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 void kasan_enable_current(void)
  43 {
  44         current->kasan_depth++;
  45 }
  46
  47 void kasan_disable_current(void)
  48 {
  49         current->kasan_depth--;
  50 }
  51
  52 /*
  53  * Poisons the shadow memory for 'size' bytes starting from 'addr'.
  54  * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
  55  */
  56 static void kasan_poison_shadow(const void *address, size_t size, u8 value)
  57 {
  58         void *shadow_start, *shadow_end;
  59
  60         shadow_start = kasan_mem_to_shadow(address);
  61         shadow_end = kasan_mem_to_shadow(address + size);
  62
  63         memset(shadow_start, value, shadow_end - shadow_start);
  64 }
  65
  66 void kasan_unpoison_shadow(const void *address, size_t size)
  67 {
  68         kasan_poison_shadow(address, size, 0);
  69
  70         if (size & KASAN_SHADOW_MASK) {
  71                 u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
  72                 *shadow = size & KASAN_SHADOW_MASK;
  73         }
  74 }
  75
  76 static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
  77 {
  78         void *base = task_stack_page(task);
  79         size_t size = sp - base;
  80
  81         kasan_unpoison_shadow(base, size);
  82 }
  83
  84 /* Unpoison the entire stack for a task. */
  85 void kasan_unpoison_task_stack(struct task_struct *task)
  86 {
  87         __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE);
  88 }
  89
  90 /* Unpoison the stack for the current task beyond a watermark sp value. */
  91 asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
  92 {
  93         /*
  94          * Calculate the task stack base address.  Avoid using 'current'
  95          * because this function is called by early resume code which hasn't
  96          * yet set up the percpu register (%gs).
  97          */
  98         void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
  99
 100         kasan_unpoison_shadow(base, watermark - base);
 101 }
 102
 103 /*
 104  * Clear all poison for the region between the current SP and a provided
 105  * watermark value, as is sometimes required prior to hand-crafted asm function
 106  * returns in the middle of functions.
 107  */
 108 void kasan_unpoison_stack_above_sp_to(const void *watermark)
 109 {
 110         const void *sp = __builtin_frame_address(0);
 111         size_t size = watermark - sp;
 112
 113         if (WARN_ON(sp > watermark))
 114                 return;
 115         kasan_unpoison_shadow(sp, size);
 116 }
 117
 118 /*
 119  * All functions below always inlined so compiler could
 120  * perform better optimizations in each of __asan_loadX/__assn_storeX
 121  * depending on memory access size X.
 122  */
 123
 124 static __always_inline bool memory_is_poisoned_1(unsigned long addr)
 125 {
 126         s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
 127
 128         if (unlikely(shadow_value)) {
 129                 s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
 130                 return unlikely(last_accessible_byte >= shadow_value);
 131         }
 132
 133         return false;
 134 }
 135
 136 static __always_inline bool memory_is_poisoned_2(unsigned long addr)
 137 {
 138         u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
 139
 140         if (unlikely(*shadow_addr)) {
 141                 if (memory_is_poisoned_1(addr + 1))
 142                         return true;
 143
 144                 /*
 145                  * If single shadow byte covers 2-byte access, we don't
 146                  * need to do anything more. Otherwise, test the first
 147                  * shadow byte.
 148                  */
 149                 if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0))
 150                         return false;
 151
 152                 return unlikely(*(u8 *)shadow_addr);
 153         }
 154
 155         return false;
 156 }
 157
 158 static __always_inline bool memory_is_poisoned_4(unsigned long addr)
 159 {
 160         u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
 161
 162         if (unlikely(*shadow_addr)) {
 163                 if (memory_is_poisoned_1(addr + 3))
 164                         return true;
 165
 166                 /*
 167                  * If single shadow byte covers 4-byte access, we don't
 168                  * need to do anything more. Otherwise, test the first
 169                  * shadow byte.
 170                  */
 171                 if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3))
 172                         return false;
 173
 174                 return unlikely(*(u8 *)shadow_addr);
 175         }
 176
 177         return false;
 178 }
 179
 180 static __always_inline bool memory_is_poisoned_8(unsigned long addr)
 181 {
 182         u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
 183
 184         if (unlikely(*shadow_addr)) {
 185                 if (memory_is_poisoned_1(addr + 7))
 186                         return true;
 187
 188                 /*
 189                  * If single shadow byte covers 8-byte access, we don't
 190                  * need to do anything more. Otherwise, test the first
 191                  * shadow byte.
