debug/tst-sprintf-fortify-rdonly.c

   1 /* Testcase for BZ 30932.
   2    Copyright (C) 2023-2025 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 <errno.h>
  20 #include <setjmp.h>
  21 #include <stdbool.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <sys/resource.h>
  25 #include <unistd.h>
  26
  27 #include <support/check.h>
  28 #include <support/support.h>
  29 #include <support/temp_file.h>
  30
  31 jmp_buf chk_fail_buf;
  32 bool chk_fail_ok;
  33
  34 const char *str2 = "F";
  35 char buf2[10] = "%s";
  36
  37 static int
  38 do_test (void)
  39 {
  40   struct rlimit rl;
  41   int max_fd = 24;
  42
  43   if (getrlimit (RLIMIT_NOFILE, &rl) == -1)
  44     FAIL_EXIT1 ("getrlimit (RLIMIT_NOFILE): %m");
  45
  46   max_fd = (rl.rlim_cur < max_fd ? rl.rlim_cur : max_fd);
  47   rl.rlim_cur = max_fd;
  48
  49   if (setrlimit (RLIMIT_NOFILE, &rl) == 1)
  50     FAIL_EXIT1 ("setrlimit (RLIMIT_NOFILE): %m");
  51
  52   /* Exhaust the file descriptor limit with temporary files.  */
  53   int nfiles = 0;
  54   for (; nfiles < max_fd; nfiles++)
  55     {
  56       int fd = create_temp_file ("tst-sprintf-fortify-rdonly-.", NULL);
  57       if (fd == -1)
  58         {
  59           if (errno != EMFILE)
  60             FAIL_EXIT1 ("create_temp_file: %m");
  61           break;
  62         }
  63     }
  64   TEST_VERIFY_EXIT (nfiles != 0);
  65
  66   /* When the format string is writable and contains %n,
  67      with -D_FORTIFY_SOURCE=2 it causes __chk_fail.  However, if libc can not
  68      open procfs to check if the input format string in within a writable
  69      memory segment, the fortify version can not perform the check.  */
  70   char buf[128];
  71   int n1;
  72   int n2;
  73
  74   strcpy (buf2 + 2, "%n%s%n");
  75   if (sprintf (buf, buf2, str2, &n1, str2, &n2) != 2
  76       || n1 != 1 || n2 != 2)
  77     FAIL_EXIT1 ("sprintf failed: %s %d %d", buf, n1, n2);
  78
  79   return 0;
  80 }
  81
  82 #include <support/test-driver.c>