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),
339 * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
340 * For larger allocations larger redzones are used.
342 static size_t optimal_redzone(size_t object_size)
345 object_size <= 64 - 16 ? 16 :
346 object_size <= 128 - 32 ? 32 :
347 object_size <= 512 - 64 ? 64 :
348 object_size <= 4096 - 128 ? 128 :
349 object_size <= (1 << 14) - 256 ? 256 :
350 object_size <= (1 << 15) - 512 ? 512 :
351 object_size <= (1 << 16) - 1024 ? 1024 : 2048;
355 void kasan_cache_create(struct kmem_cache *cache, size_t *size,
356 unsigned long *flags)
359 /* Make sure the adjusted size is still less than
360 * KMALLOC_MAX_CACHE_SIZE.
361 * TODO: this check is only useful for SLAB, but not SLUB. We'll need
362 * to skip it for SLUB when it starts using kasan_cache_create().
364 if (*size > KMALLOC_MAX_CACHE_SIZE -
365 sizeof(struct kasan_alloc_meta) -
366 sizeof(struct kasan_free_meta))
368 *flags |= SLAB_KASAN;
369 /* Add alloc meta. */
370 cache->kasan_info.alloc_meta_offset = *size;
371 *size += sizeof(struct kasan_alloc_meta);
374 if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor ||
375 cache->object_size < sizeof(struct kasan_free_meta)) {
376 cache->kasan_info.free_meta_offset = *size;
377 *size += sizeof(struct kasan_free_meta);
379 redzone_adjust = optimal_redzone(cache->object_size) -
380 (*size - cache->object_size);
381 if (redzone_adjust > 0)
382 *size += redzone_adjust;
383 *size = min(KMALLOC_MAX_CACHE_SIZE,
386 optimal_redzone(cache->object_size)));
390 void kasan_poison_slab(struct page *page)
392 kasan_poison_shadow(page_address(page),
393 PAGE_SIZE << compound_order(page),
394 KASAN_KMALLOC_REDZONE);
397 void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
399 kasan_unpoison_shadow(object, cache->object_size);
402 void kasan_poison_object_data(struct kmem_cache *cache, void *object)
404 kasan_poison_shadow(object,
405 round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
406 KASAN_KMALLOC_REDZONE);
408 if (cache->flags & SLAB_KASAN) {
409 struct kasan_alloc_meta *alloc_info =
410 get_alloc_info(cache, object);
411 alloc_info->state = KASAN_STATE_INIT;
416 static inline void set_track(struct kasan_track *track)
418 track->cpu = raw_smp_processor_id();
419 track->pid = current->pid;
420 track->when = jiffies;
424 struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
427 return (void *)object + cache->kasan_info.alloc_meta_offset;
430 struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
433 return (void *)object + cache->kasan_info.free_meta_offset;
437 void kasan_slab_alloc(struct kmem_cache *cache, void *object)
439 kasan_kmalloc(cache, object, cache->object_size);
442 void kasan_slab_free(struct kmem_cache *cache, void *object)
444 unsigned long size = cache->object_size;
445 unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
447 /* RCU slabs could be legally used after free within the RCU period */
448 if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
452 if (cache->flags & SLAB_KASAN) {
453 struct kasan_free_meta *free_info =
454 get_free_info(cache, object);
455 struct kasan_alloc_meta *alloc_info =
456 get_alloc_info(cache, object);
457 alloc_info->state = KASAN_STATE_FREE;
458 set_track(&free_info->track);
462 kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
465 void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size)
467 unsigned long redzone_start;
468 unsigned long redzone_end;
470 if (unlikely(object == NULL))
473 redzone_start = round_up((unsigned long)(object + size),
474 KASAN_SHADOW_SCALE_SIZE);
475 redzone_end = round_up((unsigned long)object + cache->object_size,
476 KASAN_SHADOW_SCALE_SIZE);
478 kasan_unpoison_shadow(object, size);
479 kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
480 KASAN_KMALLOC_REDZONE);
482 if (cache->flags & SLAB_KASAN) {
483 struct kasan_alloc_meta *alloc_info =
484 get_alloc_info(cache, object);
486 alloc_info->state = KASAN_STATE_ALLOC;
487 alloc_info->alloc_size = size;
488 set_track(&alloc_info->track);
492 EXPORT_SYMBOL(kasan_kmalloc);
494 void kasan_kmalloc_large(const void *ptr, size_t size)
