mm/kasan/shadow.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * This file contains KASAN runtime code that manages shadow memory for
   4  * generic and software tag-based KASAN modes.
   5  *
   6  * Copyright (c) 2014 Samsung Electronics Co., Ltd.
   7  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
   8  *
   9  * Some code borrowed from https://github.com/xairy/kasan-prototype by
  10  *        Andrey Konovalov <andreyknvl@gmail.com>
  11  */
  12
  13 #include <linux/init.h>
  14 #include <linux/kasan.h>
  15 #include <linux/kernel.h>
  16 #include <linux/kfence.h>
  17 #include <linux/kmemleak.h>
  18 #include <linux/memory.h>
  19 #include <linux/mm.h>
  20 #include <linux/string.h>
  21 #include <linux/types.h>
  22 #include <linux/vmalloc.h>
  23
  24 #include <asm/cacheflush.h>
  25 #include <asm/tlbflush.h>
  26
  27 #include "kasan.h"
  28
  29 bool __kasan_check_read(const volatile void *p, unsigned int size)
  30 {
  31         return kasan_check_range((void *)p, size, false, _RET_IP_);
  32 }
  33 EXPORT_SYMBOL(__kasan_check_read);
  34
  35 bool __kasan_check_write(const volatile void *p, unsigned int size)
  36 {
  37         return kasan_check_range((void *)p, size, true, _RET_IP_);
  38 }
  39 EXPORT_SYMBOL(__kasan_check_write);
  40
  41 #if !defined(CONFIG_CC_HAS_KASAN_MEMINTRINSIC_PREFIX) && !defined(CONFIG_GENERIC_ENTRY)
  42 /*
  43  * CONFIG_GENERIC_ENTRY relies on compiler emitted mem*() calls to not be
  44  * instrumented. KASAN enabled toolchains should emit __asan_mem*() functions
  45  * for the sites they want to instrument.
  46  *
  47  * If we have a compiler that can instrument meminstrinsics, never override
  48  * these, so that non-instrumented files can safely consider them as builtins.
  49  */
  50 #undef memset
  51 void *memset(void *addr, int c, size_t len)
  52 {
  53         if (!kasan_check_range(addr, len, true, _RET_IP_))
  54                 return NULL;
  55
  56         return __memset(addr, c, len);
  57 }
  58
  59 #ifdef __HAVE_ARCH_MEMMOVE
  60 #undef memmove
  61 void *memmove(void *dest, const void *src, size_t len)
  62 {
  63         if (!kasan_check_range(src, len, false, _RET_IP_) ||
  64             !kasan_check_range(dest, len, true, _RET_IP_))
  65                 return NULL;
  66
  67         return __memmove(dest, src, len);
  68 }
  69 #endif
  70
  71 #undef memcpy
  72 void *memcpy(void *dest, const void *src, size_t len)
  73 {
  74         if (!kasan_check_range(src, len, false, _RET_IP_) ||
  75             !kasan_check_range(dest, len, true, _RET_IP_))
  76                 return NULL;
  77
  78         return __memcpy(dest, src, len);
  79 }
  80 #endif
  81
  82 void *__asan_memset(void *addr, int c, ssize_t len)
  83 {
  84         if (!kasan_check_range(addr, len, true, _RET_IP_))
  85                 return NULL;
  86
  87         return __memset(addr, c, len);
  88 }
  89 EXPORT_SYMBOL(__asan_memset);
  90
  91 #ifdef __HAVE_ARCH_MEMMOVE
  92 void *__asan_memmove(void *dest, const void *src, ssize_t len)
  93 {
  94         if (!kasan_check_range(src, len, false, _RET_IP_) ||
  95             !kasan_check_range(dest, len, true, _RET_IP_))
  96                 return NULL;
  97
  98         return __memmove(dest, src, len);
  99 }
 100 EXPORT_SYMBOL(__asan_memmove);
 101 #endif
 102
 103 void *__asan_memcpy(void *dest, const void *src, ssize_t len)
 104 {
 105         if (!kasan_check_range(src, len, false, _RET_IP_) ||
 106             !kasan_check_range(dest, len, true, _RET_IP_))
 107                 return NULL;
 108
 109         return __memcpy(dest, src, len);
 110 }
 111 EXPORT_SYMBOL(__asan_memcpy);
 112
 113 #ifdef CONFIG_KASAN_SW_TAGS
 114 void *__hwasan_memset(void *addr, int c, ssize_t len) __alias(__asan_memset);
 115 EXPORT_SYMBOL(__hwasan_memset);
 116 #ifdef __HAVE_ARCH_MEMMOVE
 117 void *__hwasan_memmove(void *dest, const void *src, ssize_t len) __alias(__asan_memmove);
 118 EXPORT_SYMBOL(__hwasan_memmove);
 119 #endif
 120 void *__hwasan_memcpy(void *dest, const void *src, ssize_t len) __alias(__asan_memcpy);
 121 EXPORT_SYMBOL(__hwasan_memcpy);
 122 #endif
 123
 124 void kasan_poison(const void *addr, size_t size, u8 value, bool init)
 125 {
 126         void *shadow_start, *shadow_end;
 127
 128         if (!kasan_arch_is_ready())
 129                 return;
 130
 131         /*
 132          * Perform shadow offset calculation based on untagged address, as
 133          * some of the callers (e.g. kasan_poison_new_object) pass tagged
 134          * addresses to this function.