 192                  */
 193                 if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
 194                         return false;
 195
 196                 return unlikely(*(u8 *)shadow_addr);
 197         }
 198
 199         return false;
 200 }
 201
 202 static __always_inline bool memory_is_poisoned_16(unsigned long addr)
 203 {
 204         u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr);
 205
 206         if (unlikely(*shadow_addr)) {
 207                 u16 shadow_first_bytes = *(u16 *)shadow_addr;
 208
 209                 if (unlikely(shadow_first_bytes))
 210                         return true;
 211
 212                 /*
 213                  * If two shadow bytes covers 16-byte access, we don't
 214                  * need to do anything more. Otherwise, test the last
 215                  * shadow byte.
 216                  */
 217                 if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
 218                         return false;
 219
 220                 return memory_is_poisoned_1(addr + 15);
 221         }
 222
 223         return false;
 224 }
 225
 226 static __always_inline unsigned long bytes_is_zero(const u8 *start,
 227                                         size_t size)
 228 {
 229         while (size) {
 230                 if (unlikely(*start))
 231                         return (unsigned long)start;
 232                 start++;
 233                 size--;
 234         }
 235
 236         return 0;
 237 }
 238
 239 static __always_inline unsigned long memory_is_zero(const void *start,
 240                                                 const void *end)
 241 {
 242         unsigned int words;
 243         unsigned long ret;
 244         unsigned int prefix = (unsigned long)start % 8;
 245
 246         if (end - start <= 16)
 247                 return bytes_is_zero(start, end - start);
 248
 249         if (prefix) {
 250                 prefix = 8 - prefix;
 251                 ret = bytes_is_zero(start, prefix);
 252                 if (unlikely(ret))
 253                         return ret;
 254                 start += prefix;
 255         }
 256
 257         words = (end - start) / 8;
 258         while (words) {
 259                 if (unlikely(*(u64 *)start))
 260                         return bytes_is_zero(start, 8);
 261                 start += 8;
 262                 words--;
 263         }
 264
 265         return bytes_is_zero(start, (end - start) % 8);
 266 }
 267
 268 static __always_inline bool memory_is_poisoned_n(unsigned long addr,
 269                                                 size_t size)
 270 {
 271         unsigned long ret;
 272
 273         ret = memory_is_zero(kasan_mem_to_shadow((void *)addr),
 274                         kasan_mem_to_shadow((void *)addr + size - 1) + 1);
 275
 276         if (unlikely(ret)) {
 277                 unsigned long last_byte = addr + size - 1;
 278                 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
 279
 280                 if (unlikely(ret != (unsigned long)last_shadow ||
 281                         ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
 282                         return true;
 283         }
 284         return false;
 285 }
 286
 287 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
 288 {
 289         if (__builtin_constant_p(size)) {
 290                 switch (size) {
 291                 case 1:
 292                         return memory_is_poisoned_1(addr);
 293                 case 2:
 294                         return memory_is_poisoned_2(addr);
 295                 case 4:
 296                         return memory_is_poisoned_4(addr);
 297                 case 8:
 298                         return memory_is_poisoned_8(addr);
 299                 case 16:
 300                         return memory_is_poisoned_16(addr);
 301                 default:
 302                         BUILD_BUG();
 303                 }
 304         }
 305
 306         return memory_is_poisoned_n(addr, size);
 307 }
 308
 309 static __always_inline void check_memory_region_inline(unsigned long addr,
 310                                                 size_t size, bool write,
 311                                                 unsigned long ret_ip)
 312 {
 313         if (unlikely(size == 0))
 314                 return;
 315
 316         if (unlikely((void *)addr <
 317                 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
 318                 kasan_report(addr, size, write, ret_ip);
 319                 return;
 320         }
 321
 322         if (likely(!memory_is_poisoned(addr, size)))
