debug/tst-sprintf-fortify-unchecked.c

   1 /* Tests for fortified sprintf with unknown buffer bounds (bug 30039).
   2    Copyright (C) 2023 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 <printf.h>
  20 #include <stdarg.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <support/check.h>
  24
  25 /* This test is not built with _FORTIFY_SOURCE.  Instead it calls the
  26    appropriate implementation directly.  The fortify mode is specified
  27    in this variable.  */
  28 static int fortify_mode;
  29
  30 /* This does not handle long-double redirects etc., but we test only
  31    format strings that stay within the confines of the base
  32    implementation.  */
  33 int __vsprintf_chk (char *s, int flag, size_t slen, const char *format,
  34                     va_list ap);
  35
  36 /* Invoke vsprintf or __vsprintf_chk according to fortify_mode.  */
  37 static int
  38 my_vsprintf (char *buf, const char *format, va_list ap)
  39 {
  40   int result;
  41   if (fortify_mode == 0)
  42     result = vsprintf (buf, format, ap);
  43   else
  44     /* Call the fortified version with an unspecified length.  */
  45     result = __vsprintf_chk (buf, fortify_mode - 1, -1, format, ap);
  46   return result;
  47 }
  48
  49 /* Run one test, with the specified expected output.  */
  50 static void __attribute ((format (printf, 2, 3)))
  51 do_check (const char *expected, const char *format, ...)
  52 {
  53   va_list ap;
  54   va_start (ap, format);
  55
  56   char buf_expected[24];
  57   memset (buf_expected, '@', sizeof (buf_expected));
  58   TEST_VERIFY (strlen (expected) < sizeof (buf_expected));
  59   strcpy (buf_expected, expected);
  60
  61   char buf[sizeof (buf_expected)];
  62   memset (buf, '@', sizeof (buf));
  63
  64   int ret = my_vsprintf (buf, format, ap);
  65   TEST_COMPARE_BLOB (buf_expected, sizeof (buf_expected), buf, sizeof (buf));
  66   TEST_COMPARE (ret, strlen (expected));
  67
  68   va_end (ap);
  69 }
  70
  71 /* Run the tests in all fortify modes.  */
  72 static void
  73 do_tests (void)
  74 {
  75   for (fortify_mode = 0; fortify_mode <= 3; ++fortify_mode)
  76     {
  77       do_check ("0", "%d", 0);
  78       do_check ("-2147483648", "%d", -2147483647 - 1);
  79       do_check ("-9223372036854775808", "%lld", -9223372036854775807LL - 1);
  80       do_check ("", "%s", "");
  81       do_check ("                      ", "%22s", "");
  82       do_check ("XXXXXXXXXXXXXXXXXXXXXX", "%s", "XXXXXXXXXXXXXXXXXXXXXX");
  83       do_check ("1.125000", "%f", 1.125);
  84       do_check ("1.125", "%g", 1.125);
  85       do_check ("1.125", "%.8g", 1.125);
  86     }
  87 }
  88
  89 /* printf callback that falls back to the glibc-supplied
  90    implementation.  */
  91 static int
  92 dummy_printf_function (FILE *__stream,
  93                        const struct printf_info *__info,
  94                        const void *const *__args)
  95 {
  96   return -2;                    /* Request fallback.  */
  97 }
  98
  99 /* Likewise for the type information.  */
 100 static int
 101 dummy_arginfo_function (const struct printf_info *info,
 102                         size_t n, int *argtypes, int *size)
 103 {
 104   return -1;                    /* Request fallback.  */
 105 }
 106
 107 static int
 108 do_test (void)
 109 {
 110   do_tests ();
 111
 112   /* Activate __printf_function_invoke mode.  */
 113   register_printf_specifier ('d', dummy_printf_function,
 114                              dummy_arginfo_function);
 115   register_printf_specifier ('g', dummy_printf_function,
 116                              dummy_arginfo_function);
 117   register_printf_specifier ('s', dummy_printf_function,
 118                              dummy_arginfo_function);
 119
 120   /* Rerun the tests with callback functions.  */
 121   do_tests ();
 122
 123   return 0;
 124 }
 125
 126 #include <support/test-driver.c>