3fb497d4fbf82bbe83997b35c1b305ae38686330
[sfrench/cifs-2.6.git] / mm / kasan / kasan.c
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/sched/task_stack.h>
33 #include <linux/slab.h>
34 #include <linux/stacktrace.h>
35 #include <linux/string.h>
36 #include <linux/types.h>
37 #include <linux/vmalloc.h>
38 #include <linux/bug.h>
39
40 #include "kasan.h"
41 #include "../slab.h"
42
43 void kasan_enable_current(void)
44 {
45         current->kasan_depth++;
46 }
47
48 void kasan_disable_current(void)
49 {
50         current->kasan_depth--;
51 }
52
53 /*
54  * Poisons the shadow memory for 'size' bytes starting from 'addr'.
55  * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
56  */
57 static void kasan_poison_shadow(const void *address, size_t size, u8 value)
58 {
59         void *shadow_start, *shadow_end;
60
61         shadow_start = kasan_mem_to_shadow(address);
62         shadow_end = kasan_mem_to_shadow(address + size);
63
64         memset(shadow_start, value, shadow_end - shadow_start);
65 }
66
67 void kasan_unpoison_shadow(const void *address, size_t size)
68 {
69         kasan_poison_shadow(address, size, 0);
70
71         if (size & KASAN_SHADOW_MASK) {
72                 u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
73                 *shadow = size & KASAN_SHADOW_MASK;
74         }
75 }
76
77 static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
78 {
79         void *base = task_stack_page(task);
80         size_t size = sp - base;
81
82         kasan_unpoison_shadow(base, size);
83 }
84
85 /* Unpoison the entire stack for a task. */
86 void kasan_unpoison_task_stack(struct task_struct *task)
87 {
88         __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE);
89 }
90
91 /* Unpoison the stack for the current task beyond a watermark sp value. */
92 asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
93 {
94         /*
95          * Calculate the task stack base address.  Avoid using 'current'
96          * because this function is called by early resume code which hasn't
97          * yet set up the percpu register (%gs).
98          */
99         void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
100
101         kasan_unpoison_shadow(base, watermark - base);
102 }
103
104 /*
105  * Clear all poison for the region between the current SP and a provided
106  * watermark value, as is sometimes required prior to hand-crafted asm function
107  * returns in the middle of functions.
108  */
109 void kasan_unpoison_stack_above_sp_to(const void *watermark)
110 {
111         const void *sp = __builtin_frame_address(0);
112         size_t size = watermark - sp;
113
114         if (WARN_ON(sp > watermark))
115                 return;
116         kasan_unpoison_shadow(sp, size);
117 }
118
119 /*
120  * All functions below always inlined so compiler could
121  * perform better optimizations in each of __asan_loadX/__assn_storeX
122  * depending on memory access size X.
123  */
124
125 static __always_inline bool memory_is_poisoned_1(unsigned long addr)
126 {
127         s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
128
129         if (unlikely(shadow_value)) {
130                 s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
131                 return unlikely(last_accessible_byte >= shadow_value);
132         }
133
134         return false;
135 }
136
137 static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
138                                                 unsigned long size)
139 {
140         u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
141
142         /*
143          * Access crosses 8(shadow size)-byte boundary. Such access maps
144          * into 2 shadow bytes, so we need to check them both.
