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/slab.h>
  33 #include <linux/stacktrace.h>
  34 #include <linux/string.h>
  35 #include <linux/types.h>
  36 #include <linux/vmalloc.h>
  37 #include <linux/bug.h>
  38
  39 #include "kasan.h"
  40 #include "../slab.h"
  41
  42 /*
  43  * Poisons the shadow memory for 'size' bytes starting from 'addr'.
  44  * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
  45  */
  46 static void kasan_poison_shadow(const void *address, size_t size, u8 value)
  47 {
  48         void *shadow_start, *shadow_end;
  49
  50         shadow_start = kasan_mem_to_shadow(address);
  51         shadow_end = kasan_mem_to_shadow(address + size);
  52
  53         memset(shadow_start, value, shadow_end - shadow_start);
  54 }
  55
  56 void kasan_unpoison_shadow(const void *address, size_t size)
  57 {
  58         kasan_poison_shadow(address, size, 0);
  59
  60         if (size & KASAN_SHADOW_MASK) {
  61                 u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
  62                 *shadow = size & KASAN_SHADOW_MASK;
  63         }
  64 }
  65
  66 static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
  67 {
  68         void *base = task_stack_page(task);
  69         size_t size = sp - base;
  70
  71         kasan_unpoison_shadow(base, size);
  72 }
  73
  74 /* Unpoison the entire stack for a task. */
  75 void kasan_unpoison_task_stack(struct task_struct *task)
  76 {
  77         __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE);
  78 }
  79
  80 /* Unpoison the stack for the current task beyond a watermark sp value. */
  81 asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
  82 {
  83         __kasan_unpoison_stack(current, watermark);
  84 }
  85
  86 /*
  87  * Clear all poison for the region between the current SP and a provided
  88  * watermark value, as is sometimes required prior to hand-crafted asm function
  89  * returns in the middle of functions.
  90  */
  91 void kasan_unpoison_stack_above_sp_to(const void *watermark)
  92 {
  93         const void *sp = __builtin_frame_address(0);
  94         size_t size = watermark - sp;
  95
  96         if (WARN_ON(sp > watermark))
  97                 return;
  98         kasan_unpoison_shadow(sp, size);
  99 }
 100
 101 /*
 102  * All functions below always inlined so compiler could
 103  * perform better optimizations in each of __asan_loadX/__assn_storeX
 104  * depending on memory access size X.
 105  */
 106
 107 static __always_inline bool memory_is_poisoned_1(unsigned long addr)
 108 {
 109         s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
 110
 111         if (unlikely(shadow_value)) {
 112                 s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
 113                 return unlikely(last_accessible_byte >= shadow_value);
 114         }
 115
 116         return false;
 117 }
 118
 119 static __always_inline bool memory_is_poisoned_2(unsigned long addr)
 120 {
 121         u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
 122
 123         if (unlikely(*shadow_addr)) {
 124                 if (memory_is_poisoned_1(addr + 1))
 125                         return true;
 126
 127                 /*
 128                  * If single shadow byte covers 2-byte access, we don't
 129                  * need to do anything more. Otherwise, test the first
 130                  * shadow byte.
 131                  */
 132                 if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
 133                         return false;
 134
 135                 return unlikely(*(u8 *)shadow_addr);
 136         }
 137
 138         return false;
 139 }
 140
 141 static __always_inline bool memory_is_poisoned_4(unsigned long addr)
 142 {
 143         u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
 144
 145         if (unlikely(*shadow_addr)) {
 146                 if (memory_is_poisoned_1(addr + 3))
 147                         return true;
 148
 149                 /*
 150                  * If single shadow byte covers 4-byte access, we don't
 151                  * need to do anything more. Otherwise, test the first
 152                  * shadow byte.
 153                  */
 154                 if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
 155                         return false;
 156
 157                 return unlikely(*(u8 *)shadow_addr);
 158         }
 159
 160         return false;
 161 }
 162
 163 static __always_inline bool memory_is_poisoned_8(unsigned long addr)
 164 {
 165         u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
 166
 167         if (unlikely(*shadow_addr)) {
 168                 if (memory_is_poisoned_1(addr + 7))
 169                         return true;
 170
 171                 /*
 172                  * If single shadow byte covers 8-byte access, we don't
 173                  * need to do anything more. Otherwise, test the first
 174                  * shadow byte.
