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 <andreyknvl@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