 323                 return;
 324
 325         kasan_report(addr, size, write, ret_ip);
 326 }
 327
 328 static void check_memory_region(unsigned long addr,
 329                                 size_t size, bool write,
 330                                 unsigned long ret_ip)
 331 {
 332         check_memory_region_inline(addr, size, write, ret_ip);
 333 }
 334
 335 void kasan_check_read(const void *p, unsigned int size)
 336 {
 337         check_memory_region((unsigned long)p, size, false, _RET_IP_);
 338 }
 339 EXPORT_SYMBOL(kasan_check_read);
 340
 341 void kasan_check_write(const void *p, unsigned int size)
 342 {
 343         check_memory_region((unsigned long)p, size, true, _RET_IP_);
 344 }
 345 EXPORT_SYMBOL(kasan_check_write);
 346
 347 #undef memset
 348 void *memset(void *addr, int c, size_t len)
 349 {
 350         check_memory_region((unsigned long)addr, len, true, _RET_IP_);
 351
 352         return __memset(addr, c, len);
 353 }
 354
 355 #undef memmove
 356 void *memmove(void *dest, const void *src, size_t len)
 357 {
 358         check_memory_region((unsigned long)src, len, false, _RET_IP_);
 359         check_memory_region((unsigned long)dest, len, true, _RET_IP_);
 360
 361         return __memmove(dest, src, len);
 362 }
 363
 364 #undef memcpy
 365 void *memcpy(void *dest, const void *src, size_t len)
 366 {
 367         check_memory_region((unsigned long)src, len, false, _RET_IP_);
 368         check_memory_region((unsigned long)dest, len, true, _RET_IP_);
 369
 370         return __memcpy(dest, src, len);
 371 }
 372
 373 void kasan_alloc_pages(struct page *page, unsigned int order)
 374 {
 375         if (likely(!PageHighMem(page)))
 376                 kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
 377 }
 378
 379 void kasan_free_pages(struct page *page, unsigned int order)
 380 {
 381         if (likely(!PageHighMem(page)))
 382                 kasan_poison_shadow(page_address(page),
 383                                 PAGE_SIZE << order,
 384                                 KASAN_FREE_PAGE);
 385 }
 386
 387 /*
 388  * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
 389  * For larger allocations larger redzones are used.
 390  */
 391 static size_t optimal_redzone(size_t object_size)
 392 {
 393         int rz =
 394                 object_size <= 64        - 16   ? 16 :
 395                 object_size <= 128       - 32   ? 32 :
 396                 object_size <= 512       - 64   ? 64 :
 397                 object_size <= 4096      - 128  ? 128 :
 398                 object_size <= (1 << 14) - 256  ? 256 :
 399                 object_size <= (1 << 15) - 512  ? 512 :
 400                 object_size <= (1 << 16) - 1024 ? 1024 : 2048;
 401         return rz;
 402 }
 403
 404 void kasan_cache_create(struct kmem_cache *cache, size_t *size,
 405                         unsigned long *flags)
 406 {
 407         int redzone_adjust;
 408         int orig_size = *size;
 409
 410         /* Add alloc meta. */
 411         cache->kasan_info.alloc_meta_offset = *size;
 412         *size += sizeof(struct kasan_alloc_meta);
 413
 414         /* Add free meta. */
 415         if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor ||
 416             cache->object_size < sizeof(struct kasan_free_meta)) {
 417                 cache->kasan_info.free_meta_offset = *size;
 418                 *size += sizeof(struct kasan_free_meta);
 419         }
 420         redzone_adjust = optimal_redzone(cache->object_size) -
 421                 (*size - cache->object_size);
 422
 423         if (redzone_adjust > 0)
 424                 *size += redzone_adjust;
 425
 426         *size = min(KMALLOC_MAX_SIZE, max(*size, cache->object_size +
 427                                         optimal_redzone(cache->object_size)));
 428
 429         /*
 430          * If the metadata doesn't fit, don't enable KASAN at all.
 431          */
 432         if (*size <= cache->kasan_info.alloc_meta_offset ||
 433                         *size <= cache->kasan_info.free_meta_offset) {
 434                 cache->kasan_info.alloc_meta_offset = 0;
 435                 cache->kasan_info.free_meta_offset = 0;
 436                 *size = orig_size;
 437                 return;
 438         }
 439
 440         *flags |= SLAB_KASAN;
 441 }
 442
 443 void kasan_cache_shrink(struct kmem_cache *cache)
 444 {
 445         quarantine_remove_cache(cache);
 446 }
 447
 448 void kasan_cache_shutdown(struct kmem_cache *cache)
 449 {
 450         quarantine_remove_cache(cache);
 451 }
 452
 453 size_t kasan_metadata_size(struct kmem_cache *cache)
 454 {
 455         return (cache->kasan_info.alloc_meta_offset ?
