1/* Tests for fortified sprintf with unknown buffer bounds (bug 30039).
2 Copyright (C) 2023-2024 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 <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. */
28static 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. */
33int __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. */
37static int
38my_vsprintf (char *buf, const char *format, va_list ap)
39{
40 int result;
41 if (fortify_mode == 0)
42 result = vsprintf (s: buf, format: format, arg: ap);
43 else
44 /* Call the fortified version with an unspecified length. */
45 result = __vsprintf_chk (s: buf, flag: fortify_mode - 1, slen: -1, format, ap);
46 return result;
47}
48
49/* Run one test, with the specified expected output. */
50static void __attribute ((format (printf, 2, 3)))
51do_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. */
72static void
73do_tests (void)
74{
75 for (fortify_mode = 0; fortify_mode <= 3; ++fortify_mode)
76 {
77 do_check (expected: "0", format: "%d", 0);
78 do_check (expected: "-2147483648", format: "%d", -2147483647 - 1);
79 do_check (expected: "-9223372036854775808", format: "%lld", -9223372036854775807LL - 1);
80 do_check (expected: "", format: "%s", "");
81 do_check (expected: " ", format: "%22s", "");
82 do_check (expected: "XXXXXXXXXXXXXXXXXXXXXX", format: "%s", "XXXXXXXXXXXXXXXXXXXXXX");
83 do_check (expected: "1.125000", format: "%f", 1.125);
84 do_check (expected: "1.125", format: "%g", 1.125);
85 do_check (expected: "1.125", format: "%.8g", 1.125);
86 }
87}
88
89/* printf callback that falls back to the glibc-supplied
90 implementation. */
91static int
92dummy_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. */
100static int
101dummy_arginfo_function (const struct printf_info *info,
102 size_t n, int *argtypes, int *size)
103{
104 return -1; /* Request fallback. */
105}
106
107static int
108do_test (void)
109{
110 do_tests ();
111
112 /* Activate __printf_function_invoke mode. */
113 register_printf_specifier (spec: 'd', func: dummy_printf_function,
114 arginfo: dummy_arginfo_function);
115 register_printf_specifier (spec: 'g', func: dummy_printf_function,
116 arginfo: dummy_arginfo_function);
117 register_printf_specifier (spec: 's', func: dummy_printf_function,
118 arginfo: 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>
127

source code of glibc/debug/tst-sprintf-fortify-unchecked.c