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af7519f7b3
Integer addition overflow may cause stack buffer overflow
when realpath() input length is close to SSIZE_MAX.
2018-05-09 Paul Pluzhnikov <ppluzhnikov@google.com>
[BZ #22786]
* stdlib/canonicalize.c (__realpath): Fix overflow in path length
computation.
* stdlib/Makefile (test-bz22786): New test.
* stdlib/test-bz22786.c: New test.
(cherry picked from commit 5460617d15)
91 lines
2.5 KiB
C
91 lines
2.5 KiB
C
/* Bug 22786: test for buffer overflow in realpath.
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Copyright (C) 2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* This file must be run from within a directory called "stdlib". */
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#include <errno.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <support/test-driver.h>
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#include <libc-diag.h>
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static int
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do_test (void)
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{
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const char dir[] = "bz22786";
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const char lnk[] = "bz22786/symlink";
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rmdir (dir);
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if (mkdir (dir, 0755) != 0 && errno != EEXIST)
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{
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printf ("mkdir %s: %m\n", dir);
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return EXIT_FAILURE;
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}
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if (symlink (".", lnk) != 0 && errno != EEXIST)
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{
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printf ("symlink (%s, %s): %m\n", dir, lnk);
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return EXIT_FAILURE;
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}
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const size_t path_len = (size_t) INT_MAX + 1;
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DIAG_PUSH_NEEDS_COMMENT;
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#if __GNUC_PREREQ (7, 0)
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/* GCC 7 warns about too-large allocations; here we need such
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allocation to succeed for the test to work. */
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DIAG_IGNORE_NEEDS_COMMENT (7, "-Walloc-size-larger-than=");
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#endif
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char *path = malloc (path_len);
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DIAG_POP_NEEDS_COMMENT;
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if (path == NULL)
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{
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printf ("malloc (%zu): %m\n", path_len);
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return EXIT_UNSUPPORTED;
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}
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/* Construct very long path = "bz22786/symlink/aaaa....." */
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char *p = mempcpy (path, lnk, sizeof (lnk) - 1);
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*(p++) = '/';
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memset (p, 'a', path_len - (path - p) - 2);
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p[path_len - (path - p) - 1] = '\0';
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/* This call crashes before the fix for bz22786 on 32-bit platforms. */
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p = realpath (path, NULL);
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if (p != NULL || errno != ENAMETOOLONG)
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{
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printf ("realpath: %s (%m)", p);
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return EXIT_FAILURE;
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}
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/* Cleanup. */
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unlink (lnk);
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rmdir (dir);
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return 0;
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}
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#define TEST_FUNCTION do_test
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#include <support/test-driver.c>
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