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                         unsigned long *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 void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
 493 {
 494         unsigned long size = cache->object_size;
 495         unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
 496
 497         /* RCU slabs could be legally used after free within the RCU period */
 498         if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
 499                 return;
 500
 501         kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
 502 }
 503
 504 bool kasan_slab_free(struct kmem_cache *cache, void *object)
 505 {
 506         s8 shadow_byte;
 507
 508         /* RCU slabs could be legally used after free within the RCU period */
 509         if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
 510                 return false;
 511
 512         shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
 513         if (shadow_byte < 0 || shadow_byte >= KASAN_SHADOW_SCALE_SIZE) {
 514                 kasan_report_double_free(cache, object,
 515                                 __builtin_return_address(1));
 516                 return true;
 517         }
 518
 519         kasan_poison_slab_free(cache, object);
 520
 521         if (unlikely(!(cache->flags & SLAB_KASAN)))
 522                 return false;
 523
 524         set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT);
 525         quarantine_put(get_free_info(cache, object), cache);
 526         return true;
 527 }
 528
 529 void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
 530                    gfp_t flags)
 531 {
 532         unsigned long redzone_start;
 533         unsigned long redzone_end;
 534
 535         if (gfpflags_allow_blocking(flags))
 536                 quarantine_reduce();
 537
 538         if (unlikely(object == NULL))
 539                 return;
 540
 541         redzone_start = round_up((unsigned long)(object + size),
 542                                 KASAN_SHADOW_SCALE_SIZE);
 543         redzone_end = round_up((unsigned long)object + cache->object_size,
 544                                 KASAN_SHADOW_SCALE_SIZE);
 545
 546         kasan_unpoison_shadow(object, size);
 547         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
 548                 KASAN_KMALLOC_REDZONE);
 549
 550         if (cache->flags & SLAB_KASAN)
 551                 set_track(&get_alloc_info(cache, object)->alloc_track, flags);
 552 }
 553 EXPORT_SYMBOL(kasan_kmalloc);
 554
 555 void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
 556 {
 557         struct page *page;
 558         unsigned long redzone_start;
 559         unsigned long redzone_end;
 560
 561         if (gfpflags_allow_blocking(flags))
 562                 quarantine_reduce();
 563
 564         if (unlikely(ptr == NULL))
 565                 return;
 566
 567         page = virt_to_page(ptr);
 568         redzone_start = round_up((unsigned long)(ptr + size),
 569                                 KASAN_SHADOW_SCALE_SIZE);
 570         redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
 571
 572         kasan_unpoison_shadow(ptr, size);
 573         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
 574                 KASAN_PAGE_REDZONE);
 575 }
 576
 577 void kasan_krealloc(const void *object, size_t size, gfp_t flags)
 578 {
 579         struct page *page;
 580
 581         if (unlikely(object == ZERO_SIZE_PTR))
 582                 return;
 583
 584         page = virt_to_head_page(object);
 585
 586         if (unlikely(!PageSlab(page)))
 587                 kasan_kmalloc_large(object, size, flags);
 588         else
 589                 kasan_kmalloc(page->slab_cache, object, size, flags);
 590 }
 591
 592 void kasan_poison_kfree(void *ptr)
 593 {
 594         struct page *page;
 595
 596         page = virt_to_head_page(ptr);
 597
 598         if (unlikely(!PageSlab(page)))
 599                 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
 600                                 KASAN_FREE_PAGE);
 601         else
 602                 kasan_poison_slab_free(page->slab_cache, ptr);
 603 }
 604
 605 void kasan_kfree_large(const void *ptr)
 606 {
 607         struct page *page = virt_to_page(ptr);
 608
 609         kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
 610                         KASAN_FREE_PAGE);
 611 }
 612
 613 int kasan_module_alloc(void *addr, size_t size)
 614 {
 615         void *ret;