 175                  */
 176                 if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
 177                         return false;
 178
 179                 return unlikely(*(u8 *)shadow_addr);
 180         }
 181
 182         return false;
 183 }
 184
 185 static __always_inline bool memory_is_poisoned_16(unsigned long addr)
 186 {
 187         u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr);
 188
 189         if (unlikely(*shadow_addr)) {
 190                 u16 shadow_first_bytes = *(u16 *)shadow_addr;
 191
 192                 if (unlikely(shadow_first_bytes))
 193                         return true;
 194
 195                 /*
 196                  * If two shadow bytes covers 16-byte access, we don't
 197                  * need to do anything more. Otherwise, test the last
 198                  * shadow byte.
 199                  */
 200                 if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
 201                         return false;
 202
 203                 return memory_is_poisoned_1(addr + 15);
 204         }
 205
 206         return false;
 207 }
 208
 209 static __always_inline unsigned long bytes_is_zero(const u8 *start,
 210                                         size_t size)
 211 {
 212         while (size) {
 213                 if (unlikely(*start))
 214                         return (unsigned long)start;
 215                 start++;
 216                 size--;
 217         }
 218
 219         return 0;
 220 }
 221
 222 static __always_inline unsigned long memory_is_zero(const void *start,
 223                                                 const void *end)
 224 {
 225         unsigned int words;
 226         unsigned long ret;
 227         unsigned int prefix = (unsigned long)start % 8;
 228
 229         if (end - start <= 16)
 230                 return bytes_is_zero(start, end - start);
 231
 232         if (prefix) {
 233                 prefix = 8 - prefix;
 234                 ret = bytes_is_zero(start, prefix);
 235                 if (unlikely(ret))
 236                         return ret;
 237                 start += prefix;
 238         }
 239
 240         words = (end - start) / 8;
 241         while (words) {
 242                 if (unlikely(*(u64 *)start))
 243                         return bytes_is_zero(start, 8);
 244                 start += 8;
 245                 words--;
 246         }
 247
 248         return bytes_is_zero(start, (end - start) % 8);
 249 }
 250
 251 static __always_inline bool memory_is_poisoned_n(unsigned long addr,
 252                                                 size_t size)
 253 {
 254         unsigned long ret;
 255
 256         ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
 257                         kasan_mem_to_shadow((void *)addr + size - 1) + 1);
 258
 259         if (unlikely(ret)) {
 260                 unsigned long last_byte = addr + size - 1;
 261                 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
 262
 263                 if (unlikely(ret != (unsigned long)last_shadow ||
 264                         ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
 265                         return true;
 266         }
 267         return false;
 268 }
 269
 270 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
 271 {
 272         if (__builtin_constant_p(size)) {
 273                 switch (size) {
 274                 case 1:
 275                         return memory_is_poisoned_1(addr);
 276                 case 2:
 277                         return memory_is_poisoned_2(addr);
 278                 case 4:
 279                         return memory_is_poisoned_4(addr);
 280                 case 8:
 281                         return memory_is_poisoned_8(addr);
 282                 case 16:
 283                         return memory_is_poisoned_16(addr);
 284                 default:
 285                         BUILD_BUG();
 286                 }
 287         }
 288
 289         return memory_is_poisoned_n(addr, size);
 290 }
 291
 292 static __always_inline void check_memory_region_inline(unsigned long addr,
 293                                                 size_t size, bool write,
 294                                                 unsigned long ret_ip)