145          */
146         if (unlikely(((addr + size - 1) & KASAN_SHADOW_MASK) < size - 1))
147                 return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
148
149         return memory_is_poisoned_1(addr + size - 1);
150 }
151
152 static __always_inline bool memory_is_poisoned_16(unsigned long addr)
153 {
154         u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
155
156         /* Unaligned 16-bytes access maps into 3 shadow bytes. */
157         if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
158                 return *shadow_addr || memory_is_poisoned_1(addr + 15);
159
160         return *shadow_addr;
161 }
162
163 static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
164                                         size_t size)
165 {
166         while (size) {
167                 if (unlikely(*start))
168                         return (unsigned long)start;
169                 start++;
170                 size--;
171         }
172
173         return 0;
174 }
175
176 static __always_inline unsigned long memory_is_nonzero(const void *start,
177                                                 const void *end)
178 {
179         unsigned int words;
180         unsigned long ret;
181         unsigned int prefix = (unsigned long)start % 8;
182
183         if (end - start <= 16)
184                 return bytes_is_nonzero(start, end - start);
185
186         if (prefix) {
187                 prefix = 8 - prefix;
188                 ret = bytes_is_nonzero(start, prefix);
189                 if (unlikely(ret))
190                         return ret;
191                 start += prefix;
192         }
193
194         words = (end - start) / 8;
195         while (words) {
196                 if (unlikely(*(u64 *)start))
197                         return bytes_is_nonzero(start, 8);
198                 start += 8;
199                 words--;
200         }
201
202         return bytes_is_nonzero(start, (end - start) % 8);
203 }
204
205 static __always_inline bool memory_is_poisoned_n(unsigned long addr,
206                                                 size_t size)
207 {
208         unsigned long ret;
209
210         ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
211                         kasan_mem_to_shadow((void *)addr + size - 1) + 1);
212
213         if (unlikely(ret)) {
214                 unsigned long last_byte = addr + size - 1;
215                 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
216
217                 if (unlikely(ret != (unsigned long)last_shadow ||
218                         ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
219                         return true;
220         }
221         return false;
222 }
223
224 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
225 {
226         if (__builtin_constant_p(size)) {
227                 switch (size) {
228                 case 1:
229                         return memory_is_poisoned_1(addr);
230                 case 2:
231                 case 4:
232                 case 8:
233                         return memory_is_poisoned_2_4_8(addr, size);
234                 case 16:
235                         return memory_is_poisoned_16(addr);
236                 default:
237                         BUILD_BUG();
238                 }
239         }
240
241         return memory_is_poisoned_n(addr, size);
242 }
243
244 static __always_inline void check_memory_region_inline(unsigned long addr,
245                                                 size_t size, bool write,
246                                                 unsigned long ret_ip)
247 {
248         if (unlikely(size == 0))
249                 return;
250
251         if (unlikely((void *)addr <
252                 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
253                 kasan_report(addr, size, write, ret_ip);
254                 return;
255         }
256
257         if (likely(!memory_is_poisoned(addr, size)))
258                 return;
259
260         kasan_report(addr, size, write, ret_ip);
261 }
262
263 static void check_memory_region(unsigned long addr,
264                                 size_t size, bool write,
265                                 unsigned long ret_ip)
266 {
267         check_memory_region_inline(addr, size, write, ret_ip);
268 }
269
270 void kasan_check_read(const volatile void *p, unsigned int size)
271 {
272         check_memory_region((unsigned long)p, size, false, _RET_IP_);
273 }
274 EXPORT_SYMBOL(kasan_check_read);
275
276 void kasan_check_write(const volatile void *p, unsigned int size)
277 {
278         check_memory_region((unsigned long)p, size, true, _RET_IP_);
279 }
280 EXPORT_SYMBOL(kasan_check_write);
281
282 #undef memset
283 void *memset(void *addr, int c, size_t len)
284 {
285         check_memory_region((unsigned long)addr, len, true, _RET_IP_);
286
287         return __memset(addr, c, len);
288 }
289
290 #undef memmove
291 void *memmove(void *dest, const void *src, size_t len)
292 {
293         check_memory_region((unsigned long)src, len, false, _RET_IP_);
294         check_memory_region((unsigned long)dest, len, true, _RET_IP_);
295
296         return __memmove(dest, src, len);
297 }
298
299 #undef memcpy
300 void *memcpy(void *dest, const void *src, size_t len)
301 {
302         check_memory_region((unsigned long)src, len, false, _RET_IP_);
303         check_memory_region((unsigned long)dest, len, true, _RET_IP_);
304
305         return __memcpy(dest, src, len);
306 }
307
308 void kasan_alloc_pages(struct page *page, unsigned int order)
309 {
310         if (likely(!PageHighMem(page)))
311                 kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
312 }
313
314 void kasan_free_pages(struct page *page, unsigned int order)
315 {
316         if (likely(!PageHighMem(page)))
317                 kasan_poison_shadow(page_address(page),
318                                 PAGE_SIZE << order,
319                                 KASAN_FREE_PAGE);
320 }
321
322 /*
323  * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
324  * For larger allocations larger redzones are used.
