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
27static int
28format_failed (const char *fmt, const char *expected)
29{
30 char output[80];
31
32 printf (format: "%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 (format: "FAIL (output '%s' != expected '%s')\n", output, expected);
40 return 1;
41 }
42 puts (s: "ok");
43 return 0;
44}
45
46static int
47do_test (void)
48{
49 int rc = 0;
50 char buf[64];
51
52 /* Regular positionals work. */
53 if (format_failed (fmt: "%1$d", expected: "1") != 0)
54 rc = 1;
55
56 /* Regular width positionals work. */
57 if (format_failed (fmt: "%1$*2$d", expected: " 1") != 0)
58 rc = 1;
59
60 /* Positional arguments are constructed via read_int, so nargs can only
61 overflow on 32-bit systems. On 64-bit systems, it will attempt to
62 allocate a giant amount of memory and possibly crash, which is the
63 expected situation. Since the 64-bit behavior is arch-specific, only
64 test this on 32-bit systems. */
65 if (sizeof (long int) == 4)
66 {
67 sprintf (buf, "%%1$d %%%" PRIdPTR "$d",
68 (intptr_t) (UINT32_MAX / sizeof (int)));
69 if (format_failed (fmt: buf, expected: "1 %$d") != 0)
70 rc = 1;
71 }
72
73 return rc;
74}
75
76#define TEST_FUNCTION do_test ()
77#include "../test-skeleton.c"
78

source code of glibc/stdio-common/bug-vfprintf-nargs.c