 295 {
 296         if (unlikely(size == 0))
 297                 return;
 298
 299         if (unlikely((void *)addr <
 300                 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
 301                 kasan_report(addr, size, write, ret_ip);
 302                 return;
 303         }
 304
 305         if (likely(!memory_is_poisoned(addr, size)))
 306                 return;
 307
 308         kasan_report(addr, size, write, ret_ip);
 309 }
 310
 311 static void check_memory_region(unsigned long addr,
 312                                 size_t size, bool write,
 313                                 unsigned long ret_ip)
 314 {
 315         check_memory_region_inline(addr, size, write, ret_ip);
 316 }
 317
 318 void kasan_check_read(const void *p, unsigned int size)
 319 {
 320         check_memory_region((unsigned long)p, size, false, _RET_IP_);
 321 }
 322 EXPORT_SYMBOL(kasan_check_read);
 323
 324 void kasan_check_write(const void *p, unsigned int size)
 325 {
 326         check_memory_region((unsigned long)p, size, true, _RET_IP_);
 327 }
 328 EXPORT_SYMBOL(kasan_check_write);
 329
 330 #undef memset
 331 void *memset(void *addr, int c, size_t len)
 332 {
 333         check_memory_region((unsigned long)addr, len, true, _RET_IP_);
 334
 335         return __memset(addr, c, len);
 336 }
 337
 338 #undef memmove
 339 void *memmove(void *dest, const void *src, size_t len)
 340 {
 341         check_memory_region((unsigned long)src, len, false, _RET_IP_);
 342         check_memory_region((unsigned long)dest, len, true, _RET_IP_);
 343
 344         return __memmove(dest, src, len);
 345 }
 346
 347 #undef memcpy
 348 void *memcpy(void *dest, const void *src, size_t len)
 349 {
 350         check_memory_region((unsigned long)src, len, false, _RET_IP_);
 351         check_memory_region((unsigned long)dest, len, true, _RET_IP_);
 352
 353         return __memcpy(dest, src, len);
 354 }
 355
 356 void kasan_alloc_pages(struct page *page, unsigned int order)
 357 {
 358         if (likely(!PageHighMem(page)))
 359                 kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
 360 }
 361
 362 void kasan_free_pages(struct page *page, unsigned int order)
 363 {
 364         if (likely(!PageHighMem(page)))
 365                 kasan_poison_shadow(page_address(page),
 366                                 PAGE_SIZE << order,
 367                                 KASAN_FREE_PAGE);
 368 }
 369
 370 /*
 371  * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
 372  * For larger allocations larger redzones are used.
 373  */
 374 static size_t optimal_redzone(size_t object_size)
 375 {
 376         int rz =
 377                 object_size <= 64        - 16   ? 16 :
 378                 object_size <= 128       - 32   ? 32 :
 379                 object_size <= 512       - 64   ? 64 :
 380                 object_size <= 4096      - 128  ? 128 :
 381                 object_size <= (1 << 14) - 256  ? 256 :
 382                 object_size <= (1 << 15) - 512  ? 512 :
 383                 object_size <= (1 << 16) - 1024 ? 1024 : 2048;
 384         return rz;
 385 }
 386
 387 void kasan_cache_create(struct kmem_cache *cache, size_t *size,
 388                         unsigned long *flags)
 389 {
 390         int redzone_adjust;
 391         int orig_size = *size;
 392
 393         /* Add alloc meta. */
 394         cache->kasan_info.alloc_meta_offset = *size;
 395         *size += sizeof(struct kasan_alloc_meta);
 396
 397         /* Add free meta. */
 398         if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor ||
 399             cache->object_size < sizeof(struct kasan_free_meta)) {
 400                 cache->kasan_info.free_meta_offset = *size;
 401                 *size += sizeof(struct kasan_free_meta);
 402         }
 403         redzone_adjust = optimal_redzone(cache->object_size) -
 404                 (*size - cache->object_size);
 405
 406         if (redzone_adjust > 0)
 407                 *size += redzone_adjust;
 408
 409         *size = min(KMALLOC_MAX_SIZE, max(*size, cache->object_size +
 410                                         optimal_redzone(cache->object_size)));
 411
 412         /*
 413          * If the metadata doesn't fit, don't enable KASAN at all.
