linux/lib/test_kasan_module.c
Andrey Konovalov f16de0bcdb kasan: test: avoid corrupting memory in kasan_rcu_uaf
kasan_rcu_uaf() writes to freed memory via kasan_rcu_reclaim(), which is
only safe with the GENERIC mode (as it uses quarantine).  For other modes,
this test corrupts kernel memory, which might result in a crash.

Turn the write into a read.

Link: https://lkml.kernel.org/r/b6f2c3bf712d2457c783fa59498225b66a634f62.1628779805.git.andreyknvl@gmail.com
Signed-off-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-09-03 09:58:15 -07:00

140 lines
3.3 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <a.ryabinin@samsung.com>
*/
#define pr_fmt(fmt) "kasan test: %s " fmt, __func__
#include <linux/mman.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include "../mm/kasan/kasan.h"
static noinline void __init copy_user_test(void)
{
char *kmem;
char __user *usermem;
size_t size = 128 - KASAN_GRANULE_SIZE;
int __maybe_unused unused;
kmem = kmalloc(size, GFP_KERNEL);
if (!kmem)
return;
usermem = (char __user *)vm_mmap(NULL, 0, PAGE_SIZE,
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_ANONYMOUS | MAP_PRIVATE, 0);
if (IS_ERR(usermem)) {
pr_err("Failed to allocate user memory\n");
kfree(kmem);
return;
}
pr_info("out-of-bounds in copy_from_user()\n");
unused = copy_from_user(kmem, usermem, size + 1);
pr_info("out-of-bounds in copy_to_user()\n");
unused = copy_to_user(usermem, kmem, size + 1);
pr_info("out-of-bounds in __copy_from_user()\n");
unused = __copy_from_user(kmem, usermem, size + 1);
pr_info("out-of-bounds in __copy_to_user()\n");
unused = __copy_to_user(usermem, kmem, size + 1);
pr_info("out-of-bounds in __copy_from_user_inatomic()\n");
unused = __copy_from_user_inatomic(kmem, usermem, size + 1);
pr_info("out-of-bounds in __copy_to_user_inatomic()\n");
unused = __copy_to_user_inatomic(usermem, kmem, size + 1);
pr_info("out-of-bounds in strncpy_from_user()\n");
unused = strncpy_from_user(kmem, usermem, size + 1);
vm_munmap((unsigned long)usermem, PAGE_SIZE);
kfree(kmem);
}
static struct kasan_rcu_info {
int i;
struct rcu_head rcu;
} *global_rcu_ptr;
static noinline void __init kasan_rcu_reclaim(struct rcu_head *rp)
{
struct kasan_rcu_info *fp = container_of(rp,
struct kasan_rcu_info, rcu);
kfree(fp);
((volatile struct kasan_rcu_info *)fp)->i;
}
static noinline void __init kasan_rcu_uaf(void)
{
struct kasan_rcu_info *ptr;
pr_info("use-after-free in kasan_rcu_reclaim\n");
ptr = kmalloc(sizeof(struct kasan_rcu_info), GFP_KERNEL);
if (!ptr) {
pr_err("Allocation failed\n");
return;
}
global_rcu_ptr = rcu_dereference_protected(ptr, NULL);
call_rcu(&global_rcu_ptr->rcu, kasan_rcu_reclaim);
}
static noinline void __init kasan_workqueue_work(struct work_struct *work)
{
kfree(work);
}
static noinline void __init kasan_workqueue_uaf(void)
{
struct workqueue_struct *workqueue;
struct work_struct *work;
workqueue = create_workqueue("kasan_wq_test");
if (!workqueue) {
pr_err("Allocation failed\n");
return;
}
work = kmalloc(sizeof(struct work_struct), GFP_KERNEL);
if (!work) {
pr_err("Allocation failed\n");
return;
}
INIT_WORK(work, kasan_workqueue_work);
queue_work(workqueue, work);
destroy_workqueue(workqueue);
pr_info("use-after-free on workqueue\n");
((volatile struct work_struct *)work)->data;
}
static int __init test_kasan_module_init(void)
{
/*
* Temporarily enable multi-shot mode. Otherwise, KASAN would only
* report the first detected bug and panic the kernel if panic_on_warn
* is enabled.
*/
bool multishot = kasan_save_enable_multi_shot();
copy_user_test();
kasan_rcu_uaf();
kasan_workqueue_uaf();
kasan_restore_multi_shot(multishot);
return -EAGAIN;
}
module_init(test_kasan_module_init);
MODULE_LICENSE("GPL");