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 of code borrowed from https://github.com/xairy/linux 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/memblock.h>
23 #include <linux/memory.h>
25 #include <linux/module.h>
26 #include <linux/printk.h>
27 #include <linux/sched.h>
28 #include <linux/slab.h>
29 #include <linux/stacktrace.h>
30 #include <linux/string.h>
31 #include <linux/types.h>
32 #include <linux/vmalloc.h>
33 #include <linux/kasan.h>
39 * Poisons the shadow memory for 'size' bytes starting from 'addr'.
40 * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
42 static void kasan_poison_shadow(const void *address, size_t size, u8 value)
44 void *shadow_start, *shadow_end;
46 shadow_start = kasan_mem_to_shadow(address);
47 shadow_end = kasan_mem_to_shadow(address + size);
49 memset(shadow_start, value, shadow_end - shadow_start);
52 void kasan_unpoison_shadow(const void *address, size_t size)
54 kasan_poison_shadow(address, size, 0);
56 if (size & KASAN_SHADOW_MASK) {
57 u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
58 *shadow = size & KASAN_SHADOW_MASK;
64 * All functions below always inlined so compiler could
65 * perform better optimizations in each of __asan_loadX/__assn_storeX
66 * depending on memory access size X.
69 static __always_inline bool memory_is_poisoned_1(unsigned long addr)
71 s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
73 if (unlikely(shadow_value)) {
74 s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
75 return unlikely(last_accessible_byte >= shadow_value);
81 static __always_inline bool memory_is_poisoned_2(unsigned long addr)
83 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
85 if (unlikely(*shadow_addr)) {
86 if (memory_is_poisoned_1(addr + 1))
89 if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
92 return unlikely(*(u8 *)shadow_addr);
98 static __always_inline bool memory_is_poisoned_4(unsigned long addr)
100 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
102 if (unlikely(*shadow_addr)) {
103 if (memory_is_poisoned_1(addr + 3))
106 if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
109 return unlikely(*(u8 *)shadow_addr);
115 static __always_inline bool memory_is_poisoned_8(unsigned long addr)
117 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
119 if (unlikely(*shadow_addr)) {
120 if (memory_is_poisoned_1(addr + 7))
123 if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7))
126 return unlikely(*(u8 *)shadow_addr);
132 static __always_inline bool memory_is_poisoned_16(unsigned long addr)
134 u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr);
136 if (unlikely(*shadow_addr)) {
137 u16 shadow_first_bytes = *(u16 *)shadow_addr;
139 if (unlikely(shadow_first_bytes))
142 if (likely(IS_ALIGNED(addr, 8)))
145 return memory_is_poisoned_1(addr + 15);
151 static __always_inline unsigned long bytes_is_zero(const u8 *start,
155 if (unlikely(*start))
156 return (unsigned long)start;
164 static __always_inline unsigned long memory_is_zero(const void *start,
169 unsigned int prefix = (unsigned long)start % 8;
171 if (end - start <= 16)
172 return bytes_is_zero(start, end - start);
176 ret = bytes_is_zero(start, prefix);
182 words = (end - start) / 8;
184 if (unlikely(*(u64 *)start))
185 return bytes_is_zero(start, 8);
190 return bytes_is_zero(start, (end - start) % 8);
193 static __always_inline bool memory_is_poisoned_n(unsigned long addr,
198 ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
199 kasan_mem_to_shadow((void *)addr + size - 1) + 1);
202 unsigned long last_byte = addr + size - 1;
203 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
205 if (unlikely(ret != (unsigned long)last_shadow ||
206 ((last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
212 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
214 if (__builtin_constant_p(size)) {
217 return memory_is_poisoned_1(addr);
219 return memory_is_poisoned_2(addr);
221 return memory_is_poisoned_4(addr);
223 return memory_is_poisoned_8(addr);
225 return memory_is_poisoned_16(addr);
231 return memory_is_poisoned_n(addr, size);
235 static __always_inline void check_memory_region(unsigned long addr,
236 size_t size, bool write)
238 if (unlikely(size == 0))
241 if (unlikely((void *)addr <
242 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
243 kasan_report(addr, size, write, _RET_IP_);
247 if (likely(!memory_is_poisoned(addr, size)))
250 kasan_report(addr, size, write, _RET_IP_);
253 void __asan_loadN(unsigned long addr, size_t size);
254 void __asan_storeN(unsigned long addr, size_t size);
257 void *memset(void *addr, int c, size_t len)
259 __asan_storeN((unsigned long)addr, len);
261 return __memset(addr, c, len);
265 void *memmove(void *dest, const void *src, size_t len)
267 __asan_loadN((unsigned long)src, len);
268 __asan_storeN((unsigned long)dest, len);
270 return __memmove(dest, src, len);
274 void *memcpy(void *dest, const void *src, size_t len)
276 __asan_loadN((unsigned long)src, len);
277 __asan_storeN((unsigned long)dest, len);
279 return __memcpy(dest, src, len);
282 void kasan_alloc_pages(struct page *page, unsigned int order)
284 if (likely(!PageHighMem(page)))
285 kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
288 void kasan_free_pages(struct page *page, unsigned int order)
290 if (likely(!PageHighMem(page)))
291 kasan_poison_shadow(page_address(page),
296 void kasan_poison_slab(struct page *page)
298 kasan_poison_shadow(page_address(page),
299 PAGE_SIZE << compound_order(page),