 414          */
 415         if (*size <= cache->kasan_info.alloc_meta_offset ||
 416                         *size <= cache->kasan_info.free_meta_offset) {
 417                 cache->kasan_info.alloc_meta_offset = 0;
 418                 cache->kasan_info.free_meta_offset = 0;
 419                 *size = orig_size;
 420                 return;
 421         }
 422
 423         *flags |= SLAB_KASAN;
 424 }
 425
 426 void kasan_cache_shrink(struct kmem_cache *cache)
 427 {
 428         quarantine_remove_cache(cache);
 429 }
 430
 431 void kasan_cache_destroy(struct kmem_cache *cache)
 432 {
 433         quarantine_remove_cache(cache);
 434 }
 435
 436 size_t kasan_metadata_size(struct kmem_cache *cache)
 437 {
 438         return (cache->kasan_info.alloc_meta_offset ?
 439                 sizeof(struct kasan_alloc_meta) : 0) +
 440                 (cache->kasan_info.free_meta_offset ?
 441                 sizeof(struct kasan_free_meta) : 0);
 442 }
 443
 444 void kasan_poison_slab(struct page *page)
 445 {
 446         kasan_poison_shadow(page_address(page),
 447                         PAGE_SIZE << compound_order(page),
 448                         KASAN_KMALLOC_REDZONE);
 449 }
 450
 451 void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
 452 {
 453         kasan_unpoison_shadow(object, cache->object_size);
 454 }
 455
 456 void kasan_poison_object_data(struct kmem_cache *cache, void *object)
 457 {
 458         kasan_poison_shadow(object,
 459                         round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
 460                         KASAN_KMALLOC_REDZONE);
 461 }
 462
 463 static inline int in_irqentry_text(unsigned long ptr)
 464 {
 465         return (ptr >= (unsigned long)&__irqentry_text_start &&
 466                 ptr < (unsigned long)&__irqentry_text_end) ||
 467                 (ptr >= (unsigned long)&__softirqentry_text_start &&
 468                  ptr < (unsigned long)&__softirqentry_text_end);
 469 }
 470
 471 static inline void filter_irq_stacks(struct stack_trace *trace)
 472 {
 473         int i;
 474
 475         if (!trace->nr_entries)
 476                 return;
 477         for (i = 0; i < trace->nr_entries; i++)
 478                 if (in_irqentry_text(trace->entries[i])) {
 479                         /* Include the irqentry function into the stack. */
 480                         trace->nr_entries = i + 1;
 481                         break;
 482                 }
 483 }
 484
 485 static inline depot_stack_handle_t save_stack(gfp_t flags)
 486 {
 487         unsigned long entries[KASAN_STACK_DEPTH];
 488         struct stack_trace trace = {
 489                 .nr_entries = 0,
 490                 .entries = entries,
 491                 .max_entries = KASAN_STACK_DEPTH,
 492                 .skip = 0
 493         };
 494
 495         save_stack_trace(&trace);
 496         filter_irq_stacks(&trace);
 497         if (trace.nr_entries != 0 &&
 498             trace.entries[trace.nr_entries-1] == ULONG_MAX)
 499                 trace.nr_entries--;
 500
 501         return depot_save_stack(&trace, flags);
 502 }
 503
 504 static inline void set_track(struct kasan_track *track, gfp_t flags)
 505 {
 506         track->pid = current->pid;
 507         track->stack = save_stack(flags);
 508 }
 509
 510 struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
 511                                         const void *object)
 512 {
 513         BUILD_BUG_ON(sizeof(struct kasan_alloc_meta) > 32);
 514         return (void *)object + cache->kasan_info.alloc_meta_offset;
 515 }
 516
 517 struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
 518                                       const void *object)
 519 {
 520         BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
 521         return (void *)object + cache->kasan_info.free_meta_offset;
 522 }
 523
 524 void kasan_init_slab_obj(struct kmem_cache *cache, const void *object)
 525 {
 526         struct kasan_alloc_meta *alloc_info;
 527
 528         if (!(cache->flags & SLAB_KASAN))
 529                 return;
 530
 531         alloc_info = get_alloc_info(cache, object);
 532         __memset(alloc_info, 0, sizeof(*alloc_info));
 533 }
 534
 535 void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
 536 {
 537         kasan_kmalloc(cache, object, cache->object_size, flags);
 538 }
 539
 540 static void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
 541 {
