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Subject[RFC/PATCH v2 10/10] lib: add kasan test module
Date
This is a test module doing varios nasty things like
out of bounds accesses, use after free. It is usefull 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>
---
lib/Kconfig.debug | 8 ++
lib/Makefile | 1 +
lib/test_kasan.c | 254 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 263 insertions(+)
create mode 100644 lib/test_kasan.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 09824b5..d3190bb 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -633,6 +633,14 @@ config DEBUG_STACKOVERFLOW

If in doubt, say "N".

+config TEST_KASAN
+ tristate "Module for testing kasan for bug detection"
+ depends on m
+ help
+ This is a test module doing varios nasty things like
+ out of bounds accesses, use after free. It is usefull for testing
+ kernel debugging features like kernel address sanitizer.
+
source "lib/Kconfig.kmemcheck"

source "lib/Kconfig.kasan"
diff --git a/lib/Makefile b/lib/Makefile
index b73c3c3..4da59a9 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -35,6 +35,7 @@ obj-$(CONFIG_TEST_MODULE) += test_module.o
obj-$(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

ifeq ($(CONFIG_DEBUG_KOBJECT),y)
CFLAGS_kobject.o += -DDEBUG
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
new file mode 100644
index 0000000..e448d4e
--- /dev/null
+++ b/lib/test_kasan.c
@@ -0,0 +1,254 @@
+/*
+ *
+ * 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>
+
+void __init kmalloc_oob_rigth(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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+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';
+}
+
+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);
+}
+
+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);
+}
+
+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);
+}
+
+int __init kmalloc_tests_init(void)
+{
+ kmalloc_oob_rigth();
+ 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();
+ return -EAGAIN;
+}
+
+module_init(kmalloc_tests_init);
+MODULE_LICENSE("GPL");
--
1.8.5.5


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