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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This file contains common KASAN code.
4 *
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 *
8 * Some code borrowed from https://github.com/xairy/kasan-prototype by
9 * Andrey Konovalov <andreyknvl@gmail.com>
10 */
11
12#include <linux/export.h>
13#include <linux/init.h>
14#include <linux/kasan.h>
15#include <linux/kernel.h>
16#include <linux/linkage.h>
17#include <linux/memblock.h>
18#include <linux/memory.h>
19#include <linux/mm.h>
20#include <linux/module.h>
21#include <linux/printk.h>
22#include <linux/sched.h>
23#include <linux/sched/task_stack.h>
24#include <linux/slab.h>
25#include <linux/stacktrace.h>
26#include <linux/string.h>
27#include <linux/types.h>
28#include <linux/bug.h>
29
30#include "kasan.h"
31#include "../slab.h"
32
33struct slab *kasan_addr_to_slab(const void *addr)
34{
35 if (virt_addr_valid(addr))
36 return virt_to_slab(addr);
37 return NULL;
38}
39
40depot_stack_handle_t kasan_save_stack(gfp_t flags, bool can_alloc)
41{
42 unsigned long entries[KASAN_STACK_DEPTH];
43 unsigned int nr_entries;
44
45 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
46 return __stack_depot_save(entries, nr_entries, 0, flags, can_alloc);
47}
48
49void kasan_set_track(struct kasan_track *track, gfp_t flags)
50{
51 track->pid = current->pid;
52 track->stack = kasan_save_stack(flags, true);
53}
54
55#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
56void kasan_enable_current(void)
57{
58 current->kasan_depth++;
59}
60EXPORT_SYMBOL(kasan_enable_current);
61
62void kasan_disable_current(void)
63{
64 current->kasan_depth--;
65}
66EXPORT_SYMBOL(kasan_disable_current);
67
68#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
69
70void __kasan_unpoison_range(const void *address, size_t size)
71{
72 kasan_unpoison(address, size, false);
73}
74
75#ifdef CONFIG_KASAN_STACK
76/* Unpoison the entire stack for a task. */
77void kasan_unpoison_task_stack(struct task_struct *task)
78{
79 void *base = task_stack_page(task);
80
81 kasan_unpoison(base, THREAD_SIZE, false);
82}
83
84/* Unpoison the stack for the current task beyond a watermark sp value. */
85asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
86{
87 /*
88 * Calculate the task stack base address. Avoid using 'current'
89 * because this function is called by early resume code which hasn't
90 * yet set up the percpu register (%gs).
91 */
92 void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
93
94 kasan_unpoison(base, watermark - base, false);
95}
96#endif /* CONFIG_KASAN_STACK */
97
98void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init)
99{
100 u8 tag;
101 unsigned long i;
102
103 if (unlikely(PageHighMem(page)))
104 return;
105
106 tag = kasan_random_tag();
107 kasan_unpoison(set_tag(page_address(page), tag),
108 PAGE_SIZE << order, init);
109 for (i = 0; i < (1 << order); i++)
110 page_kasan_tag_set(page + i, tag);
111}
112
113void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
114{
115 if (likely(!PageHighMem(page)))
116 kasan_poison(page_address(page), PAGE_SIZE << order,
117 KASAN_PAGE_FREE, init);
118}
119
120void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
121{
122 cache->kasan_info.is_kmalloc = true;
123}
124
125void __kasan_poison_slab(struct slab *slab)
126{
127 struct page *page = slab_page(slab);
128 unsigned long i;
129
130 for (i = 0; i < compound_nr(page); i++)
131 page_kasan_tag_reset(page + i);
132 kasan_poison(page_address(page), page_size(page),
133 KASAN_SLAB_REDZONE, false);
134}
135
136void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
137{
138 kasan_unpoison(object, cache->object_size, false);
139}
140
141void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
142{
143 kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
144 KASAN_SLAB_REDZONE, false);
145}
146
147/*
148 * This function assigns a tag to an object considering the following:
149 * 1. A cache might have a constructor, which might save a pointer to a slab
150 * object somewhere (e.g. in the object itself). We preassign a tag for
151 * each object in caches with constructors during slab creation and reuse
152 * the same tag each time a particular object is allocated.
