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137 lines
4.2 KiB
137 lines
4.2 KiB
commit 5460617d1567657621107d895ee2dd83bc1f88f2 |
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Author: Paul Pluzhnikov <ppluzhnikov@google.com> |
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Date: Tue May 8 18:12:41 2018 -0700 |
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Fix BZ 22786: integer addition overflow may cause stack buffer overflow |
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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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diff --git a/stdlib/Makefile b/stdlib/Makefile |
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index b5553eafc2a4bbd5..7265b44a5082b991 100644 |
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--- a/stdlib/Makefile |
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+++ b/stdlib/Makefile |
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@@ -72,7 +72,7 @@ tests := tst-strtol tst-strtod testmb testrand testsort testdiv \ |
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tst-makecontext3 bug-getcontext bug-fmtmsg1 \ |
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tst-secure-getenv tst-strtod-overflow tst-strtod-round \ |
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tst-tininess tst-strtod-underflow tst-strfmon_l \ |
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- tst-makecontext-align |
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+ tst-makecontext-align test-bz22786 |
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tests-static := tst-secure-getenv |
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include ../Makeconfig |
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diff --git a/stdlib/canonicalize.c b/stdlib/canonicalize.c |
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index aeff804c108de277..b43f6223b98a578a 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 0000000000000000..e7837f98c19fc4bf |
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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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