/* * Copyright (c) 2007-2013 Apple Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this * file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_LICENSE_HEADER_END@ */ #include <syslog.h> #include <sys/sysctl.h> #include <sys/param.h> #include <unistd.h> #include <stdlib.h> #include <TargetConditionals.h> #if !defined(PR_13085474_CHECK) #define PR_13085474_CHECK 1 /* Some shipped applications fail this check and were tested against * versions of these functions that supported overlapping buffers. * * We would rather let such applications run, using the old memmove * implementation, than abort() because they can't use the new * implementation. */ #include <libkern/OSAtomic.h> #include <mach-o/dyld.h> #include <mach-o/dyld_priv.h> #define DYLD_OS_VERSION(major, minor, tiny) ((((major) & 0xffff) << 16) | (((minor) & 0xff) << 8) | ((tiny) & 0xff)) #if TARGET_OS_IPHONE #define START_VERSION DYLD_OS_VERSION(7,0,0) #else #define START_VERSION DYLD_OS_VERSION(10,9,0) #endif #endif /* !PR_13085474_CHECK */ /* For PR_13085474_CHECK set, we initialize __chk_assert_no_overlap to * a value neither 0 or 1. We call _dyld_register_func_for_add_image() * to register a callback, and use the non-one value of * __chk_assert_no_overlap to skip sdk version checks (but we do * perform overlap checks). To detect if the main program was built * prior to START_VERSION, we call dyld_get_program_sdk_version(), * which we do before setting up the callback (since we don't need it * if the main program is older). * * After _dyld_register_func_for_add_image() returns, we set * __chk_assert_no_overlap to 1, which enables the sdk version checking * for subsequent loaded shared objects. If we then find an old version, * we set __chk_assert_no_overlap to 0 to turn off overlap checking. * * If PR_13085474_CHECK is zero, then we never do any sdk version checking * and always do overlap checks. */ __attribute__ ((visibility ("hidden"))) uint32_t __chk_assert_no_overlap #if PR_13085474_CHECK = 42; #else = 1; #endif #if PR_13085474_CHECK static void __chk_assert_no_overlap_callback(const struct mach_header *mh, intptr_t vmaddr_slide __unused) { if (__chk_assert_no_overlap != 1) return; if (dyld_get_sdk_version(mh) < START_VERSION) OSAtomicAnd32(0U, &__chk_assert_no_overlap); } #endif __attribute__ ((visibility ("hidden"))) void __chk_init(void) { #if PR_13085474_CHECK if (dyld_get_program_sdk_version() < START_VERSION) { __chk_assert_no_overlap = 0; } else { _dyld_register_func_for_add_image(__chk_assert_no_overlap_callback); __chk_assert_no_overlap = 1; } #endif } __attribute__ ((noreturn)) static void __chk_fail (const char *message) { syslog(LOG_CRIT, "%s", message); abort_report_np("%s", message); } __attribute__ ((visibility ("hidden"))) __attribute__ ((noreturn)) void __chk_fail_overflow (void) { __chk_fail("detected buffer overflow"); } __attribute__ ((visibility ("hidden"))) __attribute__ ((noreturn)) void __chk_fail_overlap (void) { __chk_fail("detected source and destination buffer overlap"); } __attribute__ ((visibility ("hidden"))) void __chk_overlap (const void *_a, size_t an, const void *_b, size_t bn) { uintptr_t a = (uintptr_t)_a; uintptr_t b = (uintptr_t)_b; if (__builtin_expect(an == 0 || bn == 0, 0)) { return; } else if (__builtin_expect(a == b, 0)) { __chk_fail_overlap(); } else if (a < b) { if (__builtin_expect(a + an > b, 0)) __chk_fail_overlap(); } else { // b < a if (__builtin_expect(b + bn > a, 0)) __chk_fail_overlap(); } }