 456                 sizeof(struct kasan_alloc_meta) : 0) +
 457                 (cache->kasan_info.free_meta_offset ?
 458                 sizeof(struct kasan_free_meta) : 0);
 459 }
 460
 461 void kasan_poison_slab(struct page *page)
 462 {
 463         kasan_poison_shadow(page_address(page),
 464                         PAGE_SIZE << compound_order(page),
 465                         KASAN_KMALLOC_REDZONE);
 466 }
 467
 468 void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
 469 {
 470         kasan_unpoison_shadow(object, cache->object_size);
 471 }
 472
 473 void kasan_poison_object_data(struct kmem_cache *cache, void *object)
 474 {
 475         kasan_poison_shadow(object,
 476                         round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
 477                         KASAN_KMALLOC_REDZONE);
 478 }
 479
 480 static inline int in_irqentry_text(unsigned long ptr)
 481 {
 482         return (ptr >= (unsigned long)&__irqentry_text_start &&
 483                 ptr < (unsigned long)&__irqentry_text_end) ||
 484                 (ptr >= (unsigned long)&__softirqentry_text_start &&
 485                  ptr < (unsigned long)&__softirqentry_text_end);
 486 }
 487
 488 static inline void filter_irq_stacks(struct stack_trace *trace)
 489 {
 490         int i;
 491
 492         if (!trace->nr_entries)
 493                 return;
 494         for (i = 0; i < trace->nr_entries; i++)
 495                 if (in_irqentry_text(trace->entries[i])) {
 496                         /* Include the irqentry function into the stack. */
 497                         trace->nr_entries = i + 1;
 498                         break;
 499                 }
 500 }
 501
 502 static inline depot_stack_handle_t save_stack(gfp_t flags)
 503 {
 504         unsigned long entries[KASAN_STACK_DEPTH];
 505         struct stack_trace trace = {
 506                 .nr_entries = 0,
 507                 .entries = entries,
 508                 .max_entries = KASAN_STACK_DEPTH,
 509                 .skip = 0
 510         };
 511
 512         save_stack_trace(&trace);
 513         filter_irq_stacks(&trace);
 514         if (trace.nr_entries != 0 &&
 515             trace.entries[trace.nr_entries-1] == ULONG_MAX)
 516                 trace.nr_entries--;
 517
 518         return depot_save_stack(&trace, flags);
 519 }
 520
 521 static inline void set_track(struct kasan_track *track, gfp_t flags)
 522 {
 523         track->pid = current->pid;
 524         track->stack = save_stack(flags);
 525 }
 526
 527 struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
 528                                         const void *object)
 529 {
 530         BUILD_BUG_ON(sizeof(struct kasan_alloc_meta) > 32);
 531         return (void *)object + cache->kasan_info.alloc_meta_offset;
 532 }
 533
 534 struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
 535                                       const void *object)
 536 {
 537         BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
 538         return (void *)object + cache->kasan_info.free_meta_offset;
 539 }
 540
 541 void kasan_init_slab_obj(struct kmem_cache *cache, const void *object)
 542 {
 543         struct kasan_alloc_meta *alloc_info;
 544
 545         if (!(cache->flags & SLAB_KASAN))
 546                 return;
 547
 548         alloc_info = get_alloc_info(cache, object);
 549         __memset(alloc_info, 0, sizeof(*alloc_info));
 550 }
 551
 552 void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags)
 553 {
 554         kasan_kmalloc(cache, object, cache->object_size, flags);
 555 }
 556
 557 static void kasan_poison_slab_free(struct kmem_cache *cache, void *object)
 558 {
 559         unsigned long size = cache->object_size;
 560         unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
 561
 562         /* RCU slabs could be legally used after free within the RCU period */
 563         if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
 564                 return;
 565
 566         kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
 567 }
 568
 569 bool kasan_slab_free(struct kmem_cache *cache, void *object)
 570 {
 571         s8 shadow_byte;
 572
 573         /* RCU slabs could be legally used after free within the RCU period */
 574         if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU))
 575                 return false;
 576
 577         shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
 578         if (shadow_byte < 0 || shadow_byte >= KASAN_SHADOW_SCALE_SIZE) {