 616         size_t scaled_size;
 617         size_t shadow_size;
 618         unsigned long shadow_start;
 619
 620         shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
 621         scaled_size = (size + KASAN_SHADOW_MASK) >> KASAN_SHADOW_SCALE_SHIFT;
 622         shadow_size = round_up(scaled_size, PAGE_SIZE);
 623
 624         if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
 625                 return -EINVAL;
 626
 627         ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
 628                         shadow_start + shadow_size,
 629                         GFP_KERNEL | __GFP_ZERO,
 630                         PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
 631                         __builtin_return_address(0));
 632
 633         if (ret) {
 634                 find_vm_area(addr)->flags |= VM_KASAN;
 635                 kmemleak_ignore(ret);
 636                 return 0;
 637         }
 638
 639         return -ENOMEM;
 640 }
 641
 642 void kasan_free_shadow(const struct vm_struct *vm)
 643 {
 644         if (vm->flags & VM_KASAN)
 645                 vfree(kasan_mem_to_shadow(vm->addr));
 646 }
 647
 648 static void register_global(struct kasan_global *global)
 649 {
 650         size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
 651
 652         kasan_unpoison_shadow(global->beg, global->size);
 653
 654         kasan_poison_shadow(global->beg + aligned_size,
 655                 global->size_with_redzone - aligned_size,
 656                 KASAN_GLOBAL_REDZONE);
 657 }
 658
 659 void __asan_register_globals(struct kasan_global *globals, size_t size)
 660 {
 661         int i;
 662
 663         for (i = 0; i < size; i++)
 664                 register_global(&globals[i]);
 665 }
 666 EXPORT_SYMBOL(__asan_register_globals);
 667
 668 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
 669 {
 670 }
 671 EXPORT_SYMBOL(__asan_unregister_globals);
 672
 673 #define DEFINE_ASAN_LOAD_STORE(size)                                    \
 674         void __asan_load##size(unsigned long addr)                      \
 675         {                                                               \
 676                 check_memory_region_inline(addr, size, false, _RET_IP_);\
 677         }                                                               \
 678         EXPORT_SYMBOL(__asan_load##size);                               \
 679         __alias(__asan_load##size)                                      \
 680         void __asan_load##size##_noabort(unsigned long);                \
 681         EXPORT_SYMBOL(__asan_load##size##_noabort);                     \
 682         void __asan_store##size(unsigned long addr)                     \
 683         {                                                               \
 684                 check_memory_region_inline(addr, size, true, _RET_IP_); \
 685         }                                                               \
 686         EXPORT_SYMBOL(__asan_store##size);                              \
 687         __alias(__asan_store##size)                                     \
 688         void __asan_store##size##_noabort(unsigned long);               \
 689         EXPORT_SYMBOL(__asan_store##size##_noabort)
 690
 691 DEFINE_ASAN_LOAD_STORE(1);
 692 DEFINE_ASAN_LOAD_STORE(2);
 693 DEFINE_ASAN_LOAD_STORE(4);
 694 DEFINE_ASAN_LOAD_STORE(8);
 695 DEFINE_ASAN_LOAD_STORE(16);
 696
 697 void __asan_loadN(unsigned long addr, size_t size)
 698 {
 699         check_memory_region(addr, size, false, _RET_IP_);
 700 }
 701 EXPORT_SYMBOL(__asan_loadN);
 702
 703 __alias(__asan_loadN)
 704 void __asan_loadN_noabort(unsigned long, size_t);
 705 EXPORT_SYMBOL(__asan_loadN_noabort);
 706
 707 void __asan_storeN(unsigned long addr, size_t size)
 708 {
 709         check_memory_region(addr, size, true, _RET_IP_);
 710 }
 711 EXPORT_SYMBOL(__asan_storeN);
 712
 713 __alias(__asan_storeN)
 714 void __asan_storeN_noabort(unsigned long, size_t);
 715 EXPORT_SYMBOL(__asan_storeN_noabort);
 716
 717 /* to shut up compiler complaints */
 718 void __asan_handle_no_return(void) {}
 719 EXPORT_SYMBOL(__asan_handle_no_return);
 720
 721 /* Emitted by compiler to poison large objects when they go out of scope. */
 722 void __asan_poison_stack_memory(const void *addr, size_t size)
 723 {
 724         /*
 725          * Addr is KASAN_SHADOW_SCALE_SIZE-aligned and the object is surrounded
 726          * by redzones, so we simply round up size to simplify logic.