 135          */
 136         addr = kasan_reset_tag(addr);
 137
 138         if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
 139                 return;
 140         if (WARN_ON(size & KASAN_GRANULE_MASK))
 141                 return;
 142
 143         shadow_start = kasan_mem_to_shadow(addr);
 144         shadow_end = kasan_mem_to_shadow(addr + size);
 145
 146         __memset(shadow_start, value, shadow_end - shadow_start);
 147 }
 148 EXPORT_SYMBOL_GPL(kasan_poison);
 149
 150 #ifdef CONFIG_KASAN_GENERIC
 151 void kasan_poison_last_granule(const void *addr, size_t size)
 152 {
 153         if (!kasan_arch_is_ready())
 154                 return;
 155
 156         if (size & KASAN_GRANULE_MASK) {
 157                 u8 *shadow = (u8 *)kasan_mem_to_shadow(addr + size);
 158                 *shadow = size & KASAN_GRANULE_MASK;
 159         }
 160 }
 161 #endif
 162
 163 void kasan_unpoison(const void *addr, size_t size, bool init)
 164 {
 165         u8 tag = get_tag(addr);
 166
 167         /*
 168          * Perform shadow offset calculation based on untagged address, as
 169          * some of the callers (e.g. kasan_unpoison_new_object) pass tagged
 170          * addresses to this function.
 171          */
 172         addr = kasan_reset_tag(addr);
 173
 174         if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
 175                 return;
 176
 177         /* Unpoison all granules that cover the object. */
 178         kasan_poison(addr, round_up(size, KASAN_GRANULE_SIZE), tag, false);
 179
 180         /* Partially poison the last granule for the generic mode. */
 181         if (IS_ENABLED(CONFIG_KASAN_GENERIC))
 182                 kasan_poison_last_granule(addr, size);
 183 }
 184
 185 #ifdef CONFIG_MEMORY_HOTPLUG
 186 static bool shadow_mapped(unsigned long addr)
 187 {
 188         pgd_t *pgd = pgd_offset_k(addr);
 189         p4d_t *p4d;
 190         pud_t *pud;
 191         pmd_t *pmd;
 192         pte_t *pte;
 193
 194         if (pgd_none(*pgd))
 195                 return false;
 196         p4d = p4d_offset(pgd, addr);
 197         if (p4d_none(*p4d))
 198                 return false;
 199         pud = pud_offset(p4d, addr);
 200         if (pud_none(*pud))
 201                 return false;
 202         if (pud_leaf(*pud))
 203                 return true;
 204         pmd = pmd_offset(pud, addr);
 205         if (pmd_none(*pmd))
 206                 return false;
 207         if (pmd_leaf(*pmd))
 208                 return true;
 209         pte = pte_offset_kernel(pmd, addr);
 210         return !pte_none(ptep_get(pte));
 211 }
 212
 213 static int __meminit kasan_mem_notifier(struct notifier_block *nb,
 214                         unsigned long action, void *data)
 215 {
 216         struct memory_notify *mem_data = data;
 217         unsigned long nr_shadow_pages, start_kaddr, shadow_start;
 218         unsigned long shadow_end, shadow_size;
 219
 220         nr_shadow_pages = mem_data->nr_pages >> KASAN_SHADOW_SCALE_SHIFT;
 221         start_kaddr = (unsigned long)pfn_to_kaddr(mem_data->start_pfn);
 222         shadow_start = (unsigned long)kasan_mem_to_shadow((void *)start_kaddr);
 223         shadow_size = nr_shadow_pages << PAGE_SHIFT;
 224         shadow_end = shadow_start + shadow_size;
 225
 226         if (WARN_ON(mem_data->nr_pages % KASAN_GRANULE_SIZE) ||
 227                 WARN_ON(start_kaddr % KASAN_MEMORY_PER_SHADOW_PAGE))
 228                 return NOTIFY_BAD;
 229
 230         switch (action) {
 231         case MEM_GOING_ONLINE: {
 232                 void *ret;
 233
 234                 /*
 235                  * If shadow is mapped already than it must have been mapped
 236                  * during the boot. This could happen if we onlining previously
 237                  * offlined memory.
