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![Kees Cook](/assets/img/avatar_default.png)
Intentional overflows, as performed by the KASAN tests, are detected at compile time[1] (instead of only at run-time) with the addition of __alloc_size. Fix this by forcing the compiler into not being able to trust the size used following the kmalloc()s. [1] https://lore.kernel.org/lkml/20211005184717.65c6d8eb39350395e387b71f@linux-foundation.org Link: https://lkml.kernel.org/r/20211006181544.1670992-1-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.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>
141 lines
3.3 KiB
C
141 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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*
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* Copyright (c) 2014 Samsung Electronics Co., Ltd.
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* Author: Andrey Ryabinin <a.ryabinin@samsung.com>
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*/
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#define pr_fmt(fmt) "kasan test: %s " fmt, __func__
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#include <linux/mman.h>
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#include <linux/module.h>
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#include <linux/printk.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include "../mm/kasan/kasan.h"
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static noinline void __init copy_user_test(void)
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{
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char *kmem;
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char __user *usermem;
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size_t size = 128 - KASAN_GRANULE_SIZE;
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int __maybe_unused unused;
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kmem = kmalloc(size, GFP_KERNEL);
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if (!kmem)
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return;
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usermem = (char __user *)vm_mmap(NULL, 0, PAGE_SIZE,
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PROT_READ | PROT_WRITE | PROT_EXEC,
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MAP_ANONYMOUS | MAP_PRIVATE, 0);
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if (IS_ERR(usermem)) {
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pr_err("Failed to allocate user memory\n");
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kfree(kmem);
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return;
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}
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OPTIMIZER_HIDE_VAR(size);
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pr_info("out-of-bounds in copy_from_user()\n");
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unused = copy_from_user(kmem, usermem, size + 1);
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pr_info("out-of-bounds in copy_to_user()\n");
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unused = copy_to_user(usermem, kmem, size + 1);
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pr_info("out-of-bounds in __copy_from_user()\n");
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unused = __copy_from_user(kmem, usermem, size + 1);
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pr_info("out-of-bounds in __copy_to_user()\n");
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unused = __copy_to_user(usermem, kmem, size + 1);
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pr_info("out-of-bounds in __copy_from_user_inatomic()\n");
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unused = __copy_from_user_inatomic(kmem, usermem, size + 1);
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pr_info("out-of-bounds in __copy_to_user_inatomic()\n");
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unused = __copy_to_user_inatomic(usermem, kmem, size + 1);
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pr_info("out-of-bounds in strncpy_from_user()\n");
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unused = strncpy_from_user(kmem, usermem, size + 1);
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vm_munmap((unsigned long)usermem, PAGE_SIZE);
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kfree(kmem);
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}
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static struct kasan_rcu_info {
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int i;
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struct rcu_head rcu;
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} *global_rcu_ptr;
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static noinline void __init kasan_rcu_reclaim(struct rcu_head *rp)
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{
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struct kasan_rcu_info *fp = container_of(rp,
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struct kasan_rcu_info, rcu);
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kfree(fp);
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((volatile struct kasan_rcu_info *)fp)->i;
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}
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static noinline void __init kasan_rcu_uaf(void)
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{
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struct kasan_rcu_info *ptr;
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pr_info("use-after-free in kasan_rcu_reclaim\n");
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ptr = kmalloc(sizeof(struct kasan_rcu_info), GFP_KERNEL);
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if (!ptr) {
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pr_err("Allocation failed\n");
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return;
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}
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global_rcu_ptr = rcu_dereference_protected(ptr, NULL);
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call_rcu(&global_rcu_ptr->rcu, kasan_rcu_reclaim);
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}
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static noinline void __init kasan_workqueue_work(struct work_struct *work)
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{
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kfree(work);
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}
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static noinline void __init kasan_workqueue_uaf(void)
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{
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struct workqueue_struct *workqueue;
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struct work_struct *work;
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workqueue = create_workqueue("kasan_wq_test");
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if (!workqueue) {
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pr_err("Allocation failed\n");
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return;
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}
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work = kmalloc(sizeof(struct work_struct), GFP_KERNEL);
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if (!work) {
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pr_err("Allocation failed\n");
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return;
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}
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INIT_WORK(work, kasan_workqueue_work);
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queue_work(workqueue, work);
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destroy_workqueue(workqueue);
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pr_info("use-after-free on workqueue\n");
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((volatile struct work_struct *)work)->data;
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}
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static int __init test_kasan_module_init(void)
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{
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/*
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* Temporarily enable multi-shot mode. Otherwise, KASAN would only
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* report the first detected bug and panic the kernel if panic_on_warn
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* is enabled.
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*/
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bool multishot = kasan_save_enable_multi_shot();
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copy_user_test();
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kasan_rcu_uaf();
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kasan_workqueue_uaf();
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kasan_restore_multi_shot(multishot);
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return -EAGAIN;
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}
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module_init(test_kasan_module_init);
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MODULE_LICENSE("GPL");
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