2 * This file contains shadow memory manipulation code.
4 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
5 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 * Some code borrowed from https://github.com/xairy/kasan-prototype by
8 * Andrey Konovalov <adech.fo@gmail.com>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17 #define DISABLE_BRANCH_PROFILING
19 #include <linux/export.h>
20 #include <linux/init.h>
21 #include <linux/kernel.h>
22 #include <linux/kmemleak.h>
23 #include <linux/linkage.h>
24 #include <linux/memblock.h>
25 #include <linux/memory.h>
27 #include <linux/module.h>
28 #include <linux/printk.h>
29 #include <linux/sched.h>
30 #include <linux/slab.h>
31 #include <linux/stacktrace.h>
32 #include <linux/string.h>
33 #include <linux/types.h>
34 #include <linux/vmalloc.h>
35 #include <linux/kasan.h>
41 * Poisons the shadow memory for 'size' bytes starting from 'addr'.
42 * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
44 static void kasan_poison_shadow(const void *address, size_t size, u8 value)
46 void *shadow_start, *shadow_end;
48 shadow_start = kasan_mem_to_shadow(address);
49 shadow_end = kasan_mem_to_shadow(address + size);
51 memset(shadow_start, value, shadow_end - shadow_start);
54 void kasan_unpoison_shadow(const void *address, size_t size)
56 kasan_poison_shadow(address, size, 0);
58 if (size & KASAN_SHADOW_MASK) {
59 u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
60 *shadow = size & KASAN_SHADOW_MASK;
64 static void __kasan_unpoison_stack(struct task_struct *task, void *sp)
66 void *base = task_stack_page(task);
67 size_t size = sp - base;
69 kasan_unpoison_shadow(base, size);
72 /* Unpoison the entire stack for a task. */
73 void kasan_unpoison_task_stack(struct task_struct *task)
75 __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE);
78 /* Unpoison the stack for the current task beyond a watermark sp value. */
79 asmlinkage void kasan_unpoison_remaining_stack(void *sp)
81 __kasan_unpoison_stack(current, sp);
85 * All functions below always inlined so compiler could
86 * perform better optimizations in each of __asan_loadX/__assn_storeX
87 * depending on memory access size X.
90 static __always_inline bool memory_is_poisoned_1(unsigned long addr)
92 s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
94 if (unlikely(shadow_value)) {
95 s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
96 return unlikely(last_accessible_byte >= shadow_value);
102 static __always_inline bool memory_is_poisoned_2(unsigned long addr)
104 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
106 if (unlikely(*shadow_addr)) {
107 if (memory_is_poisoned_1(addr + 1))
111 * If single shadow byte covers 2-byte access, we don't
112 * need to do anything more. Otherwise, test the first
115 if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
118 return unlikely(*(u8 *)shadow_addr);
124 static __always_inline bool memory_is_poisoned_4(unsigned long addr)
126 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
128 if (unlikely(*shadow_addr)) {
129 if (memory_is_poisoned_1(addr + 3))
133 * If single shadow byte covers 4-byte access, we don't
134 * need to do anything more. Otherwise, test the first
137 if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
140 return unlikely(*(u8 *)shadow_addr);
146 static __always_inline bool memory_is_poisoned_8(unsigned long addr)
148 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
150 if (unlikely(*shadow_addr)) {
151 if (memory_is_poisoned_1(addr + 7))
155 * If single shadow byte covers 8-byte access, we don't
156 * need to do anything more. Otherwise, test the first
159 if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
162 return unlikely(*(u8 *)shadow_addr);
168 static __always_inline bool memory_is_poisoned_16(unsigned long addr)
170 u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr);
172 if (unlikely(*shadow_addr)) {
173 u16 shadow_first_bytes = *(u16 *)shadow_addr;
175 if (unlikely(shadow_first_bytes))
179 * If two shadow bytes covers 16-byte access, we don't
180 * need to do anything more. Otherwise, test the last
183 if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