153 * 2. A cache might be SLAB_TYPESAFE_BY_RCU, which means objects can be
154 * accessed after being freed. We preassign tags for objects in these
155 * caches as well.
156 * 3. For SLAB allocator we can't preassign tags randomly since the freelist
157 * is stored as an array of indexes instead of a linked list. Assign tags
158 * based on objects indexes, so that objects that are next to each other
159 * get different tags.
160 */
161static inline u8 assign_tag(struct kmem_cache *cache,
162 const void *object, bool init)
163{
164 if (IS_ENABLED(CONFIG_KASAN_GENERIC))
165 return 0xff;
166
167 /*
168 * If the cache neither has a constructor nor has SLAB_TYPESAFE_BY_RCU
169 * set, assign a tag when the object is being allocated (init == false).
170 */
171 if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU))
172 return init ? KASAN_TAG_KERNEL : kasan_random_tag();
173
174 /* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU: */
175#ifdef CONFIG_SLAB
176 /* For SLAB assign tags based on the object index in the freelist. */
177 return (u8)obj_to_index(cache, virt_to_slab(object), (void *)object);
178#else
179 /*
180 * For SLUB assign a random tag during slab creation, otherwise reuse
181 * the already assigned tag.
182 */
183 return init ? kasan_random_tag() : get_tag(object);
184#endif
185}
186
187void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
188 const void *object)
189{
190 /* Initialize per-object metadata if it is present. */
191 if (kasan_requires_meta())
192 kasan_init_object_meta(cache, object);
193
194 /* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
195 object = set_tag(object, assign_tag(cache, object, true));
196
197 return (void *)object;
198}
199
200static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
201 unsigned long ip, bool quarantine, bool init)
202{
203 void *tagged_object;
204
205 if (!kasan_arch_is_ready())
206 return false;
207
208 tagged_object = object;
209 object = kasan_reset_tag(object);
210
211 if (is_kfence_address(object))
212 return false;
213
214 if (unlikely(nearest_obj(cache, virt_to_slab(object), object) !=
215 object)) {
216 kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_INVALID_FREE);
217 return true;
218 }
219
220 /* RCU slabs could be legally used after free within the RCU period */
221 if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
222 return false;
223
224 if (!kasan_byte_accessible(tagged_object)) {
225 kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_DOUBLE_FREE);
226 return true;
227 }
228
229 kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
230 KASAN_SLAB_FREE, init);
231
232 if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine))
233 return false;
234
235 if (kasan_stack_collection_enabled())
236 kasan_save_free_info(cache, tagged_object);
237
238 return kasan_quarantine_put(cache, object);
239}
240
241bool __kasan_slab_free(struct kmem_cache *cache, void *object,
242 unsigned long ip, bool init)
243{
244 return ____kasan_slab_free(cache, object, ip, true, init);
245}
246
247static inline bool ____kasan_kfree_large(void *ptr, unsigned long ip)
248{
249 if (!kasan_arch_is_ready())
250 return false;
251
252 if (ptr != page_address(virt_to_head_page(ptr))) {
253 kasan_report_invalid_free(ptr, ip, KASAN_REPORT_INVALID_FREE);
254 return true;
255 }
256
257 if (!kasan_byte_accessible(ptr)) {
258 kasan_report_invalid_free(ptr, ip, KASAN_REPORT_DOUBLE_FREE);
259 return true;
260 }
261
262 /*
263 * The object will be poisoned by kasan_poison_pages() or
264 * kasan_slab_free_mempool().
265 */
266
267 return false;
268}
269
270void __kasan_kfree_large(void *ptr, unsigned long ip)
271{
272 ____kasan_kfree_large(ptr, ip);
273}
274
275void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
276{
277 struct folio *folio;
278
279 folio = virt_to_folio(ptr);
280
281 /*
282 * Even though this function is only called for kmem_cache_alloc and
283 * kmalloc backed mempool allocations, those allocations can still be
284 * !PageSlab() when the size provided to kmalloc is larger than
285 * KMALLOC_MAX_SIZE, and kmalloc falls back onto page_alloc.
