1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Slab allocator functions that are independent of the allocator strategy
4 *
5 * (C) 2012 Christoph Lameter <cl@linux.com>
6 */
7 #include <linux/slab.h>
8
9 #include <linux/mm.h>
10 #include <linux/poison.h>
11 #include <linux/interrupt.h>
12 #include <linux/memory.h>
13 #include <linux/cache.h>
14 #include <linux/compiler.h>
15 #include <linux/kfence.h>
16 #include <linux/module.h>
17 #include <linux/cpu.h>
18 #include <linux/uaccess.h>
19 #include <linux/seq_file.h>
20 #include <linux/dma-mapping.h>
21 #include <linux/swiotlb.h>
22 #include <linux/proc_fs.h>
23 #include <linux/debugfs.h>
24 #include <linux/kmemleak.h>
25 #include <linux/kasan.h>
26 #include <asm/cacheflush.h>
27 #include <asm/tlbflush.h>
28 #include <asm/page.h>
29 #include <linux/memcontrol.h>
30 #include <linux/stackdepot.h>
31
32 #include "internal.h"
33 #include "slab.h"
34
35 #define CREATE_TRACE_POINTS
36 #include <trace/events/kmem.h>
37
38 enum slab_state slab_state;
39 LIST_HEAD(slab_caches);
40 DEFINE_MUTEX(slab_mutex);
41 struct kmem_cache *kmem_cache;
42
43 /*
44 * Set of flags that will prevent slab merging
45 */
46 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
47 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
48 SLAB_FAILSLAB | SLAB_NO_MERGE)
49
50 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
51 SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
52
53 /*
54 * Merge control. If this is set then no merging of slab caches will occur.
55 */
56 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT);
57
setup_slab_nomerge(char * str)58 static int __init setup_slab_nomerge(char *str)
59 {
60 slab_nomerge = true;
61 return 1;
62 }
63
setup_slab_merge(char * str)64 static int __init setup_slab_merge(char *str)
65 {
66 slab_nomerge = false;
67 return 1;
68 }
69
70 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
71 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0);
72
73 __setup("slab_nomerge", setup_slab_nomerge);
74 __setup("slab_merge", setup_slab_merge);
75
76 /*
77 * Determine the size of a slab object
78 */
kmem_cache_size(struct kmem_cache * s)79 unsigned int kmem_cache_size(struct kmem_cache *s)
80 {
81 return s->object_size;
82 }
83 EXPORT_SYMBOL(kmem_cache_size);
84
85 #ifdef CONFIG_DEBUG_VM
86
kmem_cache_is_duplicate_name(const char * name)87 static bool kmem_cache_is_duplicate_name(const char *name)
88 {
89 struct kmem_cache *s;
90
91 list_for_each_entry(s, &slab_caches, list) {
92 if (!strcmp(s->name, name))
93 return true;
94 }
95
96 return false;
97 }
98
kmem_cache_sanity_check(const char * name,unsigned int size)99 static int kmem_cache_sanity_check(const char *name, unsigned int size)
100 {
101 if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) {
102 pr_err("kmem_cache_create(%s) integrity check failed\n", name);
103 return -EINVAL;
104 }
105
106 /* Duplicate names will confuse slabtop, et al */
107 WARN(kmem_cache_is_duplicate_name(name),
108 "kmem_cache of name '%s' already exists\n", name);
109
110 WARN_ON(strchr(name, ' ')); /* It confuses parsers */
111 return 0;
112 }
113 #else
kmem_cache_sanity_check(const char * name,unsigned int size)114 static inline int kmem_cache_sanity_check(const char *name, unsigned int size)
115 {
116 return 0;
117 }
118 #endif
119
120 /*
121 * Figure out what the alignment of the objects will be given a set of
122 * flags, a user specified alignment and the size of the objects.
123 */
calculate_alignment(slab_flags_t flags,unsigned int align,unsigned int size)124 static unsigned int calculate_alignment(slab_flags_t flags,
125 unsigned int align, unsigned int size)
126 {
127 /*
128 * If the user wants hardware cache aligned objects then follow that
129 * suggestion if the object is sufficiently large.
130 *
131 * The hardware cache alignment cannot override the specified
132 * alignment though. If that is greater then use it.
133 */
134 if (flags & SLAB_HWCACHE_ALIGN) {
135 unsigned int ralign;
136
137 ralign = cache_line_size();
138 while (size <= ralign / 2)
139 ralign /= 2;
140 align = max(align, ralign);
141 }
142
143 align = max(align, arch_slab_minalign());
144
145 return ALIGN(align, sizeof(void *));
146 }
147
148 /*
149 * Find a mergeable slab cache
150 */
slab_unmergeable(struct kmem_cache * s)151 int slab_unmergeable(struct kmem_cache *s)
152 {
153 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
154 return 1;
155
156 if (s->ctor)
157 return 1;
158
159 #ifdef CONFIG_HARDENED_USERCOPY
160 if (s->usersize)
161 return 1;
162 #endif
163
164 /*
165 * We may have set a slab to be unmergeable during bootstrap.
166 */
167 if (s->refcount < 0)
168 return 1;
169
170 return 0;
171 }
172
find_mergeable(unsigned int size,unsigned int align,slab_flags_t flags,const char * name,void (* ctor)(void *))173 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
174 slab_flags_t flags, const char *name, void (*ctor)(void *))
175 {
176 struct kmem_cache *s;
177
178 if (slab_nomerge)
179 return NULL;
180
181 if (ctor)
182 return NULL;
183
184 flags = kmem_cache_flags(flags, name);
185
186 if (flags & SLAB_NEVER_MERGE)
187 return NULL;
188
189 size = ALIGN(size, sizeof(void *));
190 align = calculate_alignment(flags, align, size);
191 size = ALIGN(size, align);
192
193 list_for_each_entry_reverse(s, &slab_caches, list) {
194 if (slab_unmergeable(s))
195 continue;
196
197 if (size > s->size)
198 continue;
199
200 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
201 continue;
202 /*
203 * Check if alignment is compatible.
