diff options
| -rw-r--r-- | ChangeLog | 9 | ||||
| -rw-r--r-- | NEWS | 4 | ||||
| -rw-r--r-- | io/Makefile | 2 | ||||
| -rw-r--r-- | io/tst-getcwd-abspath.c | 66 | ||||
| -rw-r--r-- | sysdeps/unix/sysv/linux/getcwd.c | 8 |
5 files changed, 84 insertions, 5 deletions
@@ -1,3 +1,12 @@ +2018-01-12 Dmitry V. Levin <ldv@altlinux.org> + + [BZ #22679] + CVE-2018-1000001 + * sysdeps/unix/sysv/linux/getcwd.c (__getcwd): Fall back to + generic_getcwd if the path returned by getcwd syscall is not absolute. + * io/tst-getcwd-abspath.c: New test. + * io/Makefile (tests): Add tst-getcwd-abspath. + 2018-01-12 Istvan Kurucsai <pistukem@gmail.com> * malloc/malloc.c (malloc_consolidate): Add size check. @@ -199,6 +199,10 @@ Security related changes: for AT_SECURE or SUID binaries could be used to load libraries from the current directory. + CVE-2018-1000001: Buffer underflow in realpath function when getcwd function + succeeds without returning an absolute path due to unexpected behaviour + of the Linux kernel getcwd syscall. Reported by halfdog. + The following bugs are resolved with this release: [The release manager will add the list generated by diff --git a/io/Makefile b/io/Makefile index 09b4f468b0..2117cb6b62 100644 --- a/io/Makefile +++ b/io/Makefile @@ -71,7 +71,7 @@ tests := test-utime test-stat test-stat2 test-lfs tst-getcwd \ tst-mknodat tst-mkfifoat tst-ttyname_r bug-ftw5 \ tst-posix_fallocate tst-posix_fallocate64 \ tst-fts tst-fts-lfs tst-open-tmpfile \ - tst-copy_file_range \ + tst-copy_file_range tst-getcwd-abspath \ # This test includes the compat implementation of copy_file_range, # which uses internal, unexported libc functions. diff --git a/io/tst-getcwd-abspath.c b/io/tst-getcwd-abspath.c new file mode 100644 index 0000000000..3a3636f2ed --- /dev/null +++ b/io/tst-getcwd-abspath.c @@ -0,0 +1,66 @@ +/* BZ #22679 getcwd(3) should not succeed without returning an absolute path. + + Copyright (C) 2018 Free Software Foundation, Inc. + 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 <stdio.h> +#include <stdlib.h> +#include <support/check.h> +#include <support/namespace.h> +#include <support/support.h> +#include <support/temp_file.h> +#include <support/test-driver.h> +#include <support/xunistd.h> +#include <unistd.h> + +static char *chroot_dir; + +/* The actual test. Run it in a subprocess, so that the test harness + can remove the temporary directory in --direct mode. */ +static void +getcwd_callback (void *closure) +{ + xchroot (chroot_dir); + + errno = 0; + char *cwd = getcwd (NULL, 0); + TEST_COMPARE (errno, ENOENT); + TEST_VERIFY (cwd == NULL); + + errno = 0; + cwd = realpath (".", NULL); + TEST_COMPARE (errno, ENOENT); + TEST_VERIFY (cwd == NULL); + + _exit (0); +} + +static int +do_test (void) +{ + support_become_root (); + if (!support_can_chroot ()) + return EXIT_UNSUPPORTED; + + chroot_dir = support_create_temp_directory ("tst-getcwd-abspath-"); + support_isolate_in_subprocess (getcwd_callback, NULL); + + return 0; +} + +#include <support/test-driver.c> diff --git a/sysdeps/unix/sysv/linux/getcwd.c b/sysdeps/unix/sysv/linux/getcwd.c index f545106289..866b9d26d5 100644 --- a/sysdeps/unix/sysv/linux/getcwd.c +++ b/sysdeps/unix/sysv/linux/getcwd.c @@ -76,7 +76,7 @@ __getcwd (char *buf, size_t size) int retval; retval = INLINE_SYSCALL (getcwd, 2, path, alloc_size); - if (retval >= 0) + if (retval > 0 && path[0] == '/') { #ifndef NO_ALLOCATION if (buf == NULL && size == 0) @@ -92,10 +92,10 @@ __getcwd (char *buf, size_t size) return buf; } - /* The system call cannot handle paths longer than a page. - Neither can the magic symlink in /proc/self. Just use the + /* The system call either cannot handle paths longer than a page + or can succeed without returning an absolute path. Just use the generic implementation right away. */ - if (errno == ENAMETOOLONG) + if (retval >= 0 || errno == ENAMETOOLONG) { #ifndef NO_ALLOCATION if (buf == NULL && size == 0) |