 579                 kasan_report_double_free(cache, object,
 580                                 __builtin_return_address(1));
 581                 return true;
 582         }
 583
 584         kasan_poison_slab_free(cache, object);
 585
 586         if (unlikely(!(cache->flags & SLAB_KASAN)))
 587                 return false;
 588
 589         set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT);
 590         quarantine_put(get_free_info(cache, object), cache);
 591         return true;
 592 }
 593
 594 void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size,
 595                    gfp_t flags)
 596 {
 597         unsigned long redzone_start;
 598         unsigned long redzone_end;
 599
 600         if (gfpflags_allow_blocking(flags))
 601                 quarantine_reduce();
 602
 603         if (unlikely(object == NULL))
 604                 return;
 605
 606         redzone_start = round_up((unsigned long)(object + size),
 607                                 KASAN_SHADOW_SCALE_SIZE);
 608         redzone_end = round_up((unsigned long)object + cache->object_size,
 609                                 KASAN_SHADOW_SCALE_SIZE);
 610
 611         kasan_unpoison_shadow(object, size);
 612         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
 613                 KASAN_KMALLOC_REDZONE);
 614
 615         if (cache->flags & SLAB_KASAN)
 616                 set_track(&get_alloc_info(cache, object)->alloc_track, flags);
 617 }
 618 EXPORT_SYMBOL(kasan_kmalloc);
 619
 620 void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
 621 {
 622         struct page *page;
 623         unsigned long redzone_start;
 624         unsigned long redzone_end;
 625
 626         if (gfpflags_allow_blocking(flags))
 627                 quarantine_reduce();
 628
 629         if (unlikely(ptr == NULL))
 630                 return;
 631
 632         page = virt_to_page(ptr);
 633         redzone_start = round_up((unsigned long)(ptr + size),
 634                                 KASAN_SHADOW_SCALE_SIZE);
 635         redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
 636
 637         kasan_unpoison_shadow(ptr, size);
 638         kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
 639                 KASAN_PAGE_REDZONE);
 640 }
 641
 642 void kasan_krealloc(const void *object, size_t size, gfp_t flags)
 643 {
 644         struct page *page;
 645
 646         if (unlikely(object == ZERO_SIZE_PTR))
 647                 return;
 648
 649         page = virt_to_head_page(object);
 650
 651         if (unlikely(!PageSlab(page)))
 652                 kasan_kmalloc_large(object, size, flags);
 653         else
 654                 kasan_kmalloc(page->slab_cache, object, size, flags);
 655 }
 656
 657 void kasan_poison_kfree(void *ptr)
 658 {
 659         struct page *page;
 660
 661         page = virt_to_head_page(ptr);
 662
 663         if (unlikely(!PageSlab(page)))
 664                 kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
 665                                 KASAN_FREE_PAGE);
 666         else
 667                 kasan_poison_slab_free(page->slab_cache, ptr);
 668 }
 669
 670 void kasan_kfree_large(const void *ptr)
 671 {
 672         struct page *page = virt_to_page(ptr);
 673
 674         kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
 675                         KASAN_FREE_PAGE);
 676 }
 677
 678 int kasan_module_alloc(void *addr, size_t size)
 679 {
 680         void *ret;
 681         size_t scaled_size;
 682         size_t shadow_size;
 683         unsigned long shadow_start;
 684
 685         shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
 686         scaled_size = (size + KASAN_SHADOW_MASK) >> KASAN_SHADOW_SCALE_SHIFT;
 687         shadow_size = round_up(scaled_size, PAGE_SIZE);
 688
 689         if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
 690                 return -EINVAL;
 691
 692         ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
 693                         shadow_start + shadow_size,
 694                         GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 695                         PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
 696                         __builtin_return_address(0));
 697
 698         if (ret) {
 699                 find_vm_area(addr)->flags |= VM_KASAN;
 700                 kmemleak_ignore(ret);
 701                 return 0;
 702         }
 703
 704         return -ENOMEM;
 705 }
 706
 707 void kasan_free_shadow(const struct vm_struct *vm)
 708 {