204 * Courtesy of Adrian Drzewiecki
205 */
206 if ((s->size & ~(align - 1)) != s->size)
207 continue;
208
209 if (s->size - size >= sizeof(void *))
210 continue;
211
212 return s;
213 }
214 return NULL;
215 }
216
create_cache(const char * name,unsigned int object_size,struct kmem_cache_args * args,slab_flags_t flags)217 static struct kmem_cache *create_cache(const char *name,
218 unsigned int object_size,
219 struct kmem_cache_args *args,
220 slab_flags_t flags)
221 {
222 struct kmem_cache *s;
223 int err;
224
225 if (WARN_ON(args->useroffset + args->usersize > object_size))
226 args->useroffset = args->usersize = 0;
227
228 /* If a custom freelist pointer is requested make sure it's sane. */
229 err = -EINVAL;
230 if (args->use_freeptr_offset &&
231 (args->freeptr_offset >= object_size ||
232 !(flags & SLAB_TYPESAFE_BY_RCU) ||
233 !IS_ALIGNED(args->freeptr_offset, sizeof(freeptr_t))))
234 goto out;
235
236 err = -ENOMEM;
237 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
238 if (!s)
239 goto out;
240 err = do_kmem_cache_create(s, name, object_size, args, flags);
241 if (err)
242 goto out_free_cache;
243
244 s->refcount = 1;
245 list_add(&s->list, &slab_caches);
246 return s;
247
248 out_free_cache:
249 kmem_cache_free(kmem_cache, s);
250 out:
251 return ERR_PTR(err);
252 }
253
254 /**
255 * __kmem_cache_create_args - Create a kmem cache.
256 * @name: A string which is used in /proc/slabinfo to identify this cache.
257 * @object_size: The size of objects to be created in this cache.
258 * @args: Additional arguments for the cache creation (see
259 * &struct kmem_cache_args).
260 * @flags: See %SLAB_* flags for an explanation of individual @flags.
261 *
262 * Not to be called directly, use the kmem_cache_create() wrapper with the same
263 * parameters.
264 *
265 * Context: Cannot be called within a interrupt, but can be interrupted.
266 *
267 * Return: a pointer to the cache on success, NULL on failure.
268 */
__kmem_cache_create_args(const char * name,unsigned int object_size,struct kmem_cache_args * args,slab_flags_t flags)269 struct kmem_cache *__kmem_cache_create_args(const char *name,
270 unsigned int object_size,
271 struct kmem_cache_args *args,
272 slab_flags_t flags)
273 {
274 struct kmem_cache *s = NULL;
275 const char *cache_name;
276 int err;
277
278 #ifdef CONFIG_SLUB_DEBUG
279 /*
280 * If no slab_debug was enabled globally, the static key is not yet
281 * enabled by setup_slub_debug(). Enable it if the cache is being
282 * created with any of the debugging flags passed explicitly.
283 * It's also possible that this is the first cache created with
284 * SLAB_STORE_USER and we should init stack_depot for it.
285 */
286 if (flags & SLAB_DEBUG_FLAGS)
287 static_branch_enable(&slub_debug_enabled);
288 if (flags & SLAB_STORE_USER)
289 stack_depot_init();
290 #endif
291
292 mutex_lock(&slab_mutex);
293
294 err = kmem_cache_sanity_check(name, object_size);
295 if (err) {
296 goto out_unlock;
297 }
298
299 /* Refuse requests with allocator specific flags */
300 if (flags & ~SLAB_FLAGS_PERMITTED) {
301 err = -EINVAL;
302 goto out_unlock;
303 }
304
305 /*
306 * Some allocators will constraint the set of valid flags to a subset
307 * of all flags. We expect them to define CACHE_CREATE_MASK in this
308 * case, and we'll just provide them with a sanitized version of the
309 * passed flags.
310 */
311 flags &= CACHE_CREATE_MASK;
312
313 /* Fail closed on bad usersize of useroffset values. */
314 if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) ||
315 WARN_ON(!args->usersize && args->useroffset) ||
316 WARN_ON(object_size < args->usersize ||
317 object_size - args->usersize < args->useroffset))
318 args->usersize = args->useroffset = 0;
319
320 if (!args->usersize)
321 s = __kmem_cache_alias(name, object_size, args->align, flags,
322 args->ctor);
323 if (s)
324 goto out_unlock;
325
326 cache_name = kstrdup_const(name, GFP_KERNEL);
327 if (!cache_name) {
328 err = -ENOMEM;
329 goto out_unlock;
330 }
331
332 args->align = calculate_alignment(flags, args->align, object_size);
333 s = create_cache(cache_name, object_size, args, flags);
334 if (IS_ERR(s)) {
335 err = PTR_ERR(s);
336 kfree_const(cache_name);
337 }
338
339 out_unlock:
340 mutex_unlock(&slab_mutex);
341
342 if (err) {
343 if (flags & SLAB_PANIC)
344 panic("%s: Failed to create slab '%s'. Error %d\n",
345 __func__, name, err);
346 else {
347 pr_warn("%s(%s) failed with error %d\n",
348 __func__, name, err);
349 dump_stack();
350 }
351 return NULL;
352 }
353 return s;
354 }
355 EXPORT_SYMBOL(__kmem_cache_create_args);
356
357 static struct kmem_cache *kmem_buckets_cache __ro_after_init;
358
359 /**
360 * kmem_buckets_create - Create a set of caches that handle dynamic sized
361 * allocations via kmem_buckets_alloc()
362 * @name: A prefix string which is used in /proc/slabinfo to identify this
363 * cache. The individual caches with have their sizes as the suffix.
364 * @flags: SLAB flags (see kmem_cache_create() for details).
365 * @useroffset: Starting offset within an allocation that may be copied
366 * to/from userspace.
367 * @usersize: How many bytes, starting at @useroffset, may be copied
368 * to/from userspace.
369 * @ctor: A constructor for the objects, run when new allocations are made.
370 *
371 * Cannot be called within an interrupt, but can be interrupted.