 542         unsigned long size = cache->object_size;
 543         unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
 544
 545         /* RCU slabs could be legally used after free within the RCU period */
 546         if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
 547                 return;
 548
 549         kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
 550 }
 551
 552 bool kasan_slab_free(struct kmem_cache *cache, void *object)
 553 {
 554         s8 shadow_byte;
 555
 556         /* RCU slabs could be legally used after free within the RCU period */
 557         if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
 558                 return false;
 559
 560         shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
 561         if (shadow_byte < 0 || shadow_byte >= KASAN_SHADOW_SCALE_SIZE) {
 562                 kasan_report_double_free(cache, object, shadow_byte);
 563                 return true;
 564         }
 565
 566         kasan_poison_slab_free(cache, object);
 567
 568         if (unlikely(!(cache->flags & SLAB_KASAN)))
 569                 return false;
 570
 571         set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT);
 572         quarantine_put(get_free_info(cache, object), cache);
 573         return true;
 574 }
 575
 576 void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
 577                    gfp_t flags)
 578 {
 579         unsigned long redzone_start;
 580         unsigned long redzone_end;
 581
 582         if (gfpflags_allow_blocking(flags))
 583                 quarantine_reduce();
 584
 585         if (unlikely(object == NULL))
 586                 return;
 587
 588         redzone_start = round_up((unsigned long)(object + size),
 589                                 KASAN_SHADOW_SCALE_SIZE);
 590         redzone_end = round_up((unsigned long)object + cache->object_size,
 591                                 KASAN_SHADOW_SCALE_SIZE);
 592
 593         kasan_unpoison_shadow(object, size);
 594         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
 595                 KASAN_KMALLOC_REDZONE);
 596
 597         if (cache->flags & SLAB_KASAN)
 598                 set_track(&get_alloc_info(cache, object)->alloc_track, flags);
 599 }
 600 EXPORT_SYMBOL(kasan_kmalloc);
 601
 602 void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
 603 {
 604         struct page *page;
 605         unsigned long redzone_start;
 606         unsigned long redzone_end;
 607
 608         if (gfpflags_allow_blocking(flags))
 609                 quarantine_reduce();
 610
 611         if (unlikely(ptr == NULL))
 612                 return;
 613
 614         page = virt_to_page(ptr);
 615         redzone_start = round_up((unsigned long)(ptr + size),
 616                                 KASAN_SHADOW_SCALE_SIZE);
 617         redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
 618
 619         kasan_unpoison_shadow(ptr, size);
 620         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
 621                 KASAN_PAGE_REDZONE);
 622 }
 623
 624 void kasan_krealloc(const void *object, size_t size, gfp_t flags)
 625 {
 626         struct page *page;
 627
 628         if (unlikely(object == ZERO_SIZE_PTR))
 629                 return;
 630
 631         page = virt_to_head_page(object);
 632
 633         if (unlikely(!PageSlab(page)))
 634                 kasan_kmalloc_large(object, size, flags);
 635         else
 636                 kasan_kmalloc(page->slab_cache, object, size, flags);
 637 }
 638
 639 void kasan_poison_kfree(void *ptr)
 640 {
 641         struct page *page;
 642
 643         page = virt_to_head_page(ptr);
 644
 645         if (unlikely(!PageSlab(page)))
 646                 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
 647                                 KASAN_FREE_PAGE);
 648         else
 649                 kasan_poison_slab_free(page->slab_cache, ptr);
 650 }
 651
 652 void kasan_kfree_large(const void *ptr)
 653 {
 654         struct page *page = virt_to_page(ptr);
 655
 656         kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
 657                         KASAN_FREE_PAGE);
 658 }
 659
 660 int kasan_module_alloc(void *addr, size_t size)
 661 {
 662         void *ret;
 663         size_t shadow_size;
 664         unsigned long shadow_start;
 665
 666         shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
 667         shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
 668                         PAGE_SIZE);
