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1/*
2 * This file contains shadow memory manipulation code.
3 *
4 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
5 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
6 *
7 * Some code borrowed from https://github.com/xairy/kasan-prototype by
8 * Andrey Konovalov <adech.fo@gmail.com>
9 *
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.
13 *
14 */
15
16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17#define DISABLE_BRANCH_PROFILING
18
19#include <linux/export.h>
20#include <linux/interrupt.h>
21#include <linux/init.h>
22#include <linux/kasan.h>
23#include <linux/kernel.h>
24#include <linux/kmemleak.h>
25#include <linux/linkage.h>
26#include <linux/memblock.h>
27#include <linux/memory.h>
28#include <linux/mm.h>
29#include <linux/module.h>
30#include <linux/printk.h>
31#include <linux/sched.h>
32#include <linux/slab.h>
33#include <linux/stacktrace.h>
34#include <linux/string.h>
35#include <linux/types.h>
36#include <linux/vmalloc.h>
37
38#include "kasan.h"
39#include "../slab.h"
40
41/*
42 * Poisons the shadow memory for 'size' bytes starting from 'addr'.
43 * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
44 */
45static void kasan_poison_shadow(const void *address, size_t size, u8 value)
46{
47 void *shadow_start, *shadow_end;
48
49 shadow_start = kasan_mem_to_shadow(address);
50 shadow_end = kasan_mem_to_shadow(address + size);
51
52 memset(shadow_start, value, shadow_end - shadow_start);
53}
54
55void kasan_unpoison_shadow(const void *address, size_t size)
56{
57 kasan_poison_shadow(address, size, 0);
58
59 if (size & KASAN_SHADOW_MASK) {
60 u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
61 *shadow = size & KASAN_SHADOW_MASK;
62 }
63}
64
65static void __kasan_unpoison_stack(struct task_struct *task, void *sp)
66{
67 void *base = task_stack_page(task);
68 size_t size = sp - base;
69
70 kasan_unpoison_shadow(base, size);
71}
72
73/* Unpoison the entire stack for a task. */
74void kasan_unpoison_task_stack(struct task_struct *task)
75{
76 __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE);
77}
78
79/* Unpoison the stack for the current task beyond a watermark sp value. */
80asmlinkage void kasan_unpoison_remaining_stack(void *sp)
81{
82 __kasan_unpoison_stack(current, sp);
83}
84
85/*
86 * All functions below always inlined so compiler could
87 * perform better optimizations in each of __asan_loadX/__assn_storeX
88 * depending on memory access size X.
89 */
90
91static __always_inline bool memory_is_poisoned_1(unsigned long addr)
92{
93 s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
94
95 if (unlikely(shadow_value)) {
96 s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
97 return unlikely(last_accessible_byte >= shadow_value);
98 }
99
100 return false;
101}
102
103static __always_inline bool memory_is_poisoned_2(unsigned long addr)
104{
105 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
106
107 if (unlikely(*shadow_addr)) {
108 if (memory_is_poisoned_1(addr + 1))
109 return true;
110
111 /*
112 * If single shadow byte covers 2-byte access, we don't
113 * need to do anything more. Otherwise, test the first
114 * shadow byte.
115 */
116 if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
117 return false;
118
119 return unlikely(*(u8 *)shadow_addr);
120 }
121
122 return false;
123}
124
125static __always_inline bool memory_is_poisoned_4(unsigned long addr)
126{
127 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
128
129 if (unlikely(*shadow_addr)) {
130 if (memory_is_poisoned_1(addr + 3))
131 return true;
132
133 /*
134 * If single shadow byte covers 4-byte access, we don't
135 * need to do anything more. Otherwise, test the first
136 * shadow byte.
137 */
138 if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
139 return false;
140
141 return unlikely(*(u8 *)shadow_addr);
142 }
143
144 return false;
145}
146
147static __always_inline bool memory_is_poisoned_8(unsigned long addr)
148{
149 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
150
151 if (unlikely(*shadow_addr)) {
152 if (memory_is_poisoned_1(addr + 7))
153 return true;
154
155 /*
156 * If single shadow byte covers 8-byte access, we don't
157 * need to do anything more. Otherwise, test the first
158 * shadow byte.