372 *
373 * Return: a pointer to the cache on success, NULL on failure. When
374 * CONFIG_SLAB_BUCKETS is not enabled, ZERO_SIZE_PTR is returned, and
375 * subsequent calls to kmem_buckets_alloc() will fall back to kmalloc().
376 * (i.e. callers only need to check for NULL on failure.)
377 */
kmem_buckets_create(const char * name,slab_flags_t flags,unsigned int useroffset,unsigned int usersize,void (* ctor)(void *))378 kmem_buckets *kmem_buckets_create(const char *name, slab_flags_t flags,
379 unsigned int useroffset,
380 unsigned int usersize,
381 void (*ctor)(void *))
382 {
383 kmem_buckets *b;
384 int idx;
385
386 /*
387 * When the separate buckets API is not built in, just return
388 * a non-NULL value for the kmem_buckets pointer, which will be
389 * unused when performing allocations.
390 */
391 if (!IS_ENABLED(CONFIG_SLAB_BUCKETS))
392 return ZERO_SIZE_PTR;
393
394 if (WARN_ON(!kmem_buckets_cache))
395 return NULL;
396
397 b = kmem_cache_alloc(kmem_buckets_cache, GFP_KERNEL|__GFP_ZERO);
398 if (WARN_ON(!b))
399 return NULL;
400
401 flags |= SLAB_NO_MERGE;
402
403 for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) {
404 char *short_size, *cache_name;
405 unsigned int cache_useroffset, cache_usersize;
406 unsigned int size;
407
408 if (!kmalloc_caches[KMALLOC_NORMAL][idx])
409 continue;
410
411 size = kmalloc_caches[KMALLOC_NORMAL][idx]->object_size;
412 if (!size)
413 continue;
414
415 short_size = strchr(kmalloc_caches[KMALLOC_NORMAL][idx]->name, '-');
416 if (WARN_ON(!short_size))
417 goto fail;
418
419 cache_name = kasprintf(GFP_KERNEL, "%s-%s", name, short_size + 1);
420 if (WARN_ON(!cache_name))
421 goto fail;
422
423 if (useroffset >= size) {
424 cache_useroffset = 0;
425 cache_usersize = 0;
426 } else {
427 cache_useroffset = useroffset;
428 cache_usersize = min(size - cache_useroffset, usersize);
429 }
430 (*b)[idx] = kmem_cache_create_usercopy(cache_name, size,
431 0, flags, cache_useroffset,
432 cache_usersize, ctor);
433 kfree(cache_name);
434 if (WARN_ON(!(*b)[idx]))
435 goto fail;
436 }
437
438 return b;
439
440 fail:
441 for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++)
442 kmem_cache_destroy((*b)[idx]);
443 kmem_cache_free(kmem_buckets_cache, b);
444
445 return NULL;
446 }
447 EXPORT_SYMBOL(kmem_buckets_create);
448
449 /*
450 * For a given kmem_cache, kmem_cache_destroy() should only be called
451 * once or there will be a use-after-free problem. The actual deletion
452 * and release of the kobject does not need slab_mutex or cpu_hotplug_lock
453 * protection. So they are now done without holding those locks.
454 */
kmem_cache_release(struct kmem_cache * s)455 static void kmem_cache_release(struct kmem_cache *s)
456 {
457 kfence_shutdown_cache(s);
458 if (__is_defined(SLAB_SUPPORTS_SYSFS) && slab_state >= FULL)
459 sysfs_slab_release(s);
460 else
461 slab_kmem_cache_release(s);
462 }
463
slab_kmem_cache_release(struct kmem_cache * s)464 void slab_kmem_cache_release(struct kmem_cache *s)
465 {
466 __kmem_cache_release(s);
467 kfree_const(s->name);
468 kmem_cache_free(kmem_cache, s);
469 }
470
kmem_cache_destroy(struct kmem_cache * s)471 void kmem_cache_destroy(struct kmem_cache *s)
472 {
473 int err;
474
475 if (unlikely(!s) || !kasan_check_byte(s))
476 return;
477
478 /* in-flight kfree_rcu()'s may include objects from our cache */
479 kvfree_rcu_barrier();
480
481 if (IS_ENABLED(CONFIG_SLUB_RCU_DEBUG) &&
482 (s->flags & SLAB_TYPESAFE_BY_RCU)) {
483 /*
484 * Under CONFIG_SLUB_RCU_DEBUG, when objects in a
485 * SLAB_TYPESAFE_BY_RCU slab are freed, SLUB will internally
486 * defer their freeing with call_rcu().
487 * Wait for such call_rcu() invocations here before actually
488 * destroying the cache.
489 *
490 * It doesn't matter that we haven't looked at the slab refcount
491 * yet - slabs with SLAB_TYPESAFE_BY_RCU can't be merged, so
492 * the refcount should be 1 here.
493 */
494 rcu_barrier();
495 }
496
497 cpus_read_lock();
498 mutex_lock(&slab_mutex);
499
500 s->refcount--;
501 if (s->refcount) {
502 mutex_unlock(&slab_mutex);
503 cpus_read_unlock();
504 return;
505 }
506
507 /* free asan quarantined objects */
508 kasan_cache_shutdown(s);
509
510 err = __kmem_cache_shutdown(s);
511 if (!slab_in_kunit_test())
512 WARN(err, "%s %s: Slab cache still has objects when called from %pS",
513 __func__, s->name, (void *)_RET_IP_);
514
515 list_del(&s->list);
516
517 mutex_unlock(&slab_mutex);
518 cpus_read_unlock();
519
520 if (slab_state >= FULL)
521 sysfs_slab_unlink(s);
522 debugfs_slab_release(s);
523
524 if (err)
525 return;
526
527 if (s->flags & SLAB_TYPESAFE_BY_RCU)
528 rcu_barrier();
529
530 kmem_cache_release(s);
531 }
532 EXPORT_SYMBOL(kmem_cache_destroy);
533
534 /**
535 * kmem_cache_shrink - Shrink a cache.