286 */
287 if (unlikely(!folio_test_slab(folio))) {
288 if (____kasan_kfree_large(ptr, ip))
289 return;
290 kasan_poison(ptr, folio_size(folio), KASAN_PAGE_FREE, false);
291 } else {
292 struct slab *slab = folio_slab(folio);
293
294 ____kasan_slab_free(slab->slab_cache, ptr, ip, false, false);
295 }
296}
297
298void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
299 void *object, gfp_t flags, bool init)
300{
301 u8 tag;
302 void *tagged_object;
303
304 if (gfpflags_allow_blocking(flags))
305 kasan_quarantine_reduce();
306
307 if (unlikely(object == NULL))
308 return NULL;
309
310 if (is_kfence_address(object))
311 return (void *)object;
312
313 /*
314 * Generate and assign random tag for tag-based modes.
315 * Tag is ignored in set_tag() for the generic mode.
316 */
317 tag = assign_tag(cache, object, false);
318 tagged_object = set_tag(object, tag);
319
320 /*
321 * Unpoison the whole object.
322 * For kmalloc() allocations, kasan_kmalloc() will do precise poisoning.
323 */
324 kasan_unpoison(tagged_object, cache->object_size, init);
325
326 /* Save alloc info (if possible) for non-kmalloc() allocations. */
327 if (kasan_stack_collection_enabled() && !cache->kasan_info.is_kmalloc)
328 kasan_save_alloc_info(cache, tagged_object, flags);
329
330 return tagged_object;
331}
332
333static inline void *____kasan_kmalloc(struct kmem_cache *cache,
334 const void *object, size_t size, gfp_t flags)
335{
336 unsigned long redzone_start;
337 unsigned long redzone_end;
338
339 if (gfpflags_allow_blocking(flags))
340 kasan_quarantine_reduce();
341
342 if (unlikely(object == NULL))
343 return NULL;
344
345 if (is_kfence_address(kasan_reset_tag(object)))
346 return (void *)object;
347
348 /*
349 * The object has already been unpoisoned by kasan_slab_alloc() for
350 * kmalloc() or by kasan_krealloc() for krealloc().
351 */
352
353 /*
354 * The redzone has byte-level precision for the generic mode.
355 * Partially poison the last object granule to cover the unaligned
356 * part of the redzone.
357 */
358 if (IS_ENABLED(CONFIG_KASAN_GENERIC))
359 kasan_poison_last_granule((void *)object, size);
360
361 /* Poison the aligned part of the redzone. */
362 redzone_start = round_up((unsigned long)(object + size),
363 KASAN_GRANULE_SIZE);
364 redzone_end = round_up((unsigned long)(object + cache->object_size),
365 KASAN_GRANULE_SIZE);
366 kasan_poison((void *)redzone_start, redzone_end - redzone_start,
367 KASAN_SLAB_REDZONE, false);
368
369 /*
370 * Save alloc info (if possible) for kmalloc() allocations.
371 * This also rewrites the alloc info when called from kasan_krealloc().
372 */
373 if (kasan_stack_collection_enabled() && cache->kasan_info.is_kmalloc)
374 kasan_save_alloc_info(cache, (void *)object, flags);
375
376 /* Keep the tag that was set by kasan_slab_alloc(). */
377 return (void *)object;
378}
379
380void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object,
381 size_t size, gfp_t flags)
382{
383 return ____kasan_kmalloc(cache, object, size, flags);
384}
385EXPORT_SYMBOL(__kasan_kmalloc);
386
387void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
388 gfp_t flags)
389{
390 unsigned long redzone_start;
391 unsigned long redzone_end;
392
393 if (gfpflags_allow_blocking(flags))
394 kasan_quarantine_reduce();
395
396 if (unlikely(ptr == NULL))
397 return NULL;
398
399 /*
400 * The object has already been unpoisoned by kasan_unpoison_pages() for
401 * alloc_pages() or by kasan_krealloc() for krealloc().