186 return memory_is_poisoned_1(addr + 15);
192 static __always_inline unsigned long bytes_is_zero(const u8 *start,
196 if (unlikely(*start))
197 return (unsigned long)start;
205 static __always_inline unsigned long memory_is_zero(const void *start,
210 unsigned int prefix = (unsigned long)start % 8;
212 if (end - start <= 16)
213 return bytes_is_zero(start, end - start);
217 ret = bytes_is_zero(start, prefix);
223 words = (end - start) / 8;
225 if (unlikely(*(u64 *)start))
226 return bytes_is_zero(start, 8);
231 return bytes_is_zero(start, (end - start) % 8);
234 static __always_inline bool memory_is_poisoned_n(unsigned long addr,
239 ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
240 kasan_mem_to_shadow((void *)addr + size - 1) + 1);
243 unsigned long last_byte = addr + size - 1;
244 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
246 if (unlikely(ret != (unsigned long)last_shadow ||
247 ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
253 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
255 if (__builtin_constant_p(size)) {
258 return memory_is_poisoned_1(addr);
260 return memory_is_poisoned_2(addr);
262 return memory_is_poisoned_4(addr);
264 return memory_is_poisoned_8(addr);
266 return memory_is_poisoned_16(addr);
272 return memory_is_poisoned_n(addr, size);
276 static __always_inline void check_memory_region(unsigned long addr,
277 size_t size, bool write)
279 if (unlikely(size == 0))
282 if (unlikely((void *)addr <
283 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
284 kasan_report(addr, size, write, _RET_IP_);
288 if (likely(!memory_is_poisoned(addr, size)))
291 kasan_report(addr, size, write, _RET_IP_);
294 void __asan_loadN(unsigned long addr, size_t size);
295 void __asan_storeN(unsigned long addr, size_t size);
298 void *memset(void *addr, int c, size_t len)
300 __asan_storeN((unsigned long)addr, len);
302 return __memset(addr, c, len);
306 void *memmove(void *dest, const void *src, size_t len)
308 __asan_loadN((unsigned long)src, len);
309 __asan_storeN((unsigned long)dest, len);
311 return __memmove(dest, src, len);
315 void *memcpy(void *dest, const void *src, size_t len)
317 __asan_loadN((unsigned long)src, len);
318 __asan_storeN((unsigned long)dest, len);
320 return __memcpy(dest, src, len);
323 void kasan_alloc_pages(struct page *page, unsigned int order)
325 if (likely(!PageHighMem(page)))
326 kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
329 void kasan_free_pages(struct page *page, unsigned int order)
331 if (likely(!PageHighMem(page)))
332 kasan_poison_shadow(page_address(page),
337 void kasan_poison_slab(struct page *page)
339 kasan_poison_shadow(page_address(page),
340 PAGE_SIZE << compound_order(page),
341 KASAN_KMALLOC_REDZONE);
344 void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
346 kasan_unpoison_shadow(object, cache->object_size);
349 void kasan_poison_object_data(struct kmem_cache *cache, void *object)
351 kasan_poison_shadow(object,
352 round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
353 KASAN_KMALLOC_REDZONE);
356 void kasan_slab_alloc(struct kmem_cache *cache, void *object)
358 kasan_kmalloc(cache, object, cache->object_size);
361 void kasan_slab_free(struct kmem_cache *cache, void *object)
363 unsigned long size = cache->object_size;
364 unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
366 /* RCU slabs could be legally used after free within the RCU period */
367 if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
370 kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
373 void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size)
375 unsigned long redzone_start;
376 unsigned long redzone_end;
378 if (unlikely(object == NULL))
381 redzone_start = round_up((unsigned long)(object + size),
382 KASAN_SHADOW_SCALE_SIZE);
383 redzone_end = round_up((unsigned long)object + cache->object_size,
384 KASAN_SHADOW_SCALE_SIZE);
386 kasan_unpoison_shadow(object, size);
387 kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
388 KASAN_KMALLOC_REDZONE);
390 EXPORT_SYMBOL(kasan_kmalloc);
392 void kasan_kmalloc_large(const void *ptr, size_t size)