536 * @cachep: The cache to shrink.
537 *
538 * Releases as many slabs as possible for a cache.
539 * To help debugging, a zero exit status indicates all slabs were released.
540 *
541 * Return: %0 if all slabs were released, non-zero otherwise
542 */
kmem_cache_shrink(struct kmem_cache * cachep)543 int kmem_cache_shrink(struct kmem_cache *cachep)
544 {
545 kasan_cache_shrink(cachep);
546
547 return __kmem_cache_shrink(cachep);
548 }
549 EXPORT_SYMBOL(kmem_cache_shrink);
550
slab_is_available(void)551 bool slab_is_available(void)
552 {
553 return slab_state >= UP;
554 }
555
556 #ifdef CONFIG_PRINTK
kmem_obj_info(struct kmem_obj_info * kpp,void * object,struct slab * slab)557 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
558 {
559 if (__kfence_obj_info(kpp, object, slab))
560 return;
561 __kmem_obj_info(kpp, object, slab);
562 }
563
564 /**
565 * kmem_dump_obj - Print available slab provenance information
566 * @object: slab object for which to find provenance information.
567 *
568 * This function uses pr_cont(), so that the caller is expected to have
569 * printed out whatever preamble is appropriate. The provenance information
570 * depends on the type of object and on how much debugging is enabled.
571 * For a slab-cache object, the fact that it is a slab object is printed,
572 * and, if available, the slab name, return address, and stack trace from
573 * the allocation and last free path of that object.
574 *
575 * Return: %true if the pointer is to a not-yet-freed object from
576 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer
577 * is to an already-freed object, and %false otherwise.
578 */
kmem_dump_obj(void * object)579 bool kmem_dump_obj(void *object)
580 {
581 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
582 int i;
583 struct slab *slab;
584 unsigned long ptroffset;
585 struct kmem_obj_info kp = { };
586
587 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */
588 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object))
589 return false;
590 slab = virt_to_slab(object);
591 if (!slab)
592 return false;
593
594 kmem_obj_info(&kp, object, slab);
595 if (kp.kp_slab_cache)
596 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name);
597 else
598 pr_cont(" slab%s", cp);
599 if (is_kfence_address(object))
600 pr_cont(" (kfence)");
601 if (kp.kp_objp)
602 pr_cont(" start %px", kp.kp_objp);
603 if (kp.kp_data_offset)
604 pr_cont(" data offset %lu", kp.kp_data_offset);
605 if (kp.kp_objp) {
606 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset;
607 pr_cont(" pointer offset %lu", ptroffset);
608 }
609 if (kp.kp_slab_cache && kp.kp_slab_cache->object_size)
610 pr_cont(" size %u", kp.kp_slab_cache->object_size);
611 if (kp.kp_ret)
612 pr_cont(" allocated at %pS\n", kp.kp_ret);
613 else
614 pr_cont("\n");
615 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) {
616 if (!kp.kp_stack[i])
617 break;
618 pr_info(" %pS\n", kp.kp_stack[i]);
619 }
620
621 if (kp.kp_free_stack[0])
622 pr_cont(" Free path:\n");
623
624 for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) {
625 if (!kp.kp_free_stack[i])
626 break;
627 pr_info(" %pS\n", kp.kp_free_stack[i]);
628 }
629
630 return true;
631 }
632 EXPORT_SYMBOL_GPL(kmem_dump_obj);
633 #endif
634
635 /* Create a cache during boot when no slab services are available yet */
create_boot_cache(struct kmem_cache * s,const char * name,unsigned int size,slab_flags_t flags,unsigned int useroffset,unsigned int usersize)636 void __init create_boot_cache(struct kmem_cache *s, const char *name,
637 unsigned int size, slab_flags_t flags,
638 unsigned int useroffset, unsigned int usersize)
639 {
640 int err;
641 unsigned int align = ARCH_KMALLOC_MINALIGN;
642 struct kmem_cache_args kmem_args = {};
643
644 /*
645 * kmalloc caches guarantee alignment of at least the largest
646 * power-of-two divisor of the size. For power-of-two sizes,
647 * it is the size itself.
648 */
649 if (flags & SLAB_KMALLOC)
650 align = max(align, 1U << (ffs(size) - 1));
651 kmem_args.align = calculate_alignment(flags, align, size);
652
653 #ifdef CONFIG_HARDENED_USERCOPY
654 kmem_args.useroffset = useroffset;
655 kmem_args.usersize = usersize;
656 #endif
657
658 err = do_kmem_cache_create(s, name, size, &kmem_args, flags);
659
660 if (err)
661 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n",
662 name, size, err);
663
664 s->refcount = -1; /* Exempt from merging for now */
665 }
666
create_kmalloc_cache(const char * name,unsigned int size,slab_flags_t flags)667 static struct kmem_cache *__init create_kmalloc_cache(const char *name,
668 unsigned int size,
669 slab_flags_t flags)
670 {
671 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
672
673 if (!s)
674 panic("Out of memory when creating slab %s\n", name);
675
676 create_boot_cache(s, name, size, flags | SLAB_KMALLOC, 0, size);
677 list_add(&s->list, &slab_caches);
678 s->refcount = 1;
679 return s;
680 }
681
682 kmem_buckets kmalloc_caches[NR_KMALLOC_TYPES] __ro_after_init =
683 { /* initialization for https://llvm.org/pr42570 */ };
684 EXPORT_SYMBOL(kmalloc_caches);
685
686 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
687 unsigned long random_kmalloc_seed __ro_after_init;
688 EXPORT_SYMBOL(random_kmalloc_seed);
689 #endif
690
691 /*
692 * Conversion table for small slabs sizes / 8 to the index in the
693 * kmalloc array. This is necessary for slabs < 192 since we have non power
694 * of two cache sizes there. The size of larger slabs can be determined using
695 * fls.
