lib: add kasan test module

This is a test module doing various nasty things like out of bounds
accesses, use after free.  It is useful for testing kernel debugging
features like kernel address sanitizer.

It mostly concentrates on testing of slab allocator, but we might want to
add more different stuff here in future (like stack/global variables out
of bounds accesses and so on).

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: Andrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/Kconfig.kasan

@@ -42,4 +42,12 @@ config KASAN_INLINE
 
 endchoice
 
+config TEST_KASAN
+	tristate "Module for testing kasan for bug detection"
+	depends on m && KASAN
+	help
+	  This is a test module doing various nasty things like
+	  out of bounds accesses, use after free. It is useful for testing
+	  kernel debugging features like kernel address sanitizer.
+
 endif

lib/Makefile

@@ -32,12 +32,13 @@ obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
 obj-y += hexdump.o
 obj-$(CONFIG_TEST_HEXDUMP) += test-hexdump.o
 obj-y += kstrtox.o
-obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
-obj-$(CONFIG_TEST_LKM) += test_module.o
-obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
 obj-$(CONFIG_TEST_BPF) += test_bpf.o
 obj-$(CONFIG_TEST_FIRMWARE) += test_firmware.o
+obj-$(CONFIG_TEST_KASAN) += test_kasan.o
+obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o
+obj-$(CONFIG_TEST_LKM) += test_module.o
 obj-$(CONFIG_TEST_RHASHTABLE) += test_rhashtable.o
+obj-$(CONFIG_TEST_USER_COPY) += test_user_copy.o
 
