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
__kasan_check_read(const volatile void * p,unsigned int size)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
__kasan_check_write(const volatile void * p,unsigned int size)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
memset(void * addr,int c,size_t len)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
memmove(void * dest,const void * src,size_t len)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
memcpy(void * dest,const void * src,size_t len)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
__asan_memset(void * addr,int c,ssize_t len)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
__asan_memmove(void * dest,const void * src,ssize_t len)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
__asan_memcpy(void * dest,const void * src,ssize_t len)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
kasan_poison(const void * addr,size_t size,u8 value,bool init)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
kasan_poison_last_granule(const void * addr,size_t size)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
kasan_unpoison(const void * addr,size_t size,bool init)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
shadow_mapped(unsigned long addr)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
kasan_mem_notifier(struct notifier_block * nb,unsigned long action,void * data)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
kasan_memhotplug_init(void)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
kasan_populate_early_vm_area_shadow(void * start,unsigned long size)290 void __init __weak kasan_populate_early_vm_area_shadow(void *start,
291 unsigned long size)
292 {
293 }
294
295 struct vmalloc_populate_data {
296 unsigned long start;
297 struct page **pages;
298 };
299
kasan_populate_vmalloc_pte(pte_t * ptep,unsigned long addr,void * _data)300 static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr,
301 void *_data)
302 {
303 struct vmalloc_populate_data *data = _data;
304 struct page *page;
305 pte_t pte;
306 int index;
307
308 arch_leave_lazy_mmu_mode();
309
310 index = PFN_DOWN(addr - data->start);
311 page = data->pages[index];
312 __memset(page_to_virt(page), KASAN_VMALLOC_INVALID, PAGE_SIZE);
313 pte = pfn_pte(page_to_pfn(page), PAGE_KERNEL);
314
315 spin_lock(&init_mm.page_table_lock);
316 if (likely(pte_none(ptep_get(ptep)))) {
317 set_pte_at(&init_mm, addr, ptep, pte);
318 data->pages[index] = NULL;
319 }
320 spin_unlock(&init_mm.page_table_lock);
321
322 arch_enter_lazy_mmu_mode();
323
324 return 0;
325 }
326
___free_pages_bulk(struct page ** pages,int nr_pages)327 static void ___free_pages_bulk(struct page **pages, int nr_pages)
328 {
329 int i;
330
331 for (i = 0; i < nr_pages; i++) {
332 if (pages[i]) {
333 __free_pages(pages[i], 0);
334 pages[i] = NULL;
335 }
336 }
337 }
338
___alloc_pages_bulk(struct page ** pages,int nr_pages,gfp_t gfp_mask)339 static int ___alloc_pages_bulk(struct page **pages, int nr_pages, gfp_t gfp_mask)
340 {
341 unsigned long nr_populated, nr_total = nr_pages;
342 struct page **page_array = pages;
343
344 while (nr_pages) {
345 nr_populated = alloc_pages_bulk(gfp_mask, nr_pages, pages);
346 if (!nr_populated) {
347 ___free_pages_bulk(page_array, nr_total - nr_pages);
348 return -ENOMEM;
349 }
350 pages += nr_populated;
351 nr_pages -= nr_populated;
352 }
353
354 return 0;
355 }
356
__kasan_populate_vmalloc(unsigned long start,unsigned long end,gfp_t gfp_mask)357 static int __kasan_populate_vmalloc(unsigned long start, unsigned long end, gfp_t gfp_mask)
358 {
359 unsigned long nr_pages, nr_total = PFN_UP(end - start);
360 struct vmalloc_populate_data data;
361 unsigned int flags;
362 int ret = 0;
363
364 data.pages = (struct page **)__get_free_page(gfp_mask | __GFP_ZERO);
365 if (!data.pages)
366 return -ENOMEM;
367
368 while (nr_total) {
369 nr_pages = min(nr_total, PAGE_SIZE / sizeof(data.pages[0]));
370 ret = ___alloc_pages_bulk(data.pages, nr_pages, gfp_mask);
371 if (ret)
372 break;
373
374 data.start = start;
375
376 /*
377 * page tables allocations ignore external gfp mask, enforce it
378 * by the scope API
379 */
380 if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
381 flags = memalloc_nofs_save();
382 else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
383 flags = memalloc_noio_save();
384
385 ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE,
386 kasan_populate_vmalloc_pte, &data);
387
388 if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
389 memalloc_nofs_restore(flags);
390 else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
391 memalloc_noio_restore(flags);
392
393 ___free_pages_bulk(data.pages, nr_pages);
394 if (ret)
395 break;
396
397 start += nr_pages * PAGE_SIZE;
398 nr_total -= nr_pages;
399 }
400
401 free_page((unsigned long)data.pages);
402
403 return ret;
404 }
405
kasan_populate_vmalloc(unsigned long addr,unsigned long size,gfp_t gfp_mask)406 int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask)
407 {
408 unsigned long shadow_start, shadow_end;
409 int ret;
410
411 if (!kasan_arch_is_ready())
412 return 0;
413
414 if (!is_vmalloc_or_module_addr((void *)addr))
415 return 0;
416
417 shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr);
418 shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size);
419
420 /*
421 * User Mode Linux maps enough shadow memory for all of virtual memory
422 * at boot, so doesn't need to allocate more on vmalloc, just clear it.