696 */
697 u8 kmalloc_size_index[24] __ro_after_init = {
698 3, /* 8 */
699 4, /* 16 */
700 5, /* 24 */
701 5, /* 32 */
702 6, /* 40 */
703 6, /* 48 */
704 6, /* 56 */
705 6, /* 64 */
706 1, /* 72 */
707 1, /* 80 */
708 1, /* 88 */
709 1, /* 96 */
710 7, /* 104 */
711 7, /* 112 */
712 7, /* 120 */
713 7, /* 128 */
714 2, /* 136 */
715 2, /* 144 */
716 2, /* 152 */
717 2, /* 160 */
718 2, /* 168 */
719 2, /* 176 */
720 2, /* 184 */
721 2 /* 192 */
722 };
723
kmalloc_size_roundup(size_t size)724 size_t kmalloc_size_roundup(size_t size)
725 {
726 if (size && size <= KMALLOC_MAX_CACHE_SIZE) {
727 /*
728 * The flags don't matter since size_index is common to all.
729 * Neither does the caller for just getting ->object_size.
730 */
731 return kmalloc_slab(size, NULL, GFP_KERNEL, 0)->object_size;
732 }
733
734 /* Above the smaller buckets, size is a multiple of page size. */
735 if (size && size <= KMALLOC_MAX_SIZE)
736 return PAGE_SIZE << get_order(size);
737
738 /*
739 * Return 'size' for 0 - kmalloc() returns ZERO_SIZE_PTR
740 * and very large size - kmalloc() may fail.
741 */
742 return size;
743
744 }
745 EXPORT_SYMBOL(kmalloc_size_roundup);
746
747 #ifdef CONFIG_ZONE_DMA
748 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz,
749 #else
750 #define KMALLOC_DMA_NAME(sz)
751 #endif
752
753 #ifdef CONFIG_MEMCG
754 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz,
755 #else
756 #define KMALLOC_CGROUP_NAME(sz)
757 #endif
758
759 #ifndef CONFIG_SLUB_TINY
760 #define KMALLOC_RCL_NAME(sz) .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz,
761 #else
762 #define KMALLOC_RCL_NAME(sz)
763 #endif
764
765 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
766 #define __KMALLOC_RANDOM_CONCAT(a, b) a ## b
767 #define KMALLOC_RANDOM_NAME(N, sz) __KMALLOC_RANDOM_CONCAT(KMA_RAND_, N)(sz)
768 #define KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 1] = "kmalloc-rnd-01-" #sz,
769 #define KMA_RAND_2(sz) KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 2] = "kmalloc-rnd-02-" #sz,
770 #define KMA_RAND_3(sz) KMA_RAND_2(sz) .name[KMALLOC_RANDOM_START + 3] = "kmalloc-rnd-03-" #sz,
771 #define KMA_RAND_4(sz) KMA_RAND_3(sz) .name[KMALLOC_RANDOM_START + 4] = "kmalloc-rnd-04-" #sz,
772 #define KMA_RAND_5(sz) KMA_RAND_4(sz) .name[KMALLOC_RANDOM_START + 5] = "kmalloc-rnd-05-" #sz,
773 #define KMA_RAND_6(sz) KMA_RAND_5(sz) .name[KMALLOC_RANDOM_START + 6] = "kmalloc-rnd-06-" #sz,
774 #define KMA_RAND_7(sz) KMA_RAND_6(sz) .name[KMALLOC_RANDOM_START + 7] = "kmalloc-rnd-07-" #sz,
775 #define KMA_RAND_8(sz) KMA_RAND_7(sz) .name[KMALLOC_RANDOM_START + 8] = "kmalloc-rnd-08-" #sz,
776 #define KMA_RAND_9(sz) KMA_RAND_8(sz) .name[KMALLOC_RANDOM_START + 9] = "kmalloc-rnd-09-" #sz,
777 #define KMA_RAND_10(sz) KMA_RAND_9(sz) .name[KMALLOC_RANDOM_START + 10] = "kmalloc-rnd-10-" #sz,
778 #define KMA_RAND_11(sz) KMA_RAND_10(sz) .name[KMALLOC_RANDOM_START + 11] = "kmalloc-rnd-11-" #sz,
779 #define KMA_RAND_12(sz) KMA_RAND_11(sz) .name[KMALLOC_RANDOM_START + 12] = "kmalloc-rnd-12-" #sz,
780 #define KMA_RAND_13(sz) KMA_RAND_12(sz) .name[KMALLOC_RANDOM_START + 13] = "kmalloc-rnd-13-" #sz,
781 #define KMA_RAND_14(sz) KMA_RAND_13(sz) .name[KMALLOC_RANDOM_START + 14] = "kmalloc-rnd-14-" #sz,
782 #define KMA_RAND_15(sz) KMA_RAND_14(sz) .name[KMALLOC_RANDOM_START + 15] = "kmalloc-rnd-15-" #sz,
783 #else // CONFIG_RANDOM_KMALLOC_CACHES
784 #define KMALLOC_RANDOM_NAME(N, sz)
785 #endif
786
787 #define INIT_KMALLOC_INFO(__size, __short_size) \
788 { \
789 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \
790 KMALLOC_RCL_NAME(__short_size) \
791 KMALLOC_CGROUP_NAME(__short_size) \
792 KMALLOC_DMA_NAME(__short_size) \
793 KMALLOC_RANDOM_NAME(RANDOM_KMALLOC_CACHES_NR, __short_size) \
794 .size = __size, \
795 }
796
797 /*
798 * kmalloc_info[] is to make slab_debug=,kmalloc-xx option work at boot time.
799 * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is
800 * kmalloc-2M.