402 */
403
404 /*
405 * The redzone has byte-level precision for the generic mode.
406 * Partially poison the last object granule to cover the unaligned
407 * part of the redzone.
408 */
409 if (IS_ENABLED(CONFIG_KASAN_GENERIC))
410 kasan_poison_last_granule(ptr, size);
411
412 /* Poison the aligned part of the redzone. */
413 redzone_start = round_up((unsigned long)(ptr + size),
414 KASAN_GRANULE_SIZE);
415 redzone_end = (unsigned long)ptr + page_size(virt_to_page(ptr));
416 kasan_poison((void *)redzone_start, redzone_end - redzone_start,
417 KASAN_PAGE_REDZONE, false);
418
419 return (void *)ptr;
420}
421
422void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
423{
424 struct slab *slab;
425
426 if (unlikely(object == ZERO_SIZE_PTR))
427 return (void *)object;
428
429 /*
430 * Unpoison the object's data.
431 * Part of it might already have been unpoisoned, but it's unknown
432 * how big that part is.
433 */
434 kasan_unpoison(object, size, false);
435
436 slab = virt_to_slab(object);
437
438 /* Piggy-back on kmalloc() instrumentation to poison the redzone. */
439 if (unlikely(!slab))
440 return __kasan_kmalloc_large(object, size, flags);
441 else
442 return ____kasan_kmalloc(slab->slab_cache, object, size, flags);
443}
444
445bool __kasan_check_byte(const void *address, unsigned long ip)
446{
447 if (!kasan_byte_accessible(address)) {
448 kasan_report((unsigned long)address, 1, false, ip);
449 return false;
450 }
451 return true;
452}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * This file contains common KASAN code.
4 *
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 *
8 * Some code borrowed from https://github.com/xairy/kasan-prototype by
9 * Andrey Konovalov <andreyknvl@gmail.com>
10 */
11
12#include <linux/export.h>
13#include <linux/init.h>
14#include <linux/kasan.h>
15#include <linux/kernel.h>
16#include <linux/linkage.h>
17#include <linux/memblock.h>
18#include <linux/memory.h>
19#include <linux/mm.h>
20#include <linux/module.h>
21#include <linux/printk.h>
22#include <linux/sched.h>
23#include <linux/sched/task_stack.h>
24#include <linux/slab.h>
25#include <linux/stacktrace.h>
26#include <linux/string.h>
27#include <linux/types.h>
28#include <linux/bug.h>
29
30#include "kasan.h"
31#include "../slab.h"
32
33depot_stack_handle_t kasan_save_stack(gfp_t flags)
34{
35 unsigned long entries[KASAN_STACK_DEPTH];
36 unsigned int nr_entries;
37
38 nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
39 nr_entries = filter_irq_stacks(entries, nr_entries);
40 return stack_depot_save(entries, nr_entries, flags);
41}
42
43void kasan_set_track(struct kasan_track *track, gfp_t flags)
44{
45 track->pid = current->pid;
46 track->stack = kasan_save_stack(flags);
47}
48
49#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
50void kasan_enable_current(void)
51{
52 current->kasan_depth++;
53}
54EXPORT_SYMBOL(kasan_enable_current);
55
56void kasan_disable_current(void)
57{
58 current->kasan_depth--;
59}
60EXPORT_SYMBOL(kasan_disable_current);
61
62#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
63
64void __kasan_unpoison_range(const void *address, size_t size)
65{
66 kasan_unpoison(address, size, false);
67}
68
69#ifdef CONFIG_KASAN_STACK
70/* Unpoison the entire stack for a task. */
71void kasan_unpoison_task_stack(struct task_struct *task)
72{
73 void *base = task_stack_page(task);
74
75 kasan_unpoison(base, THREAD_SIZE, false);
76}
77
78/* Unpoison the stack for the current task beyond a watermark sp value. */
79asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
80{
81 /*
82 * Calculate the task stack base address. Avoid using 'current'
83 * because this function is called by early resume code which hasn't
84 * yet set up the percpu register (%gs).