 669
 670         if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
 671                 return -EINVAL;
 672
 673         ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
 674                         shadow_start + shadow_size,
 675                         GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 676                         PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
 677                         __builtin_return_address(0));
 678
 679         if (ret) {
 680                 find_vm_area(addr)->flags |= VM_KASAN;
 681                 kmemleak_ignore(ret);
 682                 return 0;
 683         }
 684
 685         return -ENOMEM;
 686 }
 687
 688 void kasan_free_shadow(const struct vm_struct *vm)
 689 {
 690         if (vm->flags & VM_KASAN)
 691                 vfree(kasan_mem_to_shadow(vm->addr));
 692 }
 693
 694 static void register_global(struct kasan_global *global)
 695 {
 696         size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
 697
 698         kasan_unpoison_shadow(global->beg, global->size);
 699
 700         kasan_poison_shadow(global->beg + aligned_size,
 701                 global->size_with_redzone - aligned_size,
 702                 KASAN_GLOBAL_REDZONE);
 703 }
 704
 705 void __asan_register_globals(struct kasan_global *globals, size_t size)
 706 {
 707         int i;
 708
 709         for (i = 0; i < size; i++)
 710                 register_global(&globals[i]);
 711 }
 712 EXPORT_SYMBOL(__asan_register_globals);
 713
 714 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
 715 {
 716 }
 717 EXPORT_SYMBOL(__asan_unregister_globals);
 718
 719 #define DEFINE_ASAN_LOAD_STORE(size)                                    \
 720         void __asan_load##size(unsigned long addr)                      \
 721         {                                                               \
 722                 check_memory_region_inline(addr, size, false, _RET_IP_);\
 723         }                                                               \
 724         EXPORT_SYMBOL(__asan_load##size);                               \
 725         __alias(__asan_load##size)                                      \
 726         void __asan_load##size##_noabort(unsigned long);                \
 727         EXPORT_SYMBOL(__asan_load##size##_noabort);                     \
 728         void __asan_store##size(unsigned long addr)                     \
 729         {                                                               \
 730                 check_memory_region_inline(addr, size, true, _RET_IP_); \
 731         }                                                               \
 732         EXPORT_SYMBOL(__asan_store##size);                              \
 733         __alias(__asan_store##size)                                     \
 734         void __asan_store##size##_noabort(unsigned long);               \
 735         EXPORT_SYMBOL(__asan_store##size##_noabort)
 736
 737 DEFINE_ASAN_LOAD_STORE(1);
 738 DEFINE_ASAN_LOAD_STORE(2);
 739 DEFINE_ASAN_LOAD_STORE(4);
 740 DEFINE_ASAN_LOAD_STORE(8);
 741 DEFINE_ASAN_LOAD_STORE(16);
 742
 743 void __asan_loadN(unsigned long addr, size_t size)
 744 {
 745         check_memory_region(addr, size, false, _RET_IP_);
 746 }
 747 EXPORT_SYMBOL(__asan_loadN);
 748
 749 __alias(__asan_loadN)
 750 void __asan_loadN_noabort(unsigned long, size_t);
 751 EXPORT_SYMBOL(__asan_loadN_noabort);
 752
 753 void __asan_storeN(unsigned long addr, size_t size)
 754 {
 755         check_memory_region(addr, size, true, _RET_IP_);
 756 }
 757 EXPORT_SYMBOL(__asan_storeN);
 758
 759 __alias(__asan_storeN)
 760 void __asan_storeN_noabort(unsigned long, size_t);
 761 EXPORT_SYMBOL(__asan_storeN_noabort);
 762
 763 /* to shut up compiler complaints */
 764 void __asan_handle_no_return(void) {}
 765 EXPORT_SYMBOL(__asan_handle_no_return);
 766
 767 #ifdef CONFIG_MEMORY_HOTPLUG
 768 static int kasan_mem_notifier(struct notifier_block *nb,
 769                         unsigned long action, void *data)
 770 {
 771         return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
 772 }
 773
 774 static int __init kasan_memhotplug_init(void)
 775 {
 776         pr_info("WARNING: KASAN doesn't support memory hot-add\n");
 777         pr_info("Memory hot-add will be disabled\n");
 778
 779         hotplug_memory_notifier(kasan_mem_notifier, 0);
 780
 781         return 0;
 782 }
 783
 784 module_init(kasan_memhotplug_init);
 785 #endif