 238                  */
 239                 if (shadow_mapped(shadow_start))
 240                         return NOTIFY_OK;
 241
 242                 ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start,
 243                                         shadow_end, GFP_KERNEL,
 244                                         PAGE_KERNEL, VM_NO_GUARD,
 245                                         pfn_to_nid(mem_data->start_pfn),
 246                                         __builtin_return_address(0));
 247                 if (!ret)
 248                         return NOTIFY_BAD;
 249
 250                 kmemleak_ignore(ret);
 251                 return NOTIFY_OK;
 252         }
 253         case MEM_CANCEL_ONLINE:
 254         case MEM_OFFLINE: {
 255                 struct vm_struct *vm;
 256
 257                 /*
 258                  * shadow_start was either mapped during boot by kasan_init()
 259                  * or during memory online by __vmalloc_node_range().
 260                  * In the latter case we can use vfree() to free shadow.
 261                  * Non-NULL result of the find_vm_area() will tell us if
 262                  * that was the second case.
 263                  *
 264                  * Currently it's not possible to free shadow mapped
 265                  * during boot by kasan_init(). It's because the code
 266                  * to do that hasn't been written yet. So we'll just
 267                  * leak the memory.
 268                  */
 269                 vm = find_vm_area((void *)shadow_start);
 270                 if (vm)
 271                         vfree((void *)shadow_start);
 272         }
 273         }
 274
 275         return NOTIFY_OK;
 276 }
 277
 278 static int __init kasan_memhotplug_init(void)
 279 {
 280         hotplug_memory_notifier(kasan_mem_notifier, DEFAULT_CALLBACK_PRI);
 281
 282         return 0;
 283 }
 284
 285 core_initcall(kasan_memhotplug_init);
 286 #endif
 287
 288 #ifdef CONFIG_KASAN_VMALLOC
 289
 290 void __init __weak kasan_populate_early_vm_area_shadow(void *start,
 291                                                        unsigned long size)
 292 {
 293 }
 294
 295 static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr,
 296                                       void *unused)
 297 {
 298         unsigned long page;
 299         pte_t pte;
 300
 301         if (likely(!pte_none(ptep_get(ptep))))
 302                 return 0;
 303
 304         page = __get_free_page(GFP_KERNEL);
 305         if (!page)
 306                 return -ENOMEM;
 307
 308         __memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE);
 309         pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL);
 310
 311         spin_lock(&init_mm.page_table_lock);
 312         if (likely(pte_none(ptep_get(ptep)))) {
 313                 set_pte_at(&init_mm, addr, ptep, pte);
 314                 page = 0;
 315         }
 316         spin_unlock(&init_mm.page_table_lock);
 317         if (page)
 318                 free_page(page);
 319         return 0;
 320 }
 321
 322 int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
 323 {
 324         unsigned long shadow_start, shadow_end;
 325         int ret;
 326
 327         if (!kasan_arch_is_ready())
 328                 return 0;
 329
 330         if (!is_vmalloc_or_module_addr((void *)addr))
 331                 return 0;
 332
 333         shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr);
 334         shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size);
 335
 336         /*
 337          * User Mode Linux maps enough shadow memory for all of virtual memory
 338          * at boot, so doesn't need to allocate more on vmalloc, just clear it.