325  */
326 static size_t optimal_redzone(size_t object_size)
327 {
328         int rz =
329                 object_size <= 64        - 16   ? 16 :
330                 object_size <= 128       - 32   ? 32 :
331                 object_size <= 512       - 64   ? 64 :
332                 object_size <= 4096      - 128  ? 128 :
333                 object_size <= (1 << 14) - 256  ? 256 :
334                 object_size <= (1 << 15) - 512  ? 512 :
335                 object_size <= (1 << 16) - 1024 ? 1024 : 2048;
336         return rz;
337 }
338
339 void kasan_cache_create(struct kmem_cache *cache, size_t *size,
340                         slab_flags_t *flags)
341 {
342         int redzone_adjust;
343         int orig_size = *size;
344
345         /* Add alloc meta. */
346         cache->kasan_info.alloc_meta_offset = *size;
347         *size += sizeof(struct kasan_alloc_meta);
348
349         /* Add free meta. */
350         if (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor ||
351             cache->object_size < sizeof(struct kasan_free_meta)) {
352                 cache->kasan_info.free_meta_offset = *size;
353                 *size += sizeof(struct kasan_free_meta);
354         }
355         redzone_adjust = optimal_redzone(cache->object_size) -
356                 (*size - cache->object_size);
357
358         if (redzone_adjust > 0)
359                 *size += redzone_adjust;
360
361         *size = min(KMALLOC_MAX_SIZE, max(*size, cache->object_size +
362                                         optimal_redzone(cache->object_size)));
363
364         /*
365          * If the metadata doesn't fit, don't enable KASAN at all.
366          */
367         if (*size <= cache->kasan_info.alloc_meta_offset ||
368                         *size <= cache->kasan_info.free_meta_offset) {
369                 cache->kasan_info.alloc_meta_offset = 0;
370                 cache->kasan_info.free_meta_offset = 0;
371                 *size = orig_size;
372                 return;
373         }
374
375         *flags |= SLAB_KASAN;
376 }
377
378 void kasan_cache_shrink(struct kmem_cache *cache)
379 {
380         quarantine_remove_cache(cache);
381 }
382
383 void kasan_cache_shutdown(struct kmem_cache *cache)
384 {
385         quarantine_remove_cache(cache);
386 }
387
388 size_t kasan_metadata_size(struct kmem_cache *cache)
389 {
390         return (cache->kasan_info.alloc_meta_offset ?
391                 sizeof(struct kasan_alloc_meta) : 0) +
392                 (cache->kasan_info.free_meta_offset ?
393                 sizeof(struct kasan_free_meta) : 0);
394 }
395
396 void kasan_poison_slab(struct page *page)
397 {
398         kasan_poison_shadow(page_address(page),
399                         PAGE_SIZE << compound_order(page),
400                         KASAN_KMALLOC_REDZONE);
401 }
402
403 void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
404 {
405         kasan_unpoison_shadow(object, cache->object_size);
406 }
407
408 void kasan_poison_object_data(struct kmem_cache *cache, void *object)
409 {
410         kasan_poison_shadow(object,
411                         round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
412                         KASAN_KMALLOC_REDZONE);
413 }
414
415 static inline int in_irqentry_text(unsigned long ptr)
416 {
417         return (ptr >= (unsigned long)&__irqentry_text_start &&
418                 ptr < (unsigned long)&__irqentry_text_end) ||
419                 (ptr >= (unsigned long)&__softirqentry_text_start &&
420                  ptr < (unsigned long)&__softirqentry_text_end);
421 }
422
423 static inline void filter_irq_stacks(struct stack_trace *trace)
424 {
425         int i;
426
427         if (!trace->nr_entries)
428                 return;
429         for (i = 0; i < trace->nr_entries; i++)
430                 if (in_irqentry_text(trace->entries[i])) {
431                         /* Include the irqentry function into the stack. */
432                         trace->nr_entries = i + 1;
433                         break;
434                 }
435 }
436
437 static inline depot_stack_handle_t save_stack(gfp_t flags)
438 {
439         unsigned long entries[KASAN_STACK_DEPTH];
440         struct stack_trace trace = {
441                 .nr_entries = 0,
442                 .entries = entries,
443                 .max_entries = KASAN_STACK_DEPTH,
444                 .skip = 0
445         };
446
447         save_stack_trace(&trace);
448         filter_irq_stacks(&trace);
449         if (trace.nr_entries != 0 &&
450             trace.entries[trace.nr_entries-1] == ULONG_MAX)
451                 trace.nr_entries--;
452
453         return depot_save_stack(&trace, flags);
454 }
455
456 static inline void set_track(struct kasan_track *track, gfp_t flags)
457 {
458         track->pid = current->pid;
459         track->stack = save_stack(flags);
460 }
461
462 struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