 ifeq ($(CONFIG_DEBUG_KOBJECT),y)
 CFLAGS_kobject.o += -DDEBUG

lib/test_kasan.c

@@ -0,0 +1,277 @@
+/*
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <a.ryabinin@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt) "kasan test: %s " fmt, __func__
+
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/module.h>
+
+static noinline void __init kmalloc_oob_right(void)
+{
+	char *ptr;
+	size_t size = 123;
+
+	pr_info("out-of-bounds to right\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	ptr[size] = 'x';
+	kfree(ptr);
+}
+
+static noinline void __init kmalloc_oob_left(void)
+{
+	char *ptr;
+	size_t size = 15;
+
+	pr_info("out-of-bounds to left\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	*ptr = *(ptr - 1);
+	kfree(ptr);
+}
+
+static noinline void __init kmalloc_node_oob_right(void)
+{
+	char *ptr;
+	size_t size = 4096;
+
+	pr_info("kmalloc_node(): out-of-bounds to right\n");
+	ptr = kmalloc_node(size, GFP_KERNEL, 0);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	ptr[size] = 0;
+	kfree(ptr);
+}
+
+static noinline void __init kmalloc_large_oob_rigth(void)
+{
+	char *ptr;
+	size_t size = KMALLOC_MAX_CACHE_SIZE + 10;
+
+	pr_info("kmalloc large allocation: out-of-bounds to right\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	ptr[size] = 0;
+	kfree(ptr);
+}
+
+static noinline void __init kmalloc_oob_krealloc_more(void)
+{
+	char *ptr1, *ptr2;
+	size_t size1 = 17;
+	size_t size2 = 19;
+
+	pr_info("out-of-bounds after krealloc more\n");
+	ptr1 = kmalloc(size1, GFP_KERNEL);
+	ptr2 = krealloc(ptr1, size2, GFP_KERNEL);
+	if (!ptr1 || !ptr2) {
+		pr_err("Allocation failed\n");
+		kfree(ptr1);
+		return;
+	}
+
+	ptr2[size2] = 'x';
+	kfree(ptr2);
+}
+
+static noinline void __init kmalloc_oob_krealloc_less(void)
+{
+	char *ptr1, *ptr2;
+	size_t size1 = 17;
+	size_t size2 = 15;
+
+	pr_info("out-of-bounds after krealloc less\n");
+	ptr1 = kmalloc(size1, GFP_KERNEL);
+	ptr2 = krealloc(ptr1, size2, GFP_KERNEL);
+	if (!ptr1 || !ptr2) {
+		pr_err("Allocation failed\n");
+		kfree(ptr1);
+		return;
+	}
+	ptr2[size1] = 'x';
+	kfree(ptr2);
+}
+
+static noinline void __init kmalloc_oob_16(void)
+{
+	struct {
+		u64 words[2];
+	} *ptr1, *ptr2;
+
+	pr_info("kmalloc out-of-bounds for 16-bytes access\n");
+	ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL);
+	ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL);
+	if (!ptr1 || !ptr2) {
+		pr_err("Allocation failed\n");
+		kfree(ptr1);
+		kfree(ptr2);
+		return;
+	}
+	*ptr1 = *ptr2;
+	kfree(ptr1);
+	kfree(ptr2);
+}
+
+static noinline void __init kmalloc_oob_in_memset(void)
+{
+	char *ptr;
+	size_t size = 666;
+
+	pr_info("out-of-bounds in memset\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	memset(ptr, 0, size+5);
+	kfree(ptr);
+}
+
+static noinline void __init kmalloc_uaf(void)
+{
+	char *ptr;
+	size_t size = 10;
+
+	pr_info("use-after-free\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	kfree(ptr);
+	*(ptr + 8) = 'x';
+}
+
+static noinline void __init kmalloc_uaf_memset(void)
+{
+	char *ptr;
+	size_t size = 33;
+
+	pr_info("use-after-free in memset\n");
+	ptr = kmalloc(size, GFP_KERNEL);
+	if (!ptr) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	kfree(ptr);
+	memset(ptr, 0, size);
+}
+
+static noinline void __init kmalloc_uaf2(void)
+{
+	char *ptr1, *ptr2;
+	size_t size = 43;
+
+	pr_info("use-after-free after another kmalloc\n");
+	ptr1 = kmalloc(size, GFP_KERNEL);
+	if (!ptr1) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	kfree(ptr1);
+	ptr2 = kmalloc(size, GFP_KERNEL);
+	if (!ptr2) {
+		pr_err("Allocation failed\n");
+		return;
+	}
+
+	ptr1[40] = 'x';
+	kfree(ptr2);
+}
+
+static noinline void __init kmem_cache_oob(void)
+{
+	char *p;
+	size_t size = 200;
+	struct kmem_cache *cache = kmem_cache_create("test_cache",
+						size, 0,
+						0, NULL);
+	if (!cache) {
+		pr_err("Cache allocation failed\n");
+		return;
+	}
+	pr_info("out-of-bounds in kmem_cache_alloc\n");
+	p = kmem_cache_alloc(cache, GFP_KERNEL);
+	if (!p) {
+		pr_err("Allocation failed\n");
+		kmem_cache_destroy(cache);
+		return;
+	}
+
+	*p = p[size];
+	kmem_cache_free(cache, p);
+	kmem_cache_destroy(cache);
+}
+
+static char global_array[10];
+
+static noinline void __init kasan_global_oob(void)
+{
+	volatile int i = 3;
+	char *p = &global_array[ARRAY_SIZE(global_array) + i];
+
+	pr_info("out-of-bounds global variable\n");
+	*(volatile char *)p;
+}
+
+static noinline void __init kasan_stack_oob(void)
+{
+	char stack_array[10];
+	volatile int i = 0;
+	char *p = &stack_array[ARRAY_SIZE(stack_array) + i];
+
+	pr_info("out-of-bounds on stack\n");
+	*(volatile char *)p;
+}
+
+static int __init kmalloc_tests_init(void)
+{
+	kmalloc_oob_right();
+	kmalloc_oob_left();
+	kmalloc_node_oob_right();
+	kmalloc_large_oob_rigth();
+	kmalloc_oob_krealloc_more();
+	kmalloc_oob_krealloc_less();
+	kmalloc_oob_16();
+	kmalloc_oob_in_memset();
+	kmalloc_uaf();
+	kmalloc_uaf_memset();
+	kmalloc_uaf2();
+	kmem_cache_oob();
+	kasan_stack_oob();
+	kasan_global_oob();
+	return -EAGAIN;
+}
+
+module_init(kmalloc_tests_init);
+MODULE_LICENSE("GPL");