159 */
160 if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
161 return false;
162
163 return unlikely(*(u8 *)shadow_addr);
164 }
165
166 return false;
167}
168
169static __always_inline bool memory_is_poisoned_16(unsigned long addr)
170{
171 u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr);
172
173 if (unlikely(*shadow_addr)) {
174 u16 shadow_first_bytes = *(u16 *)shadow_addr;
175
176 if (unlikely(shadow_first_bytes))
177 return true;
178
179 /*
180 * If two shadow bytes covers 16-byte access, we don't
181 * need to do anything more. Otherwise, test the last
182 * shadow byte.
183 */
184 if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
185 return false;
186
187 return memory_is_poisoned_1(addr + 15);
188 }
189
190 return false;
191}
192
193static __always_inline unsigned long bytes_is_zero(const u8 *start,
194 size_t size)
195{
196 while (size) {
197 if (unlikely(*start))
198 return (unsigned long)start;
199 start++;
200 size--;
201 }
202
203 return 0;
204}
205
206static __always_inline unsigned long memory_is_zero(const void *start,
207 const void *end)
208{
209 unsigned int words;
210 unsigned long ret;
211 unsigned int prefix = (unsigned long)start % 8;
212
213 if (end - start <= 16)
214 return bytes_is_zero(start, end - start);
215
216 if (prefix) {
217 prefix = 8 - prefix;
218 ret = bytes_is_zero(start, prefix);
219 if (unlikely(ret))
220 return ret;
221 start += prefix;
222 }
223
224 words = (end - start) / 8;
225 while (words) {
226 if (unlikely(*(u64 *)start))
227 return bytes_is_zero(start, 8);
228 start += 8;
229 words--;
230 }
231
232 return bytes_is_zero(start, (end - start) % 8);
233}
234
235static __always_inline bool memory_is_poisoned_n(unsigned long addr,
236 size_t size)
237{
238 unsigned long ret;
239
240 ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
241 kasan_mem_to_shadow((void *)addr + size - 1) + 1);
242
243 if (unlikely(ret)) {
244 unsigned long last_byte = addr + size - 1;
245 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
246
247 if (unlikely(ret != (unsigned long)last_shadow ||
248 ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
249 return true;
250 }
251 return false;
252}
253
254static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
255{
256 if (__builtin_constant_p(size)) {
257 switch (size) {
258 case 1:
259 return memory_is_poisoned_1(addr);
260 case 2:
261 return memory_is_poisoned_2(addr);
262 case 4:
263 return memory_is_poisoned_4(addr);
264 case 8:
265 return memory_is_poisoned_8(addr);
266 case 16:
267 return memory_is_poisoned_16(addr);
268 default:
269 BUILD_BUG();
270 }
271 }
272
273 return memory_is_poisoned_n(addr, size);
274}
275
276
277static __always_inline void check_memory_region(unsigned long addr,
278 size_t size, bool write)
279{
280 if (unlikely(size == 0))
281 return;
282
283 if (unlikely((void *)addr <
284 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
285 kasan_report(addr, size, write, _RET_IP_);
286 return;
287 }
288
289 if (likely(!memory_is_poisoned(addr, size)))
290 return;
291
292 kasan_report(addr, size, write, _RET_IP_);
293}
294
295void __asan_loadN(unsigned long addr, size_t size);
296void __asan_storeN(unsigned long addr, size_t size);
297
298#undef memset
299void *memset(void *addr, int c, size_t len)
300{
301 __asan_storeN((unsigned long)addr, len);
302
303 return __memset(addr, c, len);
304}
305
306#undef memmove
307void *memmove(void *dest, const void *src, size_t len)
308{
309 __asan_loadN((unsigned long)src, len);
310 __asan_storeN((unsigned long)dest, len);
311
312 return __memmove(dest, src, len);
313}
314
315#undef memcpy
316void *memcpy(void *dest, const void *src, size_t len)
317{
318 __asan_loadN((unsigned long)src, len);
319 __asan_storeN((unsigned long)dest, len);
320
321 return __memcpy(dest, src, len);
322}
323
324void kasan_alloc_pages(struct page *page, unsigned int order)
325{
326 if (likely(!PageHighMem(page)))
327 kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
328}
329
330void kasan_free_pages(struct page *page, unsigned int order)
331{
332 if (likely(!PageHighMem(page)))
333 kasan_poison_shadow(page_address(page),
334 PAGE_SIZE << order,
335 KASAN_FREE_PAGE);
336}
337
338#ifdef CONFIG_SLAB
339/*
340 * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
341 * For larger allocations larger redzones are used.