423 *
424 * The remaining CONFIG_UML checks in this file exist for the same
425 * reason.
426 */
427 if (IS_ENABLED(CONFIG_UML)) {
428 __memset((void *)shadow_start, KASAN_VMALLOC_INVALID, shadow_end - shadow_start);
429 return 0;
430 }
431
432 shadow_start = PAGE_ALIGN_DOWN(shadow_start);
433 shadow_end = PAGE_ALIGN(shadow_end);
434
435 ret = __kasan_populate_vmalloc(shadow_start, shadow_end, gfp_mask);
436 if (ret)
437 return ret;
438
439 flush_cache_vmap(shadow_start, shadow_end);
440
441 /*
442 * We need to be careful about inter-cpu effects here. Consider:
443 *
444 * CPU#0 CPU#1
445 * WRITE_ONCE(p, vmalloc(100)); while (x = READ_ONCE(p)) ;
446 * p[99] = 1;
447 *
448 * With compiler instrumentation, that ends up looking like this:
449 *
450 * CPU#0 CPU#1
451 * // vmalloc() allocates memory
452 * // let a = area->addr
453 * // we reach kasan_populate_vmalloc
454 * // and call kasan_unpoison:
455 * STORE shadow(a), unpoison_val
456 * ...
457 * STORE shadow(a+99), unpoison_val x = LOAD p
458 * // rest of vmalloc process <data dependency>
459 * STORE p, a LOAD shadow(x+99)
460 *
461 * If there is no barrier between the end of unpoisoning the shadow
462 * and the store of the result to p, the stores could be committed
463 * in a different order by CPU#0, and CPU#1 could erroneously observe
464 * poison in the shadow.
465 *
466 * We need some sort of barrier between the stores.
467 *
468 * In the vmalloc() case, this is provided by a smp_wmb() in
469 * clear_vm_uninitialized_flag(). In the per-cpu allocator and in
470 * get_vm_area() and friends, the caller gets shadow allocated but
471 * doesn't have any pages mapped into the virtual address space that
472 * has been reserved. Mapping those pages in will involve taking and
473 * releasing a page-table lock, which will provide the barrier.
474 */
475
476 return 0;
477 }
478
kasan_depopulate_vmalloc_pte(pte_t * ptep,unsigned long addr,void * unused)479 static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr,
480 void *unused)
481 {
482 pte_t pte;
483 int none;
484
485 arch_leave_lazy_mmu_mode();
486
487 spin_lock(&init_mm.page_table_lock);
488 pte = ptep_get(ptep);
489 none = pte_none(pte);
490 if (likely(!none))
491 pte_clear(&init_mm, addr, ptep);
492 spin_unlock(&init_mm.page_table_lock);
493
494 if (likely(!none))
495 __free_page(pfn_to_page(pte_pfn(pte)));
496
497 arch_enter_lazy_mmu_mode();
498
499 return 0;
500 }
501
502 /*
503 * Release the backing for the vmalloc region [start, end), which
504 * lies within the free region [free_region_start, free_region_end).
505 *
506 * This can be run lazily, long after the region was freed. It runs
507 * under vmap_area_lock, so it's not safe to interact with the vmalloc/vmap
508 * infrastructure.
509 *
510 * How does this work?
511 * -------------------
512 *
513 * We have a region that is page aligned, labeled as A.
