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author | Siddhesh Poyarekar <siddhesh@sourceware.org> | 2022-01-13 11:28:36 +0530 |
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committer | Siddhesh Poyarekar <siddhesh@sourceware.org> | 2022-01-21 23:01:30 +0530 |
commit | ee8d5e33adb284601c00c94687bc907e10aec9bb (patch) | |
tree | c1e3b5584266640b915abcbd151032935b9695fb /stdlib | |
parent | fb7bff12e81c677a6622f724edd4d4987dd9d971 (diff) | |
download | glibc-ee8d5e33adb284601c00c94687bc907e10aec9bb.zip glibc-ee8d5e33adb284601c00c94687bc907e10aec9bb.tar.gz glibc-ee8d5e33adb284601c00c94687bc907e10aec9bb.tar.bz2 |
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>
Diffstat (limited to 'stdlib')
-rw-r--r-- | stdlib/Makefile | 1 | ||||
-rw-r--r-- | stdlib/canonicalize.c | 12 | ||||
-rw-r--r-- | stdlib/tst-realpath-toolong.c | 49 |
3 files changed, 60 insertions, 2 deletions
diff --git a/stdlib/Makefile b/stdlib/Makefile index 1e81f98..8236741 100644 --- a/stdlib/Makefile +++ b/stdlib/Makefile @@ -109,6 +109,7 @@ tests := \ tst-random \ tst-random2 \ tst-realpath \ + tst-realpath-toolong \ tst-secure-getenv \ tst-setcontext \ tst-setcontext2 \ diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c index f36bdf4..732dc7e 100644 --- a/stdlib/canonicalize.c +++ b/stdlib/canonicalize.c @@ -400,8 +400,16 @@ realpath_stk (const char *name, char *resolved, error: *dest++ = '\0'; - if (resolved != NULL && dest - rname <= get_path_max ()) - rname = strcpy (resolved, rname); + if (resolved != NULL) + { + if (dest - rname <= get_path_max ()) + rname = strcpy (resolved, rname); + else + { + failed = true; + __set_errno (ENAMETOOLONG); + } + } error_nomem: scratch_buffer_free (&extra_buffer); diff --git a/stdlib/tst-realpath-toolong.c b/stdlib/tst-realpath-toolong.c new file mode 100644 index 0000000..8bed772 --- /dev/null +++ b/stdlib/tst-realpath-toolong.c @@ -0,0 +1,49 @@ +/* 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/>. */ + +#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> + +#define BASENAME "tst-realpath-toolong." + +int +do_test (void) +{ + char *base = support_create_and_chdir_toolong_temp_directory (BASENAME); + + char buf[PATH_MAX + 1]; + const char *res = realpath (".", buf); + + /* 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); + + free (base); + return 0; +} + +#include <support/test-driver.c> |