85 */
86 void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
87
88 kasan_unpoison(base, watermark - base, false);
89}
90#endif /* CONFIG_KASAN_STACK */
91
92/*
93 * Only allow cache merging when stack collection is disabled and no metadata
94 * is present.
95 */
96slab_flags_t __kasan_never_merge(void)
97{
98 if (kasan_stack_collection_enabled())
99 return SLAB_KASAN;
100 return 0;
101}
102
103void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init)
104{
105 u8 tag;
106 unsigned long i;
107
108 if (unlikely(PageHighMem(page)))
109 return;
110
111 tag = kasan_random_tag();
112 for (i = 0; i < (1 << order); i++)
113 page_kasan_tag_set(page + i, tag);
114 kasan_unpoison(page_address(page), PAGE_SIZE << order, init);
115}
116
117void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
118{
119 if (likely(!PageHighMem(page)))
120 kasan_poison(page_address(page), PAGE_SIZE << order,
121 KASAN_FREE_PAGE, init);
122}
123
124/*
125 * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
126 * For larger allocations larger redzones are used.
127 */
128static inline unsigned int optimal_redzone(unsigned int object_size)
129{
130 return
131 object_size <= 64 - 16 ? 16 :
132 object_size <= 128 - 32 ? 32 :
133 object_size <= 512 - 64 ? 64 :
134 object_size <= 4096 - 128 ? 128 :
135 object_size <= (1 << 14) - 256 ? 256 :
136 object_size <= (1 << 15) - 512 ? 512 :
137 object_size <= (1 << 16) - 1024 ? 1024 : 2048;
138}
139
140void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
141 slab_flags_t *flags)
142{
143 unsigned int ok_size;
144 unsigned int optimal_size;
145
146 /*
147 * SLAB_KASAN is used to mark caches as ones that are sanitized by
148 * KASAN. Currently this flag is used in two places:
149 * 1. In slab_ksize() when calculating the size of the accessible
150 * memory within the object.
151 * 2. In slab_common.c to prevent merging of sanitized caches.
152 */
153 *flags |= SLAB_KASAN;
154
155 if (!kasan_stack_collection_enabled())
156 return;
157
158 ok_size = *size;
159
160 /* Add alloc meta into redzone. */
161 cache->kasan_info.alloc_meta_offset = *size;
162 *size += sizeof(struct kasan_alloc_meta);
163
164 /*
165 * If alloc meta doesn't fit, don't add it.
166 * This can only happen with SLAB, as it has KMALLOC_MAX_SIZE equal
167 * to KMALLOC_MAX_CACHE_SIZE and doesn't fall back to page_alloc for
168 * larger sizes.
169 */
170 if (*size > KMALLOC_MAX_SIZE) {
171 cache->kasan_info.alloc_meta_offset = 0;
172 *size = ok_size;
173 /* Continue, since free meta might still fit. */
174 }
175
176 /* Only the generic mode uses free meta or flexible redzones. */
177 if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
178 cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
179 return;
180 }
181
182 /*
183 * Add free meta into redzone when it's not possible to store
184 * it in the object. This is the case when:
185 * 1. Object is SLAB_TYPESAFE_BY_RCU, which means that it can
186 * be touched after it was freed, or
187 * 2. Object has a constructor, which means it's expected to
188 * retain its content until the next allocation, or
189 * 3. Object is too small.
190 * Otherwise cache->kasan_info.free_meta_offset = 0 is implied.
191 */
192 if ((cache->flags & SLAB_TYPESAFE_BY_RCU) || cache->ctor ||
193 cache->object_size < sizeof(struct kasan_free_meta)) {
194 ok_size = *size;
195
196 cache->kasan_info.free_meta_offset = *size;
197 *size += sizeof(struct kasan_free_meta);
198
199 /* If free meta doesn't fit, don't add it. */
200 if (*size > KMALLOC_MAX_SIZE) {
201 cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
202 *size = ok_size;
203 }
204 }
205
206 /* Calculate size with optimal redzone. */
207 optimal_size = cache->object_size + optimal_redzone(cache->object_size);
208 /* Limit it with KMALLOC_MAX_SIZE (relevant for SLAB only). */
209 if (optimal_size > KMALLOC_MAX_SIZE)
210 optimal_size = KMALLOC_MAX_SIZE;
211 /* Use optimal size if the size with added metas is not large enough. */
212 if (*size < optimal_size)
213 *size = optimal_size;
214}
215
216void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
217{
218 cache->kasan_info.is_kmalloc = true;
219}
220
221size_t __kasan_metadata_size(struct kmem_cache *cache)
222{
223 if (!kasan_stack_collection_enabled())
224 return 0;
225 return (cache->kasan_info.alloc_meta_offset ?