463                                         const void *object)
464 {
465         BUILD_BUG_ON(sizeof(struct kasan_alloc_meta) > 32);
466         return (void *)object + cache->kasan_info.alloc_meta_offset;
467 }
468
469 struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
470                                       const void *object)
471 {
472         BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
473         return (void *)object + cache->kasan_info.free_meta_offset;
474 }
475
476 void kasan_init_slab_obj(struct kmem_cache *cache, const void *object)
477 {
478         struct kasan_alloc_meta *alloc_info;
479
480         if (!(cache->flags & SLAB_KASAN))
481                 return;
482
483         alloc_info = get_alloc_info(cache, object);
484         __memset(alloc_info, 0, sizeof(*alloc_info));
485 }
486
487 void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
488 {
489         kasan_kmalloc(cache, object, cache->object_size, flags);
490 }
491
492 static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
493                               unsigned long ip, bool quarantine)
494 {
495         s8 shadow_byte;
496         unsigned long rounded_up_size;
497
498         if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) !=
499             object)) {
500                 kasan_report_invalid_free(object, ip);
501                 return true;
502         }
503
504         /* RCU slabs could be legally used after free within the RCU period */
505         if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
506                 return false;
507
508         shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
509         if (shadow_byte < 0 || shadow_byte >= KASAN_SHADOW_SCALE_SIZE) {
510                 kasan_report_invalid_free(object, ip);
511                 return true;
512         }
513
514         rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE);
515         kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
516
517         if (!quarantine || unlikely(!(cache->flags & SLAB_KASAN)))
518                 return false;
519
520         set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT);
521         quarantine_put(get_free_info(cache, object), cache);
522         return true;
523 }
524
525 bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
526 {
527         return __kasan_slab_free(cache, object, ip, true);
528 }
529
530 void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
531                    gfp_t flags)
532 {
533         unsigned long redzone_start;
534         unsigned long redzone_end;
535
536         if (gfpflags_allow_blocking(flags))
537                 quarantine_reduce();
538
539         if (unlikely(object == NULL))
540                 return;
541
542         redzone_start = round_up((unsigned long)(object + size),
543                                 KASAN_SHADOW_SCALE_SIZE);
544         redzone_end = round_up((unsigned long)object + cache->object_size,
545                                 KASAN_SHADOW_SCALE_SIZE);
546
547         kasan_unpoison_shadow(object, size);
548         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
549                 KASAN_KMALLOC_REDZONE);
550
551         if (cache->flags & SLAB_KASAN)
552                 set_track(&get_alloc_info(cache, object)->alloc_track, flags);
553 }
554 EXPORT_SYMBOL(kasan_kmalloc);
555
556 void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
557 {
558         struct page *page;
559         unsigned long redzone_start;
560         unsigned long redzone_end;
561
562         if (gfpflags_allow_blocking(flags))
563                 quarantine_reduce();
564
565         if (unlikely(ptr == NULL))
566                 return;
567
568         page = virt_to_page(ptr);
569         redzone_start = round_up((unsigned long)(ptr + size),
570                                 KASAN_SHADOW_SCALE_SIZE);
571         redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
572
573         kasan_unpoison_shadow(ptr, size);
574         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
575                 KASAN_PAGE_REDZONE);
576 }
577
578 void kasan_krealloc(const void *object, size_t size, gfp_t flags)
579 {
580         struct page *page;
581
582         if (unlikely(object == ZERO_SIZE_PTR))
583                 return;
584
585         page = virt_to_head_page(object);
586
587         if (unlikely(!PageSlab(page)))
588                 kasan_kmalloc_large(object, size, flags);
589         else
590                 kasan_kmalloc(page->slab_cache, object, size, flags);
591 }
592
593 void kasan_poison_kfree(void *ptr, unsigned long ip)
594 {
595         struct page *page;
596
597         page = virt_to_head_page(ptr);
598
599         if (unlikely(!PageSlab(page))) {
600                 if (ptr != page_address(page)) {
601                         kasan_report_invalid_free(ptr, ip);
602                         return;
