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realpath: Set errno to ENAMETOOLONG for result larger than PATH_MAX […
…BZ #28770] realpath returns an allocated string when the result exceeds PATH_MAX, which is unexpected when its second argument is not NULL. This results in the second argument (resolved) being uninitialized and also results in a memory leak since the caller expects resolved to be the same as the returned value. Return NULL and set errno to ENAMETOOLONG if the result exceeds PATH_MAX. This fixes [BZ #28770], which is CVE-2021-3998. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
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/* Verify that realpath returns NULL with ENAMETOOLONG if the result exceeds | ||
NAME_MAX. | ||
Copyright The GNU Toolchain Authors. | ||
This file is part of the GNU C Library. | ||
The GNU C Library is free software; you can redistribute it and/or | ||
modify it under the terms of the GNU Lesser General Public | ||
License as published by the Free Software Foundation; either | ||
version 2.1 of the License, or (at your option) any later version. | ||
The GNU C Library is distributed in the hope that it will be useful, | ||
but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
Lesser General Public License for more details. | ||
You should have received a copy of the GNU Lesser General Public | ||
License along with the GNU C Library; if not, see | ||
<https://www.gnu.org/licenses/>. */ | ||
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#include <errno.h> | ||
#include <limits.h> | ||
#include <stdlib.h> | ||
#include <string.h> | ||
#include <unistd.h> | ||
#include <support/check.h> | ||
#include <support/temp_file.h> | ||
#include <sys/types.h> | ||
#include <sys/stat.h> | ||
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#define BASENAME "tst-realpath-toolong." | ||
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int | ||
do_test (void) | ||
{ | ||
char *base = support_create_and_chdir_toolong_temp_directory (BASENAME); | ||
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char buf[PATH_MAX + 1]; | ||
const char *res = realpath (".", buf); | ||
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/* canonicalize.c states that if the real path is >= PATH_MAX, then | ||
realpath returns NULL and sets ENAMETOOLONG. */ | ||
TEST_VERIFY (res == NULL); | ||
TEST_VERIFY (errno == ENAMETOOLONG); | ||
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free (base); | ||
return 0; | ||
} | ||
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#include <support/test-driver.c> |