226 sizeof(struct kasan_alloc_meta) : 0) +
227 (cache->kasan_info.free_meta_offset ?
228 sizeof(struct kasan_free_meta) : 0);
229}
230
231struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
232 const void *object)
233{
234 if (!cache->kasan_info.alloc_meta_offset)
235 return NULL;
236 return kasan_reset_tag(object) + cache->kasan_info.alloc_meta_offset;
237}
238
239#ifdef CONFIG_KASAN_GENERIC
240struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
241 const void *object)
242{
243 BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
244 if (cache->kasan_info.free_meta_offset == KASAN_NO_FREE_META)
245 return NULL;
246 return kasan_reset_tag(object) + cache->kasan_info.free_meta_offset;
247}
248#endif
249
250void __kasan_poison_slab(struct page *page)
251{
252 unsigned long i;
253
254 for (i = 0; i < compound_nr(page); i++)
255 page_kasan_tag_reset(page + i);
256 kasan_poison(page_address(page), page_size(page),
257 KASAN_KMALLOC_REDZONE, false);
258}
259
260void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
261{
262 kasan_unpoison(object, cache->object_size, false);
263}
264
265void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
266{
267 kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
268 KASAN_KMALLOC_REDZONE, false);
269}
270
271/*
272 * This function assigns a tag to an object considering the following:
273 * 1. A cache might have a constructor, which might save a pointer to a slab
274 * object somewhere (e.g. in the object itself). We preassign a tag for
275 * each object in caches with constructors during slab creation and reuse
276 * the same tag each time a particular object is allocated.
277 * 2. A cache might be SLAB_TYPESAFE_BY_RCU, which means objects can be
278 * accessed after being freed. We preassign tags for objects in these
279 * caches as well.
280 * 3. For SLAB allocator we can't preassign tags randomly since the freelist
281 * is stored as an array of indexes instead of a linked list. Assign tags
282 * based on objects indexes, so that objects that are next to each other
283 * get different tags.
284 */
285static inline u8 assign_tag(struct kmem_cache *cache,
286 const void *object, bool init)
287{
288 if (IS_ENABLED(CONFIG_KASAN_GENERIC))
289 return 0xff;
290
291 /*
292 * If the cache neither has a constructor nor has SLAB_TYPESAFE_BY_RCU
293 * set, assign a tag when the object is being allocated (init == false).
294 */
295 if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU))
296 return init ? KASAN_TAG_KERNEL : kasan_random_tag();
297
298 /* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU: */
299#ifdef CONFIG_SLAB
300 /* For SLAB assign tags based on the object index in the freelist. */
301 return (u8)obj_to_index(cache, virt_to_page(object), (void *)object);
302#else
303 /*
304 * For SLUB assign a random tag during slab creation, otherwise reuse
305 * the already assigned tag.
