  67     {
  68       sprintf (buf, "%%1$d %%%" PRIdPTR "$d",
  69                (intptr_t) (UINT32_MAX / sizeof (int)));
  70       if (format_failed (buf, "1 %$d") != 0)
  71         rc = 1;
  72     }
  73
  74   return rc;
  75 }
  76
  77 #define TEST_FUNCTION do_test ()
  78 #include "../test-skeleton.c"