 339          *
 340          * The remaining CONFIG_UML checks in this file exist for the same
 341          * reason.
 342          */
 343         if (IS_ENABLED(CONFIG_UML)) {
 344                 __memset((void *)shadow_start, KASAN_VMALLOC_INVALID, shadow_end - shadow_start);
 345                 return 0;
 346         }
 347
 348         shadow_start = PAGE_ALIGN_DOWN(shadow_start);
 349         shadow_end = PAGE_ALIGN(shadow_end);
 350
 351         ret = apply_to_page_range(&init_mm, shadow_start,
 352                                   shadow_end - shadow_start,
 353                                   kasan_populate_vmalloc_pte, NULL);
 354         if (ret)
 355                 return ret;
 356
 357         flush_cache_vmap(shadow_start, shadow_end);
 358
 359         /*
 360          * We need to be careful about inter-cpu effects here. Consider:
 361          *
 362          *   CPU#0                                CPU#1
 363          * WRITE_ONCE(p, vmalloc(100));         while (x = READ_ONCE(p)) ;
 364          *                                      p[99] = 1;
 365          *
 366          * With compiler instrumentation, that ends up looking like this:
 367          *
 368          *   CPU#0                                CPU#1
 369          * // vmalloc() allocates memory
 370          * // let a = area->addr
 371          * // we reach kasan_populate_vmalloc
 372          * // and call kasan_unpoison:
 373          * STORE shadow(a), unpoison_val
 374          * ...
 375          * STORE shadow(a+99), unpoison_val     x = LOAD p
 376          * // rest of vmalloc process           <data dependency>
 377          * STORE p, a                           LOAD shadow(x+99)
 378          *
 379          * If there is no barrier between the end of unpoisoning the shadow
 380          * and the store of the result to p, the stores could be committed
 381          * in a different order by CPU#0, and CPU#1 could erroneously observe
 382          * poison in the shadow.
 383          *
 384          * We need some sort of barrier between the stores.
 385          *
 386          * In the vmalloc() case, this is provided by a smp_wmb() in
 387          * clear_vm_uninitialized_flag(). In the per-cpu allocator and in
 388          * get_vm_area() and friends, the caller gets shadow allocated but
 389          * doesn't have any pages mapped into the virtual address space that
 390          * has been reserved. Mapping those pages in will involve taking and
 391          * releasing a page-table lock, which will provide the barrier.
 392          */
 393
 394         return 0;
 395 }
 396
 397 static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr,
 398                                         void *unused)
 399 {
 400         unsigned long page;
 401
 402         page = (unsigned long)__va(pte_pfn(ptep_get(ptep)) << PAGE_SHIFT);
 403
 404         spin_lock(&init_mm.page_table_lock);
 405
 406         if (likely(!pte_none(ptep_get(ptep)))) {
 407                 pte_clear(&init_mm, addr, ptep);
 408                 free_page(page);
 409         }
 410         spin_unlock(&init_mm.page_table_lock);
 411
 412         return 0;
 413 }
 414
 415 /*
 416  * Release the backing for the vmalloc region [start, end), which
 417  * lies within the free region [free_region_start, free_region_end).
 418  *
 419  * This can be run lazily, long after the region was freed. It runs
 420  * under vmap_area_lock, so it's not safe to interact with the vmalloc/vmap
 421  * infrastructure.
 422  *
 423  * How does this work?
 424  * -------------------
 425  *
 426  * We have a region that is page aligned, labeled as A.
 427  * That might not map onto the shadow in a way that is page-aligned:
 428  *
 429  *                    start                     end
 430  *                    v                         v
 431  * |????????|????????|AAAAAAAA|AA....AA|AAAAAAAA|????????| < vmalloc
 432  *  -------- -------- --------          -------- --------
 433  *      |        |       |                 |        |
 434  *      |        |       |         /-------/        |
 435  *      \-------\|/------/         |/---------------/
 436  *              |||                ||
 437  *             |??AAAAAA|AAAAAAAA|AA??????|                < shadow
 438  *                 (1)      (2)      (3)
 439  *
 440  * First we align the start upwards and the end downwards, so that the
 441  * shadow of the region aligns with shadow page boundaries. In the
 442  * example, this gives us the shadow page (2). This is the shadow entirely
 443  * covered by this allocation.