342 */
343static size_t optimal_redzone(size_t object_size)
344{
345 int rz =
346 object_size <= 64 - 16 ? 16 :
347 object_size <= 128 - 32 ? 32 :
348 object_size <= 512 - 64 ? 64 :
349 object_size <= 4096 - 128 ? 128 :
350 object_size <= (1 << 14) - 256 ? 256 :
351 object_size <= (1 << 15) - 512 ? 512 :
352 object_size <= (1 << 16) - 1024 ? 1024 : 2048;
353 return rz;
354}
355
356void kasan_cache_create(struct kmem_cache *cache, size_t *size,
357 unsigned long *flags)
358{
359 int redzone_adjust;
360 /* Make sure the adjusted size is still less than
361 * KMALLOC_MAX_CACHE_SIZE.
362 * TODO: this check is only useful for SLAB, but not SLUB. We'll need
363 * to skip it for SLUB when it starts using kasan_cache_create().
364 */
365 if (*size > KMALLOC_MAX_CACHE_SIZE -
366 sizeof(struct kasan_alloc_meta) -
367 sizeof(struct kasan_free_meta))
368 return;
369 *flags |= SLAB_KASAN;
370 /* Add alloc meta. */
371 cache->kasan_info.alloc_meta_offset = *size;
372 *size += sizeof(struct kasan_alloc_meta);
373
374 /* Add free meta. */
375 if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor ||
376 cache->object_size < sizeof(struct kasan_free_meta)) {
377 cache->kasan_info.free_meta_offset = *size;
378 *size += sizeof(struct kasan_free_meta);
379 }
380 redzone_adjust = optimal_redzone(cache->object_size) -
381 (*size - cache->object_size);
382 if (redzone_adjust > 0)
383 *size += redzone_adjust;
384 *size = min(KMALLOC_MAX_CACHE_SIZE,
385 max(*size,
386 cache->object_size +
387 optimal_redzone(cache->object_size)));
388}
389#endif
390
391void kasan_poison_slab(struct page *page)
392{
393 kasan_poison_shadow(page_address(page),
394 PAGE_SIZE << compound_order(page),
395 KASAN_KMALLOC_REDZONE);
396}
397
398void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
399{
400 kasan_unpoison_shadow(object, cache->object_size);
401}
402
403void kasan_poison_object_data(struct kmem_cache *cache, void *object)
404{
405 kasan_poison_shadow(object,
406 round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
407 KASAN_KMALLOC_REDZONE);
408#ifdef CONFIG_SLAB
409 if (cache->flags & SLAB_KASAN) {
410 struct kasan_alloc_meta *alloc_info =
411 get_alloc_info(cache, object);
412 alloc_info->state = KASAN_STATE_INIT;
413 }
414#endif
415}
416
417#ifdef CONFIG_SLAB
418static inline int in_irqentry_text(unsigned long ptr)
419{
420 return (ptr >= (unsigned long)&__irqentry_text_start &&
421 ptr < (unsigned long)&__irqentry_text_end) ||
422 (ptr >= (unsigned long)&__softirqentry_text_start &&
423 ptr < (unsigned long)&__softirqentry_text_end);
424}
425
426static inline void filter_irq_stacks(struct stack_trace *trace)
427{
428 int i;
429
430 if (!trace->nr_entries)
431 return;
432 for (i = 0; i < trace->nr_entries; i++)
433 if (in_irqentry_text(trace->entries[i])) {
434 /* Include the irqentry function into the stack. */
435 trace->nr_entries = i + 1;
436 break;
437 }
438}
439
440static inline depot_stack_handle_t save_stack(gfp_t flags)
441{
442 unsigned long entries[KASAN_STACK_DEPTH];
443 struct stack_trace trace = {
444 .nr_entries = 0,
445 .entries = entries,
446 .max_entries = KASAN_STACK_DEPTH,
447 .skip = 0
448 };
449
450 save_stack_trace(&trace);
451 filter_irq_stacks(&trace);
452 if (trace.nr_entries != 0 &&
453 trace.entries[trace.nr_entries-1] == ULONG_MAX)
454 trace.nr_entries--;
455
456 return depot_save_stack(&trace, flags);
457}
458
459static inline void set_track(struct kasan_track *track, gfp_t flags)
460{
461 track->pid = current->pid;