300 KASAN_KMALLOC_REDZONE);
303 void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
305 kasan_unpoison_shadow(object, cache->object_size);
308 void kasan_poison_object_data(struct kmem_cache *cache, void *object)
310 kasan_poison_shadow(object,
311 round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
312 KASAN_KMALLOC_REDZONE);
315 void kasan_slab_alloc(struct kmem_cache *cache, void *object)
317 kasan_kmalloc(cache, object, cache->object_size);
320 void kasan_slab_free(struct kmem_cache *cache, void *object)
322 unsigned long size = cache->object_size;
323 unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
325 /* RCU slabs could be legally used after free within the RCU period */
326 if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
329 kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
332 void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size)
334 unsigned long redzone_start;
335 unsigned long redzone_end;
337 if (unlikely(object == NULL))
340 redzone_start = round_up((unsigned long)(object + size),
341 KASAN_SHADOW_SCALE_SIZE);
342 redzone_end = round_up((unsigned long)object + cache->object_size,
343 KASAN_SHADOW_SCALE_SIZE);
345 kasan_unpoison_shadow(object, size);
346 kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
347 KASAN_KMALLOC_REDZONE);
349 EXPORT_SYMBOL(kasan_kmalloc);
351 void kasan_kmalloc_large(const void *ptr, size_t size)
354 unsigned long redzone_start;
355 unsigned long redzone_end;
357 if (unlikely(ptr == NULL))
360 page = virt_to_page(ptr);
361 redzone_start = round_up((unsigned long)(ptr + size),
362 KASAN_SHADOW_SCALE_SIZE);
363 redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
365 kasan_unpoison_shadow(ptr, size);
366 kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
370 void kasan_krealloc(const void *object, size_t size)
374 if (unlikely(object == ZERO_SIZE_PTR))
377 page = virt_to_head_page(object);
379 if (unlikely(!PageSlab(page)))
380 kasan_kmalloc_large(object, size);
382 kasan_kmalloc(page->slab_cache, object, size);
385 void kasan_kfree(void *ptr)
389 page = virt_to_head_page(ptr);
391 if (unlikely(!PageSlab(page)))
392 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
395 kasan_slab_free(page->slab_cache, ptr);
398 void kasan_kfree_large(const void *ptr)
400 struct page *page = virt_to_page(ptr);
402 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
406 int kasan_module_alloc(void *addr, size_t size)
410 unsigned long shadow_start;
412 shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
413 shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
416 if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
419 ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
420 shadow_start + shadow_size,
421 GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
422 PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
423 __builtin_return_address(0));
426 find_vm_area(addr)->flags |= VM_KASAN;
433 void kasan_free_shadow(const struct vm_struct *vm)
435 if (vm->flags & VM_KASAN)
436 vfree(kasan_mem_to_shadow(vm->addr));
439 static void register_global(struct kasan_global *global)
441 size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
443 kasan_unpoison_shadow(global->beg, global->size);
445 kasan_poison_shadow(global->beg + aligned_size,
446 global->size_with_redzone - aligned_size,
447 KASAN_GLOBAL_REDZONE);
450 void __asan_register_globals(struct kasan_global *globals, size_t size)
454 for (i = 0; i < size; i++)
455 register_global(&globals[i]);
457 EXPORT_SYMBOL(__asan_register_globals);
459 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
462 EXPORT_SYMBOL(__asan_unregister_globals);
464 #define DEFINE_ASAN_LOAD_STORE(size) \
465 void __asan_load##size(unsigned long addr) \
467 check_memory_region(addr, size, false); \
469 EXPORT_SYMBOL(__asan_load##size); \
470 __alias(__asan_load##size) \
471 void __asan_load##size##_noabort(unsigned long); \
472 EXPORT_SYMBOL(__asan_load##size##_noabort); \
473 void __asan_store##size(unsigned long addr) \
475 check_memory_region(addr, size, true); \
477 EXPORT_SYMBOL(__asan_store##size); \
478 __alias(__asan_store##size) \
479 void __asan_store##size##_noabort(unsigned long); \
480 EXPORT_SYMBOL(__asan_store##size##_noabort)
482 DEFINE_ASAN_LOAD_STORE(1);
483 DEFINE_ASAN_LOAD_STORE(2);
484 DEFINE_ASAN_LOAD_STORE(4);
485 DEFINE_ASAN_LOAD_STORE(8);
486 DEFINE_ASAN_LOAD_STORE(16);
488 void __asan_loadN(unsigned long addr, size_t size)
490 check_memory_region(addr, size, false);
492 EXPORT_SYMBOL(__asan_loadN);
494 __alias(__asan_loadN)
495 void __asan_loadN_noabort(unsigned long, size_t);
496 EXPORT_SYMBOL(__asan_loadN_noabort);
498 void __asan_storeN(unsigned long addr, size_t size)
500 check_memory_region(addr, size, true);
502 EXPORT_SYMBOL(__asan_storeN);
504 __alias(__asan_storeN)
505 void __asan_storeN_noabort(unsigned long, size_t);
506 EXPORT_SYMBOL(__asan_storeN_noabort);
508 /* to shut up compiler complaints */
509 void __asan_handle_no_return(void) {}
510 EXPORT_SYMBOL(__asan_handle_no_return);
512 #ifdef CONFIG_MEMORY_HOTPLUG
513 static int kasan_mem_notifier(struct notifier_block *nb,
514 unsigned long action, void *data)
516 return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
519 static int __init kasan_memhotplug_init(void)
521 pr_err("WARNING: KASan doesn't support memory hot-add\n");
522 pr_err("Memory hot-add will be disabled\n");
524 hotplug_memory_notifier(kasan_mem_notifier, 0);
529 module_init(kasan_memhotplug_init);