 444  *
 445  * Then we have the tricky bits. We want to know if we can free the
 446  * partially covered shadow pages - (1) and (3) in the example. For this,
 447  * we are given the start and end of the free region that contains this
 448  * allocation. Extending our previous example, we could have:
 449  *
 450  *  free_region_start                                    free_region_end
 451  *  |                 start                     end      |
 452  *  v                 v                         v        v
 453  * |FFFFFFFF|FFFFFFFF|AAAAAAAA|AA....AA|AAAAAAAA|FFFFFFFF| < vmalloc
 454  *  -------- -------- --------          -------- --------
 455  *      |        |       |                 |        |
 456  *      |        |       |         /-------/        |
 457  *      \-------\|/------/         |/---------------/
 458  *              |||                ||
 459  *             |FFAAAAAA|AAAAAAAA|AAF?????|                < shadow
 460  *                 (1)      (2)      (3)
 461  *
 462  * Once again, we align the start of the free region up, and the end of
 463  * the free region down so that the shadow is page aligned. So we can free
 464  * page (1) - we know no allocation currently uses anything in that page,
 465  * because all of it is in the vmalloc free region. But we cannot free
 466  * page (3), because we can't be sure that the rest of it is unused.
 467  *
 468  * We only consider pages that contain part of the original region for
 469  * freeing: we don't try to free other pages from the free region or we'd
 470  * end up trying to free huge chunks of virtual address space.
 471  *
 472  * Concurrency
 473  * -----------
 474  *
 475  * How do we know that we're not freeing a page that is simultaneously
 476  * being used for a fresh allocation in kasan_populate_vmalloc(_pte)?
 477  *
 478  * We _can_ have kasan_release_vmalloc and kasan_populate_vmalloc running
 479  * at the same time. While we run under free_vmap_area_lock, the population
 480  * code does not.
 481  *
 482  * free_vmap_area_lock instead operates to ensure that the larger range
 483  * [free_region_start, free_region_end) is safe: because __alloc_vmap_area and
 484  * the per-cpu region-finding algorithm both run under free_vmap_area_lock,
 485  * no space identified as free will become used while we are running. This
 486  * means that so long as we are careful with alignment and only free shadow
 487  * pages entirely covered by the free region, we will not run in to any
 488  * trouble - any simultaneous allocations will be for disjoint regions.
 489  */
 490 void kasan_release_vmalloc(unsigned long start, unsigned long end,
 491                            unsigned long free_region_start,
 492                            unsigned long free_region_end,
 493                            unsigned long flags)
 494 {
 495         void *shadow_start, *shadow_end;
 496         unsigned long region_start, region_end;
 497         unsigned long size;
 498
 499         if (!kasan_arch_is_ready())
 500                 return;
 501
 502         region_start = ALIGN(start, KASAN_MEMORY_PER_SHADOW_PAGE);
 503         region_end = ALIGN_DOWN(end, KASAN_MEMORY_PER_SHADOW_PAGE);
 504
 505         free_region_start = ALIGN(free_region_start, KASAN_MEMORY_PER_SHADOW_PAGE);
 506
 507         if (start != region_start &&
 508             free_region_start < region_start)
 509                 region_start -= KASAN_MEMORY_PER_SHADOW_PAGE;
 510
 511         free_region_end = ALIGN_DOWN(free_region_end, KASAN_MEMORY_PER_SHADOW_PAGE);
 512
 513         if (end != region_end &&
 514             free_region_end > region_end)
 515                 region_end += KASAN_MEMORY_PER_SHADOW_PAGE;
 516
 517         shadow_start = kasan_mem_to_shadow((void *)region_start);
 518         shadow_end = kasan_mem_to_shadow((void *)region_end);
 519
 520         if (shadow_end > shadow_start) {
 521                 size = shadow_end - shadow_start;
 522                 if (IS_ENABLED(CONFIG_UML)) {
 523                         __memset(shadow_start, KASAN_SHADOW_INIT, shadow_end - shadow_start);
 524                         return;
 525                 }
 526
 527
 528                 if (flags & KASAN_VMALLOC_PAGE_RANGE)
 529                         apply_to_existing_page_range(&init_mm,
 530                                              (unsigned long)shadow_start,
 531                                              size, kasan_depopulate_vmalloc_pte,
 532                                              NULL);
 533
 534                 if (flags & KASAN_VMALLOC_TLB_FLUSH)
 535                         flush_tlb_kernel_range((unsigned long)shadow_start,
 536                                                (unsigned long)shadow_end);
 537         }
 538 }
 539
 540 void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
 541                                kasan_vmalloc_flags_t flags)
 542 {
 543         /*
 544          * Software KASAN modes unpoison both VM_ALLOC and non-VM_ALLOC
 545          * mappings, so the KASAN_VMALLOC_VM_ALLOC flag is ignored.