395 unsigned long redzone_start;
396 unsigned long redzone_end;
398 if (unlikely(ptr == NULL))
401 page = virt_to_page(ptr);
402 redzone_start = round_up((unsigned long)(ptr + size),
403 KASAN_SHADOW_SCALE_SIZE);
404 redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
406 kasan_unpoison_shadow(ptr, size);
407 kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
411 void kasan_krealloc(const void *object, size_t size)
415 if (unlikely(object == ZERO_SIZE_PTR))
418 page = virt_to_head_page(object);
420 if (unlikely(!PageSlab(page)))
421 kasan_kmalloc_large(object, size);
423 kasan_kmalloc(page->slab_cache, object, size);
426 void kasan_kfree(void *ptr)
430 page = virt_to_head_page(ptr);
432 if (unlikely(!PageSlab(page)))
433 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
436 kasan_slab_free(page->slab_cache, ptr);
439 void kasan_kfree_large(const void *ptr)
441 struct page *page = virt_to_page(ptr);
443 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
447 int kasan_module_alloc(void *addr, size_t size)
451 unsigned long shadow_start;
453 shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
454 shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
457 if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
460 ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
461 shadow_start + shadow_size,
462 GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
463 PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
464 __builtin_return_address(0));
467 find_vm_area(addr)->flags |= VM_KASAN;
468 kmemleak_ignore(ret);
475 void kasan_free_shadow(const struct vm_struct *vm)
477 if (vm->flags & VM_KASAN)
478 vfree(kasan_mem_to_shadow(vm->addr));
481 static void register_global(struct kasan_global *global)
483 size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
485 kasan_unpoison_shadow(global->beg, global->size);
487 kasan_poison_shadow(global->beg + aligned_size,
488 global->size_with_redzone - aligned_size,
489 KASAN_GLOBAL_REDZONE);
492 void __asan_register_globals(struct kasan_global *globals, size_t size)
496 for (i = 0; i < size; i++)
497 register_global(&globals[i]);
499 EXPORT_SYMBOL(__asan_register_globals);
501 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
504 EXPORT_SYMBOL(__asan_unregister_globals);
506 #define DEFINE_ASAN_LOAD_STORE(size) \
507 void __asan_load##size(unsigned long addr) \
509 check_memory_region(addr, size, false); \
511 EXPORT_SYMBOL(__asan_load##size); \
512 __alias(__asan_load##size) \
513 void __asan_load##size##_noabort(unsigned long); \
514 EXPORT_SYMBOL(__asan_load##size##_noabort); \
515 void __asan_store##size(unsigned long addr) \
517 check_memory_region(addr, size, true); \
519 EXPORT_SYMBOL(__asan_store##size); \
520 __alias(__asan_store##size) \
521 void __asan_store##size##_noabort(unsigned long); \
522 EXPORT_SYMBOL(__asan_store##size##_noabort)
524 DEFINE_ASAN_LOAD_STORE(1);
525 DEFINE_ASAN_LOAD_STORE(2);
526 DEFINE_ASAN_LOAD_STORE(4);
527 DEFINE_ASAN_LOAD_STORE(8);
528 DEFINE_ASAN_LOAD_STORE(16);
530 void __asan_loadN(unsigned long addr, size_t size)
532 check_memory_region(addr, size, false);
534 EXPORT_SYMBOL(__asan_loadN);
536 __alias(__asan_loadN)
537 void __asan_loadN_noabort(unsigned long, size_t);
538 EXPORT_SYMBOL(__asan_loadN_noabort);
540 void __asan_storeN(unsigned long addr, size_t size)
542 check_memory_region(addr, size, true);
544 EXPORT_SYMBOL(__asan_storeN);
546 __alias(__asan_storeN)
547 void __asan_storeN_noabort(unsigned long, size_t);
548 EXPORT_SYMBOL(__asan_storeN_noabort);
550 /* to shut up compiler complaints */
551 void __asan_handle_no_return(void) {}
552 EXPORT_SYMBOL(__asan_handle_no_return);
554 #ifdef CONFIG_MEMORY_HOTPLUG
555 static int kasan_mem_notifier(struct notifier_block *nb,
556 unsigned long action, void *data)
558 return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
561 static int __init kasan_memhotplug_init(void)
563 pr_err("WARNING: KASAN doesn't support memory hot-add\n");
564 pr_err("Memory hot-add will be disabled\n");
566 hotplug_memory_notifier(kasan_mem_notifier, 0);
571 module_init(kasan_memhotplug_init);