 709         if (vm->flags & VM_KASAN)
 710                 vfree(kasan_mem_to_shadow(vm->addr));
 711 }
 712
 713 static void register_global(struct kasan_global *global)
 714 {
 715         size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
 716
 717         kasan_unpoison_shadow(global->beg, global->size);
 718
 719         kasan_poison_shadow(global->beg + aligned_size,
 720                 global->size_with_redzone - aligned_size,
 721                 KASAN_GLOBAL_REDZONE);
 722 }
 723
 724 void __asan_register_globals(struct kasan_global *globals, size_t size)
 725 {
 726         int i;
 727
 728         for (i = 0; i < size; i++)
 729                 register_global(&globals[i]);
 730 }
 731 EXPORT_SYMBOL(__asan_register_globals);
 732
 733 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
 734 {
 735 }
 736 EXPORT_SYMBOL(__asan_unregister_globals);
 737
 738 #define DEFINE_ASAN_LOAD_STORE(size)                                    \
 739         void __asan_load##size(unsigned long addr)                      \
 740         {                                                               \
 741                 check_memory_region_inline(addr, size, false, _RET_IP_);\
 742         }                                                               \
 743         EXPORT_SYMBOL(__asan_load##size);                               \
 744         __alias(__asan_load##size)                                      \
 745         void __asan_load##size##_noabort(unsigned long);                \
 746         EXPORT_SYMBOL(__asan_load##size##_noabort);                     \
 747         void __asan_store##size(unsigned long addr)                     \
 748         {                                                               \
 749                 check_memory_region_inline(addr, size, true, _RET_IP_); \
 750         }                                                               \
 751         EXPORT_SYMBOL(__asan_store##size);                              \
 752         __alias(__asan_store##size)                                     \
 753         void __asan_store##size##_noabort(unsigned long);               \
 754         EXPORT_SYMBOL(__asan_store##size##_noabort)
 755
 756 DEFINE_ASAN_LOAD_STORE(1);
 757 DEFINE_ASAN_LOAD_STORE(2);
 758 DEFINE_ASAN_LOAD_STORE(4);
 759 DEFINE_ASAN_LOAD_STORE(8);
 760 DEFINE_ASAN_LOAD_STORE(16);
 761
 762 void __asan_loadN(unsigned long addr, size_t size)
 763 {
 764         check_memory_region(addr, size, false, _RET_IP_);
 765 }
 766 EXPORT_SYMBOL(__asan_loadN);
 767
 768 __alias(__asan_loadN)
 769 void __asan_loadN_noabort(unsigned long, size_t);
 770 EXPORT_SYMBOL(__asan_loadN_noabort);
 771
 772 void __asan_storeN(unsigned long addr, size_t size)
 773 {
 774         check_memory_region(addr, size, true, _RET_IP_);
 775 }
 776 EXPORT_SYMBOL(__asan_storeN);
 777
 778 __alias(__asan_storeN)
 779 void __asan_storeN_noabort(unsigned long, size_t);
 780 EXPORT_SYMBOL(__asan_storeN_noabort);
 781
 782 /* to shut up compiler complaints */
 783 void __asan_handle_no_return(void) {}
 784 EXPORT_SYMBOL(__asan_handle_no_return);
 785
 786 /* Emitted by compiler to poison large objects when they go out of scope. */
 787 void __asan_poison_stack_memory(const void *addr, size_t size)
 788 {
 789         /*
 790          * Addr is KASAN_SHADOW_SCALE_SIZE-aligned and the object is surrounded
 791          * by redzones, so we simply round up size to simplify logic.
 792          */
 793         kasan_poison_shadow(addr, round_up(size, KASAN_SHADOW_SCALE_SIZE),
 794                             KASAN_USE_AFTER_SCOPE);
 795 }
 796 EXPORT_SYMBOL(__asan_poison_stack_memory);
 797
 798 /* Emitted by compiler to unpoison large objects when they go into scope. */
 799 void __asan_unpoison_stack_memory(const void *addr, size_t size)
 800 {
 801         kasan_unpoison_shadow(addr, size);
 802 }
 803 EXPORT_SYMBOL(__asan_unpoison_stack_memory);
 804
 805 #ifdef CONFIG_MEMORY_HOTPLUG
 806 static int kasan_mem_notifier(struct notifier_block *nb,
 807                         unsigned long action, void *data)
 808 {
 809         return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK;
 810 }
 811
 812 static int __init kasan_memhotplug_init(void)
 813 {
 814         pr_info("WARNING: KASAN doesn't support memory hot-add\n");
 815         pr_info("Memory hot-add will be disabled\n");
 816
 817         hotplug_memory_notifier(kasan_mem_notifier, 0);
 818
 819         return 0;
 820 }
 821
 822 core_initcall(kasan_memhotplug_init);
 823 #endif