Libc-1353.100.2.tar.gz

[apple/libc.git] / secure / chk_fail.c

diff --git a/secure/chk_fail.c b/secure/chk_fail.c
index 29401b886dafaff4fc867ee335f3a5a9b9e852dd..9dc6c002f0a82a6929ad307bc81a01f530724e23 100644 (file)
--- a/secure/chk_fail.c
+++ b/secure/chk_fail.c
@@ -21,10 +21,91 @@
  * @APPLE_LICENSE_HEADER_END@
  */
 
-#include <syslog.h>
-#include <sys/sysctl.h>
-#include <sys/param.h>
-#include <unistd.h>
-#include <stdlib.h>
+#include <os/assumes.h>
+#include <stdint.h>
 #include <TargetConditionals.h>
+#include "crt_externs.h"
 
+#ifndef PR_13085474_CHECK
+#define PR_13085474_CHECK TARGET_OS_OSX
+#endif
+
+#if PR_13085474_CHECK
+/* 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>
+#if TARGET_OS_OSX
+#define START_VERSION dyld_platform_version_macOS_10_9
+#else
+#error "This platform should not build with PR_13085474_CHECK=1"
+#endif
+#endif /* !PR_13085474_CHECK */
+
+/* For PR_13085474_CHECK set, we initialize __chk_assert_no_overlap to
+ * 1 initially and then reset it to 0 if the main image of the process
+ * was linked earlier than 10.9.
+ *
+ * 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 = 1;
+
+#if PR_13085474_CHECK
+static bool
+__chk_assert_sdk_pre_start(const struct mach_header *mh) {
+  return (dyld_get_active_platform() == PLATFORM_MACOS &&
+      !dyld_sdk_at_least(mh, START_VERSION));
+}
+#endif
+
+__attribute__ ((visibility ("hidden")))
+void __chk_init(void) {
+#if PR_13085474_CHECK
+  if (__chk_assert_sdk_pre_start((const struct mach_header *)
+        _NSGetMachExecuteHeader())) {
+    __chk_assert_no_overlap = 0;
+  }
+#endif
+}
+
+__attribute__ ((visibility ("hidden")))
+__attribute__ ((noreturn))
+void
+__chk_fail_overflow (void) {
+  os_crash("detected buffer overflow");
+}
+
+__attribute__ ((visibility ("hidden")))
+__attribute__ ((noreturn))
+void
+__chk_fail_overlap (void) {
+  os_crash("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();
+  }
+}