stdlib/test-bz22786.c

   1 /* Bug 22786: test for buffer overflow in realpath.
   2    Copyright (C) 2018 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    <http://www.gnu.org/licenses/>.  */
  18
  19 /* This file must be run from within a directory called "stdlib".  */
  20
  21 #include <errno.h>
  22 #include <limits.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <unistd.h>
  27 #include <sys/stat.h>
  28 #include <sys/types.h>
  29 #include <support/test-driver.h>
  30 #include <libc-diag.h>
  31
  32 static int
  33 do_test (void)
  34 {
  35   const char dir[] = "bz22786";
  36   const char lnk[] = "bz22786/symlink";
  37
  38   rmdir (dir);
  39   if (mkdir (dir, 0755) != 0 && errno != EEXIST)
  40     {
  41       printf ("mkdir %s: %m\n", dir);
  42       return EXIT_FAILURE;
  43     }
  44   if (symlink (".", lnk) != 0 && errno != EEXIST)
  45     {
  46       printf ("symlink (%s, %s): %m\n", dir, lnk);
  47       return EXIT_FAILURE;
  48     }
  49
  50   const size_t path_len = (size_t) INT_MAX + 1;
  51
  52   DIAG_PUSH_NEEDS_COMMENT;
  53 #if __GNUC_PREREQ (7, 0)
  54   /* GCC 7 warns about too-large allocations; here we need such
  55      allocation to succeed for the test to work.  */
  56   DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
  57 #endif
  58   char *path = malloc (path_len);
  59   DIAG_POP_NEEDS_COMMENT;
  60
  61   if (path == NULL)
  62     {
  63       printf ("malloc (%zu): %m\n", path_len);
  64       return EXIT_UNSUPPORTED;
  65     }
  66
  67   /* Construct very long path = "bz22786/symlink/aaaa....."  */
  68   char *p = mempcpy (path, lnk, sizeof (lnk) - 1);
  69   *(p++) = '/';
  70   memset (p, 'a', path_len - (path - p) - 2);
  71   p[path_len - (path - p) - 1] = '\0';
  72
  73   /* This call crashes before the fix for bz22786 on 32-bit platforms.  */
  74   p = realpath (path, NULL);
  75
  76   if (p != NULL || errno != ENAMETOOLONG)
  77     {
  78       printf ("realpath: %s (%m)", p);
  79       return EXIT_FAILURE;
  80     }
  81
  82   /* Cleanup.  */
  83   unlink (lnk);
  84   rmdir (dir);
  85
  86   return 0;
  87 }
  88
  89 #define TEST_FUNCTION do_test
  90 #include <support/test-driver.c>