306 */
307 return init ? kasan_random_tag() : get_tag(object);
308#endif
309}
310
311void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
312 const void *object)
313{
314 struct kasan_alloc_meta *alloc_meta;
315
316 if (kasan_stack_collection_enabled()) {
317 alloc_meta = kasan_get_alloc_meta(cache, object);
318 if (alloc_meta)
319 __memset(alloc_meta, 0, sizeof(*alloc_meta));
320 }
321
322 /* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
323 object = set_tag(object, assign_tag(cache, object, true));
324
325 return (void *)object;
326}
327
328static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
329 unsigned long ip, bool quarantine, bool init)
330{
331 u8 tag;
332 void *tagged_object;
333
334 if (!kasan_arch_is_ready())
335 return false;
336
337 tag = get_tag(object);
338 tagged_object = object;
339 object = kasan_reset_tag(object);
340
341 if (is_kfence_address(object))
342 return false;
343
344 if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) !=
345 object)) {
346 kasan_report_invalid_free(tagged_object, ip);
347 return true;
348 }
349
350 /* RCU slabs could be legally used after free within the RCU period */
351 if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
352 return false;
353
354 if (!kasan_byte_accessible(tagged_object)) {
355 kasan_report_invalid_free(tagged_object, ip);
356 return true;
357 }
358
359 kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
360 KASAN_KMALLOC_FREE, init);
361
362 if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine))
363 return false;
364
365 if (kasan_stack_collection_enabled())
366 kasan_set_free_info(cache, object, tag);
367
368 return kasan_quarantine_put(cache, object);
369}
370
371bool __kasan_slab_free(struct kmem_cache *cache, void *object,
372 unsigned long ip, bool init)
373{
374 return ____kasan_slab_free(cache, object, ip, true, init);
375}
376
377static inline bool ____kasan_kfree_large(void *ptr, unsigned long ip)
378{
379 if (ptr != page_address(virt_to_head_page(ptr))) {
380 kasan_report_invalid_free(ptr, ip);
381 return true;
382 }
383
384 if (!kasan_byte_accessible(ptr)) {
385 kasan_report_invalid_free(ptr, ip);
386 return true;
387 }
388
389 /*
390 * The object will be poisoned by kasan_free_pages() or
391 * kasan_slab_free_mempool().
392 */
393
394 return false;
395}
396
397void __kasan_kfree_large(void *ptr, unsigned long ip)
398{
399 ____kasan_kfree_large(ptr, ip);
400}
401
402void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
403{
404 struct page *page;
405
406 page = virt_to_head_page(ptr);
407
408 /*
409 * Even though this function is only called for kmem_cache_alloc and
410 * kmalloc backed mempool allocations, those allocations can still be
411 * !PageSlab() when the size provided to kmalloc is larger than
412 * KMALLOC_MAX_SIZE, and kmalloc falls back onto page_alloc.
413 */
414 if (unlikely(!PageSlab(page))) {
415 if (____kasan_kfree_large(ptr, ip))
416 return;
417 kasan_poison(ptr, page_size(page), KASAN_FREE_PAGE, false);
418 } else {
419 ____kasan_slab_free(page->slab_cache, ptr, ip, false, false);
420 }
421}
422
423static void set_alloc_info(struct kmem_cache *cache, void *object,
424 gfp_t flags, bool is_kmalloc)
425{
426 struct kasan_alloc_meta *alloc_meta;
427
428 /* Don't save alloc info for kmalloc caches in kasan_slab_alloc(). */
429 if (cache->kasan_info.is_kmalloc && !is_kmalloc)
430 return;
431
432 alloc_meta = kasan_get_alloc_meta(cache, object);
433 if (alloc_meta)
434 kasan_set_track(&alloc_meta->alloc_track, flags);
435}
436
437void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
438 void *object, gfp_t flags, bool init)
439{
440 u8 tag;
441 void *tagged_object;
442
443 if (gfpflags_allow_blocking(flags))
444 kasan_quarantine_reduce();
445
446 if (unlikely(object == NULL))
447 return NULL;
448
449 if (is_kfence_address(object))
450 return (void *)object;
451
452 /*
453 * Generate and assign random tag for tag-based modes.
454 * Tag is ignored in set_tag() for the generic mode.
455 */
456 tag = assign_tag(cache, object, false);
457 tagged_object = set_tag(object, tag);
458
459 /*
460 * Unpoison the whole object.
461 * For kmalloc() allocations, kasan_kmalloc() will do precise poisoning.