801 */
802 const struct kmalloc_info_struct kmalloc_info[] __initconst = {
803 INIT_KMALLOC_INFO(0, 0),
804 INIT_KMALLOC_INFO(96, 96),
805 INIT_KMALLOC_INFO(192, 192),
806 INIT_KMALLOC_INFO(8, 8),
807 INIT_KMALLOC_INFO(16, 16),
808 INIT_KMALLOC_INFO(32, 32),
809 INIT_KMALLOC_INFO(64, 64),
810 INIT_KMALLOC_INFO(128, 128),
811 INIT_KMALLOC_INFO(256, 256),
812 INIT_KMALLOC_INFO(512, 512),
813 INIT_KMALLOC_INFO(1024, 1k),
814 INIT_KMALLOC_INFO(2048, 2k),
815 INIT_KMALLOC_INFO(4096, 4k),
816 INIT_KMALLOC_INFO(8192, 8k),
817 INIT_KMALLOC_INFO(16384, 16k),
818 INIT_KMALLOC_INFO(32768, 32k),
819 INIT_KMALLOC_INFO(65536, 64k),
820 INIT_KMALLOC_INFO(131072, 128k),
821 INIT_KMALLOC_INFO(262144, 256k),
822 INIT_KMALLOC_INFO(524288, 512k),
823 INIT_KMALLOC_INFO(1048576, 1M),
824 INIT_KMALLOC_INFO(2097152, 2M)
825 };
826
827 /*
828 * Patch up the size_index table if we have strange large alignment
829 * requirements for the kmalloc array. This is only the case for
830 * MIPS it seems. The standard arches will not generate any code here.
831 *
832 * Largest permitted alignment is 256 bytes due to the way we
833 * handle the index determination for the smaller caches.
834 *
835 * Make sure that nothing crazy happens if someone starts tinkering
836 * around with ARCH_KMALLOC_MINALIGN
837 */
setup_kmalloc_cache_index_table(void)838 void __init setup_kmalloc_cache_index_table(void)
839 {
840 unsigned int i;
841
842 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
843 !is_power_of_2(KMALLOC_MIN_SIZE));
844
845 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
846 unsigned int elem = size_index_elem(i);
847
848 if (elem >= ARRAY_SIZE(kmalloc_size_index))
849 break;
850 kmalloc_size_index[elem] = KMALLOC_SHIFT_LOW;
851 }
852
853 if (KMALLOC_MIN_SIZE >= 64) {
854 /*
855 * The 96 byte sized cache is not used if the alignment
856 * is 64 byte.
857 */
858 for (i = 64 + 8; i <= 96; i += 8)
859 kmalloc_size_index[size_index_elem(i)] = 7;
860
861 }
862
863 if (KMALLOC_MIN_SIZE >= 128) {
864 /*
865 * The 192 byte sized cache is not used if the alignment
866 * is 128 byte. Redirect kmalloc to use the 256 byte cache
867 * instead.
868 */
869 for (i = 128 + 8; i <= 192; i += 8)
870 kmalloc_size_index[size_index_elem(i)] = 8;
871 }
872 }
873
__kmalloc_minalign(void)874 static unsigned int __kmalloc_minalign(void)
875 {
876 unsigned int minalign = dma_get_cache_alignment();
877
878 if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) &&
879 is_swiotlb_allocated())
880 minalign = ARCH_KMALLOC_MINALIGN;
881
882 return max(minalign, arch_slab_minalign());
883 }
884
885 static void __init
new_kmalloc_cache(int idx,enum kmalloc_cache_type type)886 new_kmalloc_cache(int idx, enum kmalloc_cache_type type)
887 {
888 slab_flags_t flags = 0;
889 unsigned int minalign = __kmalloc_minalign();
890 unsigned int aligned_size = kmalloc_info[idx].size;
891 int aligned_idx = idx;
892
893 if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
894 flags |= SLAB_RECLAIM_ACCOUNT;
895 } else if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_CGROUP)) {
896 if (mem_cgroup_kmem_disabled()) {
897 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx];
898 return;
899 }
900 flags |= SLAB_ACCOUNT;
901 } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) {
902 flags |= SLAB_CACHE_DMA;
903 }
904
905 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
906 if (type >= KMALLOC_RANDOM_START && type <= KMALLOC_RANDOM_END)
907 flags |= SLAB_NO_MERGE;
908 #endif
909
910 /*
911 * If CONFIG_MEMCG is enabled, disable cache merging for
912 * KMALLOC_NORMAL caches.
913 */
914 if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_NORMAL))
915 flags |= SLAB_NO_MERGE;
916
917 if (minalign > ARCH_KMALLOC_MINALIGN) {
918 aligned_size = ALIGN(aligned_size, minalign);
919 aligned_idx = __kmalloc_index(aligned_size, false);
920 }
921
922 if (!kmalloc_caches[type][aligned_idx])
923 kmalloc_caches[type][aligned_idx] = create_kmalloc_cache(
924 kmalloc_info[aligned_idx].name[type],
925 aligned_size, flags);
926 if (idx != aligned_idx)
927 kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx];
928 }
929
930 /*
931 * Create the kmalloc array. Some of the regular kmalloc arrays
932 * may already have been created because they were needed to
933 * enable allocations for slab creation.
934 */
create_kmalloc_caches(void)935 void __init create_kmalloc_caches(void)
936 {
937 int i;
938 enum kmalloc_cache_type type;
939
940 /*
941 * Including KMALLOC_CGROUP if CONFIG_MEMCG defined
942 */
943 for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) {
944 /* Caches that are NOT of the two-to-the-power-of size. */
945 if (KMALLOC_MIN_SIZE <= 32)
946 new_kmalloc_cache(1, type);
947 if (KMALLOC_MIN_SIZE <= 64)
948 new_kmalloc_cache(2, type);
949
950 /* Caches that are of the two-to-the-power-of size. */
951 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
952 new_kmalloc_cache(i, type);
953 }
954 #ifdef CONFIG_RANDOM_KMALLOC_CACHES
955 random_kmalloc_seed = get_random_u64();
956 #endif
957
958 /* Kmalloc array is now usable */
959 slab_state = UP;
960
961 if (IS_ENABLED(CONFIG_SLAB_BUCKETS))
962 kmem_buckets_cache = kmem_cache_create("kmalloc_buckets",
963 sizeof(kmem_buckets),
964 0, SLAB_NO_MERGE, NULL);
965 }
966
967 /**
968 * __ksize -- Report full size of underlying allocation
969 * @object: pointer to the object
970 *
971 * This should only be used internally to query the true size of allocations.