 546          * Software KASAN modes can't optimize zeroing memory by combining it
 547          * with setting memory tags, so the KASAN_VMALLOC_INIT flag is ignored.
 548          */
 549
 550         if (!kasan_arch_is_ready())
 551                 return (void *)start;
 552
 553         if (!is_vmalloc_or_module_addr(start))
 554                 return (void *)start;
 555
 556         /*
 557          * Don't tag executable memory with the tag-based mode.
 558          * The kernel doesn't tolerate having the PC register tagged.
 559          */
 560         if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) &&
 561             !(flags & KASAN_VMALLOC_PROT_NORMAL))
 562                 return (void *)start;
 563
 564         start = set_tag(start, kasan_random_tag());
 565         kasan_unpoison(start, size, false);
 566         return (void *)start;
 567 }
 568
 569 /*
 570  * Poison the shadow for a vmalloc region. Called as part of the
 571  * freeing process at the time the region is freed.
 572  */
 573 void __kasan_poison_vmalloc(const void *start, unsigned long size)
 574 {
 575         if (!kasan_arch_is_ready())
 576                 return;
 577
 578         if (!is_vmalloc_or_module_addr(start))
 579                 return;
 580
 581         size = round_up(size, KASAN_GRANULE_SIZE);
 582         kasan_poison(start, size, KASAN_VMALLOC_INVALID, false);
 583 }
 584
 585 #else /* CONFIG_KASAN_VMALLOC */
 586
 587 int kasan_alloc_module_shadow(void *addr, size_t size, gfp_t gfp_mask)
 588 {
 589         void *ret;
 590         size_t scaled_size;
 591         size_t shadow_size;
 592         unsigned long shadow_start;
 593
 594         shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
 595         scaled_size = (size + KASAN_GRANULE_SIZE - 1) >>
 596                                 KASAN_SHADOW_SCALE_SHIFT;
 597         shadow_size = round_up(scaled_size, PAGE_SIZE);
 598
 599         if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
 600                 return -EINVAL;
 601
 602         if (IS_ENABLED(CONFIG_UML)) {
 603                 __memset((void *)shadow_start, KASAN_SHADOW_INIT, shadow_size);
 604                 return 0;
 605         }
 606
 607         ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
 608                         shadow_start + shadow_size,
 609                         GFP_KERNEL,
 610                         PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
 611                         __builtin_return_address(0));
 612
 613         if (ret) {
 614                 struct vm_struct *vm = find_vm_area(addr);
 615                 __memset(ret, KASAN_SHADOW_INIT, shadow_size);
 616                 vm->flags |= VM_KASAN;
 617                 kmemleak_ignore(ret);
 618
 619                 if (vm->flags & VM_DEFER_KMEMLEAK)
 620                         kmemleak_vmalloc(vm, size, gfp_mask);
 621
 622                 return 0;
 623         }
 624
 625         return -ENOMEM;
 626 }
 627
 628 void kasan_free_module_shadow(const struct vm_struct *vm)
 629 {
 630         if (IS_ENABLED(CONFIG_UML))
 631                 return;
 632
 633         if (vm->flags & VM_KASAN)
 634                 vfree(kasan_mem_to_shadow(vm->addr));
 635 }
 636
 637 #endif