150 lines
4.6 KiB
Diff
150 lines
4.6 KiB
Diff
https://sourceware.org/git/gitweb.cgi?p=glibc.git;a=patch;h=5460617d1567657621107d895ee2dd83bc1f88f2
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with ChangeLog removed
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From 5460617d1567657621107d895ee2dd83bc1f88f2 Mon Sep 17 00:00:00 2001
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From: Paul Pluzhnikov <ppluzhnikov@google.com>
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Date: Tue, 8 May 2018 18:12:41 -0700
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Subject: [PATCH] Fix BZ 22786: integer addition overflow may cause stack
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buffer overflow when realpath() input length is close to SSIZE_MAX.
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2018-05-09 Paul Pluzhnikov <ppluzhnikov@google.com>
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[BZ #22786]
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* stdlib/canonicalize.c (__realpath): Fix overflow in path length
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computation.
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* stdlib/Makefile (test-bz22786): New test.
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* stdlib/test-bz22786.c: New test.
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---
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ChangeLog | 8 +++++
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stdlib/Makefile | 2 +-
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stdlib/canonicalize.c | 2 +-
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stdlib/test-bz22786.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++++++
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4 files changed, 100 insertions(+), 2 deletions(-)
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create mode 100644 stdlib/test-bz22786.c
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diff --git a/stdlib/Makefile b/stdlib/Makefile
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index af1643c..1ddb1f9 100644
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--- a/stdlib/Makefile
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+++ b/stdlib/Makefile
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@@ -84,7 +84,7 @@ tests := tst-strtol tst-strtod testmb testrand testsort testdiv \
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tst-cxa_atexit tst-on_exit test-atexit-race \
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test-at_quick_exit-race test-cxa_atexit-race \
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test-on_exit-race test-dlclose-exit-race \
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- tst-makecontext-align
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+ tst-makecontext-align test-bz22786
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tests-internal := tst-strtod1i tst-strtod3 tst-strtod4 tst-strtod5i \
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tst-tls-atexit tst-tls-atexit-nodelete
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diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c
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index 4135f3f..390fb43 100644
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--- a/stdlib/canonicalize.c
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+++ b/stdlib/canonicalize.c
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@@ -181,7 +181,7 @@ __realpath (const char *name, char *resolved)
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extra_buf = __alloca (path_max);
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len = strlen (end);
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- if ((long int) (n + len) >= path_max)
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+ if (path_max - n <= len)
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{
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__set_errno (ENAMETOOLONG);
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goto error;
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diff --git a/stdlib/test-bz22786.c b/stdlib/test-bz22786.c
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new file mode 100644
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index 0000000..e7837f9
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--- /dev/null
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+++ b/stdlib/test-bz22786.c
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@@ -0,0 +1,90 @@
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+/* 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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+
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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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+
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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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+
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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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+
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+/* This file must be run from within a directory called "stdlib". */
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+
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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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+
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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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+
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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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+
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+ const size_t path_len = (size_t) INT_MAX + 1;
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+
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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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+
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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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+
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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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+
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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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+
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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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+
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+ /* Cleanup. */
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+ unlink (lnk);
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+ rmdir (dir);
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+
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+ return 0;
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+}
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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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--
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2.9.3
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