972 * It is not meant to be a way to discover the usable size of an allocation
973 * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond
974 * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS,
975 * and/or FORTIFY_SOURCE.
976 *
977 * Return: size of the actual memory used by @object in bytes
978 */
__ksize(const void * object)979 size_t __ksize(const void *object)
980 {
981 struct folio *folio;
982
983 if (unlikely(object == ZERO_SIZE_PTR))
984 return 0;
985
986 folio = virt_to_folio(object);
987
988 if (unlikely(!folio_test_slab(folio))) {
989 if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE))
990 return 0;
991 if (WARN_ON(object != folio_address(folio)))
992 return 0;
993 return folio_size(folio);
994 }
995
996 #ifdef CONFIG_SLUB_DEBUG
997 skip_orig_size_check(folio_slab(folio)->slab_cache, object);
998 #endif
999
1000 return slab_ksize(folio_slab(folio)->slab_cache);
1001 }
1002
kmalloc_fix_flags(gfp_t flags)1003 gfp_t kmalloc_fix_flags(gfp_t flags)
1004 {
1005 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
1006
1007 flags &= ~GFP_SLAB_BUG_MASK;
1008 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
1009 invalid_mask, &invalid_mask, flags, &flags);
1010 dump_stack();
1011
1012 return flags;
1013 }
1014
1015 #ifdef CONFIG_SLAB_FREELIST_RANDOM
1016 /* Randomize a generic freelist */
freelist_randomize(unsigned int * list,unsigned int count)1017 static void freelist_randomize(unsigned int *list,
1018 unsigned int count)
1019 {
1020 unsigned int rand;
1021 unsigned int i;
1022
1023 for (i = 0; i < count; i++)
1024 list[i] = i;
1025
1026 /* Fisher-Yates shuffle */
1027 for (i = count - 1; i > 0; i--) {
1028 rand = get_random_u32_below(i + 1);
1029 swap(list[i], list[rand]);
1030 }
1031 }
1032
1033 /* Create a random sequence per cache */
cache_random_seq_create(struct kmem_cache * cachep,unsigned int count,gfp_t gfp)1034 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
1035 gfp_t gfp)
1036 {
1037
1038 if (count < 2 || cachep->random_seq)
1039 return 0;
1040
1041 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
1042 if (!cachep->random_seq)
1043 return -ENOMEM;
1044
1045 freelist_randomize(cachep->random_seq, count);
1046 return 0;
1047 }
1048
1049 /* Destroy the per-cache random freelist sequence */
cache_random_seq_destroy(struct kmem_cache * cachep)1050 void cache_random_seq_destroy(struct kmem_cache *cachep)
1051 {
1052 kfree(cachep->random_seq);
1053 cachep->random_seq = NULL;
1054 }
1055 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
1056
1057 #ifdef CONFIG_SLUB_DEBUG
1058 #define SLABINFO_RIGHTS (0400)
1059
print_slabinfo_header(struct seq_file * m)1060 static void print_slabinfo_header(struct seq_file *m)
1061 {
1062 /*
1063 * Output format version, so at least we can change it
1064 * without _too_ many complaints.
1065 */
1066 seq_puts(m, "slabinfo - version: 2.1\n");
1067 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
1068 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
1069 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
1070 seq_putc(m, '\n');
1071 }
1072
slab_start(struct seq_file * m,loff_t * pos)1073 static void *slab_start(struct seq_file *m, loff_t *pos)
1074 {
1075 mutex_lock(&slab_mutex);
1076 return seq_list_start(&slab_caches, *pos);
1077 }
1078
slab_next(struct seq_file * m,void * p,loff_t * pos)1079 static void *slab_next(struct seq_file *m, void *p, loff_t *pos)
1080 {
1081 return seq_list_next(p, &slab_caches, pos);
1082 }
1083
slab_stop(struct seq_file * m,void * p)1084 static void slab_stop(struct seq_file *m, void *p)
1085 {
1086 mutex_unlock(&slab_mutex);
1087 }
1088
cache_show(struct kmem_cache * s,struct seq_file * m)1089 static void cache_show(struct kmem_cache *s, struct seq_file *m)
1090 {
1091 struct slabinfo sinfo;
1092
1093 memset(&sinfo, 0, sizeof(sinfo));
1094 get_slabinfo(s, &sinfo);
1095
1096 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
1097 s->name, sinfo.active_objs, sinfo.num_objs, s->size,
1098 sinfo.objects_per_slab, (1 << sinfo.cache_order));
1099
1100 seq_printf(m, " : tunables %4u %4u %4u",
1101 sinfo.limit, sinfo.batchcount, sinfo.shared);
1102 seq_printf(m, " : slabdata %6lu %6lu %6lu",
1103 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
1104 seq_putc(m, '\n');
1105 }
1106
slab_show(struct seq_file * m,void * p)1107 static int slab_show(struct seq_file *m, void *p)
1108 {
1109 struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
1110
1111 if (p == slab_caches.next)
1112 print_slabinfo_header(m);
1113 cache_show(s, m);
1114 return 0;
1115 }
1116
dump_unreclaimable_slab(void)1117 void dump_unreclaimable_slab(void)
1118 {
1119 struct kmem_cache *s;
1120 struct slabinfo sinfo;
1121
1122 /*
1123 * Here acquiring slab_mutex is risky since we don't prefer to get
1124 * sleep in oom path. But, without mutex hold, it may introduce a
1125 * risk of crash.
1126 * Use mutex_trylock to protect the list traverse, dump nothing
1127 * without acquiring the mutex.
