--- /dev/null
+++ libmalloc/libmalloc-521.100.59/tests/region_cookie_test.c
@@ -0,0 +1,88 @@
+//
+//  region_cookie_test.c
+//  libsystem_malloc
+//
+//  Created by Kim Topley on 10/24/18.
+//
+
+#include <darwintest.h>
+#include <../src/internal.h>
+
+T_GLOBAL_META(T_META_RUN_CONCURRENTLY(true));
+
+T_DECL(tiny_region_cookie_test, "Crash on corruption of tiny region cookie",
+		T_META_ENVVAR("MallocNanoZone=0"),
+		T_META_ENVVAR("MallocMaxMagazines=1"),
+		T_META_IGNORECRASHES("region_cookie_test"))
+{
+	pid_t child_pid = fork();
+	T_ASSERT_NE(child_pid, -1, "Fork failed");
+
+	if (!child_pid) {
+		// MallocMaxMagazines=1 ensures these allocations come from the
+		// same magazine.
+		void *ptr1 = malloc(1);
+		void *ptr2 = malloc(1);
+		T_ASSERT_NOTNULL(ptr1, "Allocation #1 succeeded");
+		T_ASSERT_NOTNULL(ptr2, "Allocation #2 succeeded");
+
+		// Corrupt the region cookie for both pointers (just in case they
+		// are in different regions).
+		void *region = TINY_REGION_FOR_PTR(ptr1);
+		REGION_COOKIE_FOR_TINY_REGION(region)++;
+
+		region = TINY_REGION_FOR_PTR(ptr2);
+		REGION_COOKIE_FOR_TINY_REGION(region)++;
+
+		free(ptr1);
+		free(ptr2);
+
+		// Should not get here
+		T_FAIL("Tiny region cookie corruption test failed");
+	} else {
+		int status;
+		pid_t wait_pid = waitpid(child_pid, &status, 0);
+		T_ASSERT_EQ(wait_pid, child_pid, "Got child status");
+		T_ASSERT_TRUE(WIFSIGNALED(status), "Child terminated by signal");
+		T_ASSERT_EQ(WTERMSIG(status), SIGABRT, "Child aborted");
+	}
+}
+
+T_DECL(small_region_cookie_test, "Crash on corruption of small region cookie",
+		T_META_ENVVAR("MallocNanoZone=0"),
+		T_META_ENVVAR("MallocMaxMagazines=1"),
+		T_META_IGNORECRASHES("region_cookie_test"))
+{
+	pid_t child_pid = fork();
+	T_ASSERT_NE(child_pid, -1, "Fork failed");
+
+	if (!child_pid) {
+		// MallocMaxMagazines=1 ensures these allocations come from the
+		// same magazine.
+		void *ptr1 = malloc(TINY_LIMIT_THRESHOLD + 1);
+		void *ptr2 = malloc(TINY_LIMIT_THRESHOLD + 1);
+		T_ASSERT_NOTNULL(ptr1, "Allocation #1 succeeded");
+		T_ASSERT_NOTNULL(ptr2, "Allocation #2 succeeded");
+
+		// Corrupt the region cookie for both pointers (just in case they
+		// are in different regions).
+		void *region = SMALL_REGION_FOR_PTR(ptr1);
+		REGION_COOKIE_FOR_SMALL_REGION(region)++;
+
+		region = TINY_REGION_FOR_PTR(ptr2);
+		REGION_COOKIE_FOR_SMALL_REGION(region)++;
+
+		free(ptr1);
+		free(ptr2);
+
+		// Should not get here
+		T_FAIL("Small region cookie corruption test failed");
+	} else {
+		int status;
+		pid_t wait_pid = waitpid(child_pid, &status, 0);
+		T_ASSERT_EQ(wait_pid, child_pid, "Got child status");
+		T_ASSERT_TRUE(WIFSIGNALED(status), "Child terminated by signal");
+		T_ASSERT_EQ(WTERMSIG(status), SIGABRT, "Child aborted");
+	}
+}
+