603                 }
604                 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
605                                 KASAN_FREE_PAGE);
606         } else {
607                 __kasan_slab_free(page->slab_cache, ptr, ip, false);
608         }
609 }
610
611 void kasan_kfree_large(void *ptr, unsigned long ip)
612 {
613         if (ptr != page_address(virt_to_head_page(ptr)))
614                 kasan_report_invalid_free(ptr, ip);
615         /* The object will be poisoned by page_alloc. */
616 }
617
618 int kasan_module_alloc(void *addr, size_t size)
619 {
620         void *ret;
621         size_t shadow_size;
622         unsigned long shadow_start;
623
624         shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
625         shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
626                         PAGE_SIZE);
627
628         if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
629                 return -EINVAL;
630
631         ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
632                         shadow_start + shadow_size,
633                         GFP_KERNEL | __GFP_ZERO,
634                         PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
635                         __builtin_return_address(0));
636
637         if (ret) {
638                 find_vm_area(addr)->flags |= VM_KASAN;
639                 kmemleak_ignore(ret);
640                 return 0;
641         }
642
643         return -ENOMEM;
644 }
645
646 void kasan_free_shadow(const struct vm_struct *vm)
647 {
648         if (vm->flags & VM_KASAN)
649                 vfree(kasan_mem_to_shadow(vm->addr));
650 }
651
652 static void register_global(struct kasan_global *global)
653 {
654         size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
655
656         kasan_unpoison_shadow(global->beg, global->size);
657
658         kasan_poison_shadow(global->beg + aligned_size,
659                 global->size_with_redzone - aligned_size,
660                 KASAN_GLOBAL_REDZONE);
661 }
662
663 void __asan_register_globals(struct kasan_global *globals, size_t size)
664 {
665         int i;
666
667         for (i = 0; i < size; i++)
668                 register_global(&globals[i]);
669 }
670 EXPORT_SYMBOL(__asan_register_globals);
671
672 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
673 {
674 }
675 EXPORT_SYMBOL(__asan_unregister_globals);
676
677 #define DEFINE_ASAN_LOAD_STORE(size)                                    \
678         void __asan_load##size(unsigned long addr)                      \
679         {                                                               \
680                 check_memory_region_inline(addr, size, false, _RET_IP_);\
681         }                                                               \
682         EXPORT_SYMBOL(__asan_load##size);                               \
683         __alias(__asan_load##size)                                      \
684         void __asan_load##size##_noabort(unsigned long);                \
685         EXPORT_SYMBOL(__asan_load##size##_noabort);                     \
686         void __asan_store##size(unsigned long addr)                     \
687         {                                                               \
688                 check_memory_region_inline(addr, size, true, _RET_IP_); \
689         }                                                               \
690         EXPORT_SYMBOL(__asan_store##size);                              \
691         __alias(__asan_store##size)                                     \
692         void __asan_store##size##_noabort(unsigned long);               \
693         EXPORT_SYMBOL(__asan_store##size##_noabort)
694
695 DEFINE_ASAN_LOAD_STORE(1);
696 DEFINE_ASAN_LOAD_STORE(2);
697 DEFINE_ASAN_LOAD_STORE(4);
698 DEFINE_ASAN_LOAD_STORE(8);
699 DEFINE_ASAN_LOAD_STORE(16);
700
701 void __asan_loadN(unsigned long addr, size_t size)
702 {
703         check_memory_region(addr, size, false, _RET_IP_);
704 }
705 EXPORT_SYMBOL(__asan_loadN);
706
707 __alias(__asan_loadN)
708 void __asan_loadN_noabort(unsigned long, size_t);
709 EXPORT_SYMBOL(__asan_loadN_noabort);
710
711 void __asan_storeN(unsigned long addr, size_t size)
712 {
713         check_memory_region(addr, size, true, _RET_IP_);
714 }
715 EXPORT_SYMBOL(__asan_storeN);
716
717 __alias(__asan_storeN)
718 void __asan_storeN_noabort(unsigned long, size_t);
719 EXPORT_SYMBOL(__asan_storeN_noabort);
720
721 /* to shut up compiler complaints */
722 void __asan_handle_no_return(void) {}
723 EXPORT_SYMBOL(__asan_handle_no_return);
724
725 /* Emitted by compiler to poison large objects when they go out of scope. */
726 void __asan_poison_stack_memory(const void *addr, size_t size)
727 {
728         /*
729          * Addr is KASAN_SHADOW_SCALE_SIZE-aligned and the object is surrounded
730          * by redzones, so we simply round up size to simplify logic.