1128 */
1129 if (!mutex_trylock(&slab_mutex)) {
1130 pr_warn("excessive unreclaimable slab but cannot dump stats\n");
1131 return;
1132 }
1133
1134 pr_info("Unreclaimable slab info:\n");
1135 pr_info("Name Used Total\n");
1136
1137 list_for_each_entry(s, &slab_caches, list) {
1138 if (s->flags & SLAB_RECLAIM_ACCOUNT)
1139 continue;
1140
1141 get_slabinfo(s, &sinfo);
1142
1143 if (sinfo.num_objs > 0)
1144 pr_info("%-17s %10luKB %10luKB\n", s->name,
1145 (sinfo.active_objs * s->size) / 1024,
1146 (sinfo.num_objs * s->size) / 1024);
1147 }
1148 mutex_unlock(&slab_mutex);
1149 }
1150
1151 /*
1152 * slabinfo_op - iterator that generates /proc/slabinfo
1153 *
1154 * Output layout:
1155 * cache-name
1156 * num-active-objs
1157 * total-objs
1158 * object size
1159 * num-active-slabs
1160 * total-slabs
1161 * num-pages-per-slab
1162 * + further values on SMP and with statistics enabled
1163 */
1164 static const struct seq_operations slabinfo_op = {
1165 .start = slab_start,
1166 .next = slab_next,
1167 .stop = slab_stop,
1168 .show = slab_show,
1169 };
1170
slabinfo_open(struct inode * inode,struct file * file)1171 static int slabinfo_open(struct inode *inode, struct file *file)
1172 {
1173 return seq_open(file, &slabinfo_op);
1174 }
1175
1176 static const struct proc_ops slabinfo_proc_ops = {
1177 .proc_flags = PROC_ENTRY_PERMANENT,
1178 .proc_open = slabinfo_open,
1179 .proc_read = seq_read,
1180 .proc_lseek = seq_lseek,
1181 .proc_release = seq_release,
1182 };
1183
slab_proc_init(void)1184 static int __init slab_proc_init(void)
1185 {
1186 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops);
1187 return 0;
1188 }
1189 module_init(slab_proc_init);
1190
1191 #endif /* CONFIG_SLUB_DEBUG */
1192
1193 static __always_inline __realloc_size(2) void *
__do_krealloc(const void * p,size_t new_size,gfp_t flags)1194 __do_krealloc(const void *p, size_t new_size, gfp_t flags)
1195 {
1196 void *ret;
1197 size_t ks;
1198
1199 /* Check for double-free before calling ksize. */
1200 if (likely(!ZERO_OR_NULL_PTR(p))) {
1201 if (!kasan_check_byte(p))
1202 return NULL;
1203 ks = ksize(p);
1204 } else
1205 ks = 0;
1206
1207 /* If the object still fits, repoison it precisely. */
1208 if (ks >= new_size) {
1209 /* Zero out spare memory. */
1210 if (want_init_on_alloc(flags)) {
1211 kasan_disable_current();
1212 memset(kasan_reset_tag(p) + new_size, 0, ks - new_size);
1213 kasan_enable_current();
1214 }
1215
1216 p = kasan_krealloc((void *)p, new_size, flags);
1217 return (void *)p;
1218 }
1219
1220 ret = kmalloc_node_track_caller_noprof(new_size, flags, NUMA_NO_NODE, _RET_IP_);
1221 if (ret && p) {
1222 /* Disable KASAN checks as the object's redzone is accessed. */
1223 kasan_disable_current();
1224 memcpy(ret, kasan_reset_tag(p), ks);
1225 kasan_enable_current();
1226 }
1227
1228 return ret;
1229 }
1230
1231 /**
1232 * krealloc - reallocate memory. The contents will remain unchanged.
1233 * @p: object to reallocate memory for.
1234 * @new_size: how many bytes of memory are required.
1235 * @flags: the type of memory to allocate.
1236 *
1237 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size
1238 * is 0 and @p is not a %NULL pointer, the object pointed to is freed.
1239 *
1240 * If __GFP_ZERO logic is requested, callers must ensure that, starting with the
1241 * initial memory allocation, every subsequent call to this API for the same
1242 * memory allocation is flagged with __GFP_ZERO. Otherwise, it is possible that
1243 * __GFP_ZERO is not fully honored by this API.
1244 *
1245 * This is the case, since krealloc() only knows about the bucket size of an
1246 * allocation (but not the exact size it was allocated with) and hence
1247 * implements the following semantics for shrinking and growing buffers with
1248 * __GFP_ZERO.
1249 *
1250 * new bucket
1251 * 0 size size
1252 * |--------|----------------|
1253 * | keep | zero |
1254 *
1255 * In any case, the contents of the object pointed to are preserved up to the
1256 * lesser of the new and old sizes.
1257 *
1258 * Return: pointer to the allocated memory or %NULL in case of error
1259 */
krealloc_noprof(const void * p,size_t new_size,gfp_t flags)1260 void *krealloc_noprof(const void *p, size_t new_size, gfp_t flags)
1261 {
1262 void *ret;
1263
1264 if (unlikely(!new_size)) {
1265 kfree(p);
1266 return ZERO_SIZE_PTR;
1267 }
1268
1269 ret = __do_krealloc(p, new_size, flags);
1270 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret))
1271 kfree(p);
1272
1273 return ret;
1274 }
1275 EXPORT_SYMBOL(krealloc_noprof);
1276
1277 /**
1278 * kfree_sensitive - Clear sensitive information in memory before freeing
1279 * @p: object to free memory of
1280 *
1281 * The memory of the object @p points to is zeroed before freed.
1282 * If @p is %NULL, kfree_sensitive() does nothing.
1283 *
1284 * Note: this function zeroes the whole allocated buffer which can be a good
1285 * deal bigger than the requested buffer size passed to kmalloc(). So be
1286 * careful when using this function in performance sensitive code.
1287 */
kfree_sensitive(const void * p)1288 void kfree_sensitive(const void *p)
1289 {
1290 size_t ks;
1291 void *mem = (void *)p;
1292
1293 ks = ksize(mem);
1294 if (ks) {
1295 kasan_unpoison_range(mem, ks);
1296 memzero_explicit(mem, ks);
1297 }
1298 kfree(mem);
1299 }
1300 EXPORT_SYMBOL(kfree_sensitive);
1301
ksize(const void * objp)1302 size_t ksize(const void *objp)
1303 {
1304 /*