462 track->stack = save_stack(flags);
463}
464
465struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
466 const void *object)
467{
468 BUILD_BUG_ON(sizeof(struct kasan_alloc_meta) > 32);
469 return (void *)object + cache->kasan_info.alloc_meta_offset;
470}
471
472struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
473 const void *object)
474{
475 BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
476 return (void *)object + cache->kasan_info.free_meta_offset;
477}
478#endif
479
480void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
481{
482 kasan_kmalloc(cache, object, cache->object_size, flags);
483}
484
485void kasan_slab_free(struct kmem_cache *cache, void *object)
486{
487 unsigned long size = cache->object_size;
488 unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
489
490 /* RCU slabs could be legally used after free within the RCU period */
491 if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
492 return;
493
494#ifdef CONFIG_SLAB
495 if (cache->flags & SLAB_KASAN) {
496 struct kasan_free_meta *free_info =
497 get_free_info(cache, object);
498 struct kasan_alloc_meta *alloc_info =
499 get_alloc_info(cache, object);
500 alloc_info->state = KASAN_STATE_FREE;
501 set_track(&free_info->track, GFP_NOWAIT);
502 }
503#endif
504
505 kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
506}
507
508void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
509 gfp_t flags)
510{
511 unsigned long redzone_start;
512 unsigned long redzone_end;
513
514 if (unlikely(object == NULL))
515 return;
516
517 redzone_start = round_up((unsigned long)(object + size),
518 KASAN_SHADOW_SCALE_SIZE);
519 redzone_end = round_up((unsigned long)object + cache->object_size,
520 KASAN_SHADOW_SCALE_SIZE);
521
522 kasan_unpoison_shadow(object, size);
523 kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
524 KASAN_KMALLOC_REDZONE);
525#ifdef CONFIG_SLAB
526 if (cache->flags & SLAB_KASAN) {
527 struct kasan_alloc_meta *alloc_info =
528 get_alloc_info(cache, object);
529
530 alloc_info->state = KASAN_STATE_ALLOC;
531 alloc_info->alloc_size = size;
532 set_track(&alloc_info->track, flags);
533 }
534#endif
535}
536EXPORT_SYMBOL(kasan_kmalloc);
537
538void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
539{
540 struct page *page;
541 unsigned long redzone_start;
542 unsigned long redzone_end;
543
544 if (unlikely(ptr == NULL))
545 return;
546
547 page = virt_to_page(ptr);
548 redzone_start = round_up((unsigned long)(ptr + size),
549 KASAN_SHADOW_SCALE_SIZE);
550 redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
551
552 kasan_unpoison_shadow(ptr, size);
553 kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
554 KASAN_PAGE_REDZONE);
555}
556
557void kasan_krealloc(const void *object, size_t size, gfp_t flags)
558{
559 struct page *page;
560
561 if (unlikely(object == ZERO_SIZE_PTR))
562 return;
563
564 page = virt_to_head_page(object);
565
566 if (unlikely(!PageSlab(page)))
567 kasan_kmalloc_large(object, size, flags);
568 else
569 kasan_kmalloc(page->slab_cache, object, size, flags);
570}
571
572void kasan_kfree(void *ptr)
573{
574 struct page *page;
575
576 page = virt_to_head_page(ptr);
577
578 if (unlikely(!PageSlab(page)))
579 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
580 KASAN_FREE_PAGE);
581 else
582 kasan_slab_free(page->slab_cache, ptr);
583}
584
585void kasan_kfree_large(const void *ptr)
586{
587 struct page *page = virt_to_page(ptr);
588
589 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
590 KASAN_FREE_PAGE);