 727          */
 728         kasan_poison_shadow(addr, round_up(size, KASAN_SHADOW_SCALE_SIZE),
 729                             KASAN_USE_AFTER_SCOPE);
 730 }
 731 EXPORT_SYMBOL(__asan_poison_stack_memory);
 732
 733 /* Emitted by compiler to unpoison large objects when they go into scope. */
 734 void __asan_unpoison_stack_memory(const void *addr, size_t size)
 735 {
 736         kasan_unpoison_shadow(addr, size);
 737 }
 738 EXPORT_SYMBOL(__asan_unpoison_stack_memory);
 739
 740 #ifdef CONFIG_MEMORY_HOTPLUG
 741 static bool shadow_mapped(unsigned long addr)
 742 {
 743         pgd_t *pgd = pgd_offset_k(addr);
 744         p4d_t *p4d;
 745         pud_t *pud;
 746         pmd_t *pmd;
 747         pte_t *pte;
 748
 749         if (pgd_none(*pgd))
 750                 return false;
 751         p4d = p4d_offset(pgd, addr);
 752         if (p4d_none(*p4d))
 753                 return false;
 754         pud = pud_offset(p4d, addr);
 755         if (pud_none(*pud))
 756                 return false;
 757
 758         /*
 759          * We can't use pud_large() or pud_huge(), the first one is
 760          * arch-specific, the last one depends on HUGETLB_PAGE.  So let's abuse
 761          * pud_bad(), if pud is bad then it's bad because it's huge.
 762          */
 763         if (pud_bad(*pud))
 764                 return true;
 765         pmd = pmd_offset(pud, addr);
 766         if (pmd_none(*pmd))
 767                 return false;
 768
 769         if (pmd_bad(*pmd))
 770                 return true;
 771         pte = pte_offset_kernel(pmd, addr);
 772         return !pte_none(*pte);
 773 }
 774
 775 static int __meminit kasan_mem_notifier(struct notifier_block *nb,
 776                         unsigned long action, void *data)
 777 {
 778         struct memory_notify *mem_data = data;
 779         unsigned long nr_shadow_pages, start_kaddr, shadow_start;
 780         unsigned long shadow_end, shadow_size;
 781
 782         nr_shadow_pages = mem_data->nr_pages >> KASAN_SHADOW_SCALE_SHIFT;
 783         start_kaddr = (unsigned long)pfn_to_kaddr(mem_data->start_pfn);
 784         shadow_start = (unsigned long)kasan_mem_to_shadow((void *)start_kaddr);
 785         shadow_size = nr_shadow_pages << PAGE_SHIFT;
 786         shadow_end = shadow_start + shadow_size;
 787
 788         if (WARN_ON(mem_data->nr_pages % KASAN_SHADOW_SCALE_SIZE) ||
 789                 WARN_ON(start_kaddr % (KASAN_SHADOW_SCALE_SIZE << PAGE_SHIFT)))
 790                 return NOTIFY_BAD;
 791
 792         switch (action) {
 793         case MEM_GOING_ONLINE: {
 794                 void *ret;
 795
 796                 /*
 797                  * If shadow is mapped already than it must have been mapped
 798                  * during the boot. This could happen if we onlining previously
 799                  * offlined memory.
 800                  */
 801                 if (shadow_mapped(shadow_start))
 802                         return NOTIFY_OK;
 803
 804                 ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start,
 805                                         shadow_end, GFP_KERNEL,
 806                                         PAGE_KERNEL, VM_NO_GUARD,
 807                                         pfn_to_nid(mem_data->start_pfn),
 808                                         __builtin_return_address(0));
 809                 if (!ret)
 810                         return NOTIFY_BAD;
 811
 812                 kmemleak_ignore(ret);
 813                 return NOTIFY_OK;
 814         }
 815         case MEM_CANCEL_ONLINE:
 816         case MEM_OFFLINE: {
 817                 struct vm_struct *vm;
 818
 819                 /*
 820                  * shadow_start was either mapped during boot by kasan_init()
 821                  * or during memory online by __vmalloc_node_range().
 822                  * In the latter case we can use vfree() to free shadow.
 823                  * Non-NULL result of the find_vm_area() will tell us if
 824                  * that was the second case.
 825                  *
 826                  * Currently it's not possible to free shadow mapped
 827                  * during boot by kasan_init(). It's because the code
 828                  * to do that hasn't been written yet. So we'll just
 829                  * leak the memory.
 830                  */
 831                 vm = find_vm_area((void *)shadow_start);
 832                 if (vm)
 833                         vfree((void *)shadow_start);
 834         }
 835         }
 836
 837         return NOTIFY_OK;
 838 }
 839
 840 static int __init kasan_memhotplug_init(void)
 841 {
 842         hotplug_memory_notifier(kasan_mem_notifier, 0);
 843
 844         return 0;
 845 }
 846
 847 core_initcall(kasan_memhotplug_init);
 848 #endif