497 unsigned long redzone_start;
498 unsigned long redzone_end;
500 if (unlikely(ptr == NULL))
503 page = virt_to_page(ptr);
504 redzone_start = round_up((unsigned long)(ptr + size),
505 KASAN_SHADOW_SCALE_SIZE);
506 redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
508 kasan_unpoison_shadow(ptr, size);
509 kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
513 void kasan_krealloc(const void *object, size_t size)
517 if (unlikely(object == ZERO_SIZE_PTR))
520 page = virt_to_head_page(object);
522 if (unlikely(!PageSlab(page)))
523 kasan_kmalloc_large(object, size);
525 kasan_kmalloc(page->slab_cache, object, size);
528 void kasan_kfree(void *ptr)
532 page = virt_to_head_page(ptr);
534 if (unlikely(!PageSlab(page)))
535 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
538 kasan_slab_free(page->slab_cache, ptr);
541 void kasan_kfree_large(const void *ptr)
543 struct page *page = virt_to_page(ptr);
545 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
549 int kasan_module_alloc(void *addr, size_t size)
553 unsigned long shadow_start;
555 shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
556 shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
559 if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
562 ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
563 shadow_start + shadow_size,
564 GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
565 PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
566 __builtin_return_address(0));
569 find_vm_area(addr)->flags |= VM_KASAN;
570 kmemleak_ignore(ret);
577 void kasan_free_shadow(const struct vm_struct *vm)
579 if (vm->flags & VM_KASAN)
580 vfree(kasan_mem_to_shadow(vm->addr));
583 static void register_global(struct kasan_global *global)
585 size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
587 kasan_unpoison_shadow(global->beg, global->size);
589 kasan_poison_shadow(global->beg + aligned_size,
590 global->size_with_redzone - aligned_size,
591 KASAN_GLOBAL_REDZONE);
594 void __asan_register_globals(struct kasan_global *globals, size_t size)
598 for (i = 0; i < size; i++)
599 register_global(&globals[i]);
601 EXPORT_SYMBOL(__asan_register_globals);
603 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
606 EXPORT_SYMBOL(__asan_unregister_globals);
608 #define DEFINE_ASAN_LOAD_STORE(size) \
609 void __asan_load##size(unsigned long addr) \
611 check_memory_region(addr, size, false); \
613 EXPORT_SYMBOL(__asan_load##size); \
614 __alias(__asan_load##size) \
615 void __asan_load##size##_noabort(unsigned long); \
616 EXPORT_SYMBOL(__asan_load##size##_noabort); \
617 void __asan_store##size(unsigned long addr) \
619 check_memory_region(addr, size, true); \
621 EXPORT_SYMBOL(__asan_store##size); \
622 __alias(__asan_store##size) \
623 void __asan_store##size##_noabort(unsigned long); \
624 EXPORT_SYMBOL(__asan_store##size##_noabort)
626 DEFINE_ASAN_LOAD_STORE(1);
627 DEFINE_ASAN_LOAD_STORE(2);
628 DEFINE_ASAN_LOAD_STORE(4);
629 DEFINE_ASAN_LOAD_STORE(8);
630 DEFINE_ASAN_LOAD_STORE(16);
632 void __asan_loadN(unsigned long addr, size_t size)
634 check_memory_region(addr, size, false);
636 EXPORT_SYMBOL(__asan_loadN);
638 __alias(__asan_loadN)
639 void __asan_loadN_noabort(unsigned long, size_t);
640 EXPORT_SYMBOL(__asan_loadN_noabort);
642 void __asan_storeN(unsigned long addr, size_t size)
644 check_memory_region(addr, size, true);
646 EXPORT_SYMBOL(__asan_storeN);
648 __alias(__asan_storeN)
649 void __asan_storeN_noabort(unsigned long, size_t);
650 EXPORT_SYMBOL(__asan_storeN_noabort);
652 /* to shut up compiler complaints */
653 void __asan_handle_no_return(void) {}
654 EXPORT_SYMBOL(__asan_handle_no_return);
656 #ifdef CONFIG_MEMORY_HOTPLUG
657 static int kasan_mem_notifier(struct notifier_block *nb,
658 unsigned long action, void *data)
660 return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
663 static int __init kasan_memhotplug_init(void)
665 pr_err("WARNING: KASAN doesn't support memory hot-add\n");
666 pr_err("Memory hot-add will be disabled\n");
668 hotplug_memory_notifier(kasan_mem_notifier, 0);
673 module_init(kasan_memhotplug_init);