514 * That might not map onto the shadow in a way that is page-aligned:
515 *
516 * start end
517 * v v
518 * |????????|????????|AAAAAAAA|AA....AA|AAAAAAAA|????????| < vmalloc
519 * -------- -------- -------- -------- --------
520 * | | | | |
521 * | | | /-------/ |
522 * \-------\|/------/ |/---------------/
523 * ||| ||
524 * |??AAAAAA|AAAAAAAA|AA??????| < shadow
525 * (1) (2) (3)
526 *
527 * First we align the start upwards and the end downwards, so that the
528 * shadow of the region aligns with shadow page boundaries. In the
529 * example, this gives us the shadow page (2). This is the shadow entirely
530 * covered by this allocation.
531 *
532 * Then we have the tricky bits. We want to know if we can free the
533 * partially covered shadow pages - (1) and (3) in the example. For this,
534 * we are given the start and end of the free region that contains this
535 * allocation. Extending our previous example, we could have:
536 *
537 * free_region_start free_region_end
538 * | start end |
539 * v v v v
540 * |FFFFFFFF|FFFFFFFF|AAAAAAAA|AA....AA|AAAAAAAA|FFFFFFFF| < vmalloc
541 * -------- -------- -------- -------- --------
542 * | | | | |
543 * | | | /-------/ |
544 * \-------\|/------/ |/---------------/
545 * ||| ||
546 * |FFAAAAAA|AAAAAAAA|AAF?????| < shadow
547 * (1) (2) (3)
548 *
549 * Once again, we align the start of the free region up, and the end of
550 * the free region down so that the shadow is page aligned. So we can free
551 * page (1) - we know no allocation currently uses anything in that page,
552 * because all of it is in the vmalloc free region. But we cannot free
553 * page (3), because we can't be sure that the rest of it is unused.
554 *
555 * We only consider pages that contain part of the original region for
556 * freeing: we don't try to free other pages from the free region or we'd
557 * end up trying to free huge chunks of virtual address space.
558 *
559 * Concurrency
560 * -----------
561 *
562 * How do we know that we're not freeing a page that is simultaneously
563 * being used for a fresh allocation in kasan_populate_vmalloc(_pte)?
564 *
565 * We _can_ have kasan_release_vmalloc and kasan_populate_vmalloc running
566 * at the same time. While we run under free_vmap_area_lock, the population
567 * code does not.
568 *
569 * free_vmap_area_lock instead operates to ensure that the larger range
570 * [free_region_start, free_region_end) is safe: because __alloc_vmap_area and
571 * the per-cpu region-finding algorithm both run under free_vmap_area_lock,
572 * no space identified as free will become used while we are running. This
573 * means that so long as we are careful with alignment and only free shadow
574 * pages entirely covered by the free region, we will not run in to any
575 * trouble - any simultaneous allocations will be for disjoint regions.
576 */
kasan_release_vmalloc(unsigned long start,unsigned long end,unsigned long free_region_start,unsigned long free_region_end,unsigned long flags)577 void kasan_release_vmalloc(unsigned long start, unsigned long end,
578 unsigned long free_region_start,
579 unsigned long free_region_end,
580 unsigned long flags)
581 {
582 void *shadow_start, *shadow_end;
583 unsigned long region_start, region_end;
584 unsigned long size;
585
586 if (!kasan_arch_is_ready())
587 return;
588
589 region_start = ALIGN(start, KASAN_MEMORY_PER_SHADOW_PAGE);
590 region_end = ALIGN_DOWN(end, KASAN_MEMORY_PER_SHADOW_PAGE);
591
592 free_region_start = ALIGN(free_region_start, KASAN_MEMORY_PER_SHADOW_PAGE);
593
594 if (start != region_start &&
595 free_region_start < region_start)
596 region_start -= KASAN_MEMORY_PER_SHADOW_PAGE;
597
598 free_region_end = ALIGN_DOWN(free_region_end, KASAN_MEMORY_PER_SHADOW_PAGE);
599
600 if (end != region_end &&
601 free_region_end > region_end)
602 region_end += KASAN_MEMORY_PER_SHADOW_PAGE;
603
604 shadow_start = kasan_mem_to_shadow((void *)region_start);
605 shadow_end = kasan_mem_to_shadow((void *)region_end);
606
607 if (shadow_end > shadow_start) {
608 size = shadow_end - shadow_start;
609 if (IS_ENABLED(CONFIG_UML)) {
610 __memset(shadow_start, KASAN_SHADOW_INIT, shadow_end - shadow_start);
611 return;
612 }
613
614
615 if (flags & KASAN_VMALLOC_PAGE_RANGE)
616 apply_to_existing_page_range(&init_mm,
617 (unsigned long)shadow_start,
618 size, kasan_depopulate_vmalloc_pte,
619 NULL);
620
621 if (flags & KASAN_VMALLOC_TLB_FLUSH)
622 flush_tlb_kernel_range((unsigned long)shadow_start,
623 (unsigned long)shadow_end);
624 }
625 }
626
__kasan_unpoison_vmalloc(const void * start,unsigned long size,kasan_vmalloc_flags_t flags)627 void *__kasan_unpoison_vmalloc(const void *start, unsigned long size,
628 kasan_vmalloc_flags_t flags)
629 {
630 /*
631 * Software KASAN modes unpoison both VM_ALLOC and non-VM_ALLOC
632 * mappings, so the KASAN_VMALLOC_VM_ALLOC flag is ignored.