462 */
463 kasan_unpoison(tagged_object, cache->object_size, init);
464
465 /* Save alloc info (if possible) for non-kmalloc() allocations. */
466 if (kasan_stack_collection_enabled())
467 set_alloc_info(cache, (void *)object, flags, false);
468
469 return tagged_object;
470}
471
472static inline void *____kasan_kmalloc(struct kmem_cache *cache,
473 const void *object, size_t size, gfp_t flags)
474{
475 unsigned long redzone_start;
476 unsigned long redzone_end;
477
478 if (gfpflags_allow_blocking(flags))
479 kasan_quarantine_reduce();
480
481 if (unlikely(object == NULL))
482 return NULL;
483
484 if (is_kfence_address(kasan_reset_tag(object)))
485 return (void *)object;
486
487 /*
488 * The object has already been unpoisoned by kasan_slab_alloc() for
489 * kmalloc() or by kasan_krealloc() for krealloc().
490 */
491
492 /*
493 * The redzone has byte-level precision for the generic mode.
494 * Partially poison the last object granule to cover the unaligned
495 * part of the redzone.
496 */
497 if (IS_ENABLED(CONFIG_KASAN_GENERIC))
498 kasan_poison_last_granule((void *)object, size);
499
500 /* Poison the aligned part of the redzone. */
501 redzone_start = round_up((unsigned long)(object + size),
502 KASAN_GRANULE_SIZE);
503 redzone_end = round_up((unsigned long)(object + cache->object_size),
504 KASAN_GRANULE_SIZE);
505 kasan_poison((void *)redzone_start, redzone_end - redzone_start,
506 KASAN_KMALLOC_REDZONE, false);
507
508 /*
509 * Save alloc info (if possible) for kmalloc() allocations.
510 * This also rewrites the alloc info when called from kasan_krealloc().
511 */
512 if (kasan_stack_collection_enabled())
513 set_alloc_info(cache, (void *)object, flags, true);
514
515 /* Keep the tag that was set by kasan_slab_alloc(). */
516 return (void *)object;
517}
518
519void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object,
520 size_t size, gfp_t flags)
521{
522 return ____kasan_kmalloc(cache, object, size, flags);
523}
524EXPORT_SYMBOL(__kasan_kmalloc);
525
526void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
527 gfp_t flags)
528{
529 unsigned long redzone_start;
530 unsigned long redzone_end;
531
532 if (gfpflags_allow_blocking(flags))
533 kasan_quarantine_reduce();
534
535 if (unlikely(ptr == NULL))
536 return NULL;
537
538 /*
539 * The object has already been unpoisoned by kasan_alloc_pages() for
540 * alloc_pages() or by kasan_krealloc() for krealloc().
541 */
542
543 /*
544 * The redzone has byte-level precision for the generic mode.
545 * Partially poison the last object granule to cover the unaligned
546 * part of the redzone.
547 */
548 if (IS_ENABLED(CONFIG_KASAN_GENERIC))
549 kasan_poison_last_granule(ptr, size);
550
551 /* Poison the aligned part of the redzone. */
552 redzone_start = round_up((unsigned long)(ptr + size),
553 KASAN_GRANULE_SIZE);
554 redzone_end = (unsigned long)ptr + page_size(virt_to_page(ptr));
555 kasan_poison((void *)redzone_start, redzone_end - redzone_start,
556 KASAN_PAGE_REDZONE, false);
557
558 return (void *)ptr;
559}
560
561void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
562{
563 struct page *page;
564
565 if (unlikely(object == ZERO_SIZE_PTR))
566 return (void *)object;
567
568 /*
569 * Unpoison the object's data.
570 * Part of it might already have been unpoisoned, but it's unknown
571 * how big that part is.
572 */
573 kasan_unpoison(object, size, false);
574
575 page = virt_to_head_page(object);
576
577 /* Piggy-back on kmalloc() instrumentation to poison the redzone. */
578 if (unlikely(!PageSlab(page)))
579 return __kasan_kmalloc_large(object, size, flags);
580 else
581 return ____kasan_kmalloc(page->slab_cache, object, size, flags);
582}
583
584bool __kasan_check_byte(const void *address, unsigned long ip)
585{
586 if (!kasan_byte_accessible(address)) {
587 kasan_report((unsigned long)address, 1, false, ip);
588 return false;
589 }
590 return true;
591}