stdio-common/bug-vfprintf-nargs.c

   1 /* Test for vfprintf nargs allocation overflow (BZ #13656).
   2    Copyright (C) 2012-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <stdint.h>
  22 #include <unistd.h>
  23 #include <inttypes.h>
  24 #include <string.h>
  25 #include <signal.h>
  26
  27 static int
  28 format_failed (const char *fmt, const char *expected)
  29 {
  30   char output[80];
  31
  32   printf ("%s : ", fmt);
  33
  34   memset (output, 0, sizeof output);
  35   /* Having sprintf itself detect a failure is good.  */
  36   if (sprintf (output, fmt, 1, 2, 3, "test") > 0
  37       && strcmp (output, expected) != 0)
  38     {
  39       printf ("FAIL (output '%s' != expected '%s')\n", output, expected);
  40       return 1;
  41     }
  42   puts ("ok");
  43   return 0;
  44 }
  45
  46 static int
  47 do_test (void)
  48 {
  49   int rc = 0;
  50   char buf[64];
  51
  52   /* Regular positionals work.  */
  53   if (format_failed ("%1$d", "1") != 0)
  54     rc = 1;
  55
  56   /* Regular width positionals work.  */
  57   if (format_failed ("%1$*2$d", " 1") != 0)
  58     rc = 1;
  59
  60   /* Positional arguments are constructed via read_int, so nargs can only
  61      overflow on 32-bit systems.  On 64-bit systems, it will attempt to
  62      allocate a giant amount of memory and possibly crash, which is the
  63      expected situation.  Since the 64-bit behavior is arch-specific, only
  64      test this on 32-bit systems.  */
  65   if (sizeof (long int) == 4)
  66     {
  67       sprintf (buf, "%%1$d %%%" PRIdPTR "$d",
  68                (intptr_t) (UINT32_MAX / sizeof (int)));
  69       if (format_failed (buf, "1 %$d") != 0)
  70         rc = 1;
  71     }
  72
  73   return rc;
  74 }
  75
  76 #define TEST_FUNCTION do_test ()
  77 #include "../test-skeleton.c"