Free Electrons

Embedded Linux Experts

/*
 *
 * 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");