591}
592
593int kasan_module_alloc(void *addr, size_t size)
594{
595 void *ret;
596 size_t shadow_size;
597 unsigned long shadow_start;
598
599 shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
600 shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
601 PAGE_SIZE);
602
603 if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
604 return -EINVAL;
605
606 ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
607 shadow_start + shadow_size,
608 GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
609 PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
610 __builtin_return_address(0));
611
612 if (ret) {
613 find_vm_area(addr)->flags |= VM_KASAN;
614 kmemleak_ignore(ret);
615 return 0;
616 }
617
618 return -ENOMEM;
619}
620
621void kasan_free_shadow(const struct vm_struct *vm)
622{
623 if (vm->flags & VM_KASAN)
624 vfree(kasan_mem_to_shadow(vm->addr));
625}
626
627static void register_global(struct kasan_global *global)
628{
629 size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
630
631 kasan_unpoison_shadow(global->beg, global->size);
632
633 kasan_poison_shadow(global->beg + aligned_size,
634 global->size_with_redzone - aligned_size,
635 KASAN_GLOBAL_REDZONE);
636}
637
638void __asan_register_globals(struct kasan_global *globals, size_t size)
639{
640 int i;
641
642 for (i = 0; i < size; i++)
643 register_global(&globals[i]);
644}
645EXPORT_SYMBOL(__asan_register_globals);
646
647void __asan_unregister_globals(struct kasan_global *globals, size_t size)
648{
649}
650EXPORT_SYMBOL(__asan_unregister_globals);
651
652#define DEFINE_ASAN_LOAD_STORE(size) \
653 void __asan_load##size(unsigned long addr) \
654 { \
655 check_memory_region(addr, size, false); \
656 } \
657 EXPORT_SYMBOL(__asan_load##size); \
658 __alias(__asan_load##size) \
659 void __asan_load##size##_noabort(unsigned long); \
660 EXPORT_SYMBOL(__asan_load##size##_noabort); \
661 void __asan_store##size(unsigned long addr) \
662 { \
663 check_memory_region(addr, size, true); \
664 } \
665 EXPORT_SYMBOL(__asan_store##size); \
666 __alias(__asan_store##size) \
667 void __asan_store##size##_noabort(unsigned long); \
668 EXPORT_SYMBOL(__asan_store##size##_noabort)
669
670DEFINE_ASAN_LOAD_STORE(1);
671DEFINE_ASAN_LOAD_STORE(2);
672DEFINE_ASAN_LOAD_STORE(4);
673DEFINE_ASAN_LOAD_STORE(8);
674DEFINE_ASAN_LOAD_STORE(16);
675
676void __asan_loadN(unsigned long addr, size_t size)
677{
678 check_memory_region(addr, size, false);
679}
680EXPORT_SYMBOL(__asan_loadN);
681
682__alias(__asan_loadN)
683void __asan_loadN_noabort(unsigned long, size_t);
684EXPORT_SYMBOL(__asan_loadN_noabort);
685
686void __asan_storeN(unsigned long addr, size_t size)
687{
688 check_memory_region(addr, size, true);
689}
690EXPORT_SYMBOL(__asan_storeN);
691
692__alias(__asan_storeN)
693void __asan_storeN_noabort(unsigned long, size_t);
694EXPORT_SYMBOL(__asan_storeN_noabort);
695
696/* to shut up compiler complaints */
697void __asan_handle_no_return(void) {}
698EXPORT_SYMBOL(__asan_handle_no_return);
699
700#ifdef CONFIG_MEMORY_HOTPLUG
701static int kasan_mem_notifier(struct notifier_block *nb,
702 unsigned long action, void *data)
703{
704 return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
705}
706
707static int __init kasan_memhotplug_init(void)
708{
709 pr_err("WARNING: KASAN doesn't support memory hot-add\n");
710 pr_err("Memory hot-add will be disabled\n");
711
712 hotplug_memory_notifier(kasan_mem_notifier, 0);
713
714 return 0;
715}
716
717module_init(kasan_memhotplug_init);
718#endif