633 * Software KASAN modes can't optimize zeroing memory by combining it
634 * with setting memory tags, so the KASAN_VMALLOC_INIT flag is ignored.
635 */
636
637 if (!kasan_arch_is_ready())
638 return (void *)start;
639
640 if (!is_vmalloc_or_module_addr(start))
641 return (void *)start;
642
643 /*
644 * Don't tag executable memory with the tag-based mode.
645 * The kernel doesn't tolerate having the PC register tagged.
646 */
647 if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) &&
648 !(flags & KASAN_VMALLOC_PROT_NORMAL))
649 return (void *)start;
650
651 start = set_tag(start, kasan_random_tag());
652 kasan_unpoison(start, size, false);
653 return (void *)start;
654 }
655
656 /*
657 * Poison the shadow for a vmalloc region. Called as part of the
658 * freeing process at the time the region is freed.
659 */
__kasan_poison_vmalloc(const void * start,unsigned long size)660 void __kasan_poison_vmalloc(const void *start, unsigned long size)
661 {
662 if (!kasan_arch_is_ready())
663 return;
664
665 if (!is_vmalloc_or_module_addr(start))
666 return;
667
668 size = round_up(size, KASAN_GRANULE_SIZE);
669 kasan_poison(start, size, KASAN_VMALLOC_INVALID, false);
670 }
671
672 #else /* CONFIG_KASAN_VMALLOC */
673
kasan_alloc_module_shadow(void * addr,size_t size,gfp_t gfp_mask)674 int kasan_alloc_module_shadow(void *addr, size_t size, gfp_t gfp_mask)
675 {
676 void *ret;
677 size_t scaled_size;
678 size_t shadow_size;
679 unsigned long shadow_start;
680
681 shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
682 scaled_size = (size + KASAN_GRANULE_SIZE - 1) >>
683 KASAN_SHADOW_SCALE_SHIFT;
684 shadow_size = round_up(scaled_size, PAGE_SIZE);
685
686 if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
687 return -EINVAL;
688
689 if (IS_ENABLED(CONFIG_UML)) {
690 __memset((void *)shadow_start, KASAN_SHADOW_INIT, shadow_size);
691 return 0;
692 }
693
694 ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
695 shadow_start + shadow_size,
696 GFP_KERNEL,
697 PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
698 __builtin_return_address(0));
699
700 if (ret) {
701 struct vm_struct *vm = find_vm_area(addr);
702 __memset(ret, KASAN_SHADOW_INIT, shadow_size);
703 vm->flags |= VM_KASAN;
704 kmemleak_ignore(ret);
705
706 if (vm->flags & VM_DEFER_KMEMLEAK)
707 kmemleak_vmalloc(vm, size, gfp_mask);
708
709 return 0;
710 }
711
712 return -ENOMEM;
713 }
714
kasan_free_module_shadow(const struct vm_struct * vm)715 void kasan_free_module_shadow(const struct vm_struct *vm)
716 {
717 if (IS_ENABLED(CONFIG_UML))
718 return;
719
720 if (vm->flags & VM_KASAN)
721 vfree(kasan_mem_to_shadow(vm->addr));
722 }
723
724 #endif
725