731          */
732         kasan_poison_shadow(addr, round_up(size, KASAN_SHADOW_SCALE_SIZE),
733                             KASAN_USE_AFTER_SCOPE);
734 }
735 EXPORT_SYMBOL(__asan_poison_stack_memory);
736
737 /* Emitted by compiler to unpoison large objects when they go into scope. */
738 void __asan_unpoison_stack_memory(const void *addr, size_t size)
739 {
740         kasan_unpoison_shadow(addr, size);
741 }
742 EXPORT_SYMBOL(__asan_unpoison_stack_memory);
743
744 /* Emitted by compiler to poison alloca()ed objects. */
745 void __asan_alloca_poison(unsigned long addr, size_t size)
746 {
747         size_t rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
748         size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
749                         rounded_up_size;
750         size_t rounded_down_size = round_down(size, KASAN_SHADOW_SCALE_SIZE);
751
752         const void *left_redzone = (const void *)(addr -
753                         KASAN_ALLOCA_REDZONE_SIZE);
754         const void *right_redzone = (const void *)(addr + rounded_up_size);
755
756         WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
757
758         kasan_unpoison_shadow((const void *)(addr + rounded_down_size),
759                               size - rounded_down_size);
760         kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
761                         KASAN_ALLOCA_LEFT);
762         kasan_poison_shadow(right_redzone,
763                         padding_size + KASAN_ALLOCA_REDZONE_SIZE,
764                         KASAN_ALLOCA_RIGHT);
765 }
766 EXPORT_SYMBOL(__asan_alloca_poison);
767
768 /* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
769 void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
770 {
771         if (unlikely(!stack_top || stack_top > stack_bottom))
772                 return;
773
774         kasan_unpoison_shadow(stack_top, stack_bottom - stack_top);
775 }
776 EXPORT_SYMBOL(__asan_allocas_unpoison);
777
778 /* Emitted by the compiler to [un]poison local variables. */
779 #define DEFINE_ASAN_SET_SHADOW(byte) \
780         void __asan_set_shadow_##byte(const void *addr, size_t size)    \
781         {                                                               \
782                 __memset((void *)addr, 0x##byte, size);                 \
783         }                                                               \
784         EXPORT_SYMBOL(__asan_set_shadow_##byte)
785
786 DEFINE_ASAN_SET_SHADOW(00);
787 DEFINE_ASAN_SET_SHADOW(f1);
788 DEFINE_ASAN_SET_SHADOW(f2);
789 DEFINE_ASAN_SET_SHADOW(f3);
790 DEFINE_ASAN_SET_SHADOW(f5);
791 DEFINE_ASAN_SET_SHADOW(f8);
792
793 #ifdef CONFIG_MEMORY_HOTPLUG
794 static int __meminit kasan_mem_notifier(struct notifier_block *nb,
795                         unsigned long action, void *data)
796 {
797         struct memory_notify *mem_data = data;
798         unsigned long nr_shadow_pages, start_kaddr, shadow_start;
799         unsigned long shadow_end, shadow_size;
800
801         nr_shadow_pages = mem_data->nr_pages >> KASAN_SHADOW_SCALE_SHIFT;
802         start_kaddr = (unsigned long)pfn_to_kaddr(mem_data->start_pfn);
803         shadow_start = (unsigned long)kasan_mem_to_shadow((void *)start_kaddr);
804         shadow_size = nr_shadow_pages << PAGE_SHIFT;
805         shadow_end = shadow_start + shadow_size;
806
807         if (WARN_ON(mem_data->nr_pages % KASAN_SHADOW_SCALE_SIZE) ||
808                 WARN_ON(start_kaddr % (KASAN_SHADOW_SCALE_SIZE << PAGE_SHIFT)))
809                 return NOTIFY_BAD;
810
811         switch (action) {
812         case MEM_GOING_ONLINE: {
813                 void *ret;
814
815                 ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start,
816                                         shadow_end, GFP_KERNEL,
817                                         PAGE_KERNEL, VM_NO_GUARD,
818                                         pfn_to_nid(mem_data->start_pfn),
819                                         __builtin_return_address(0));
820                 if (!ret)
821                         return NOTIFY_BAD;
822
823                 kmemleak_ignore(ret);
824                 return NOTIFY_OK;
825         }
826         case MEM_OFFLINE:
827                 vfree((void *)shadow_start);
828         }
829
830         return NOTIFY_OK;
831 }
832
833 static int __init kasan_memhotplug_init(void)
834 {
835         hotplug_memory_notifier(kasan_mem_notifier, 0);
836
837         return 0;
838 }
839
840 module_init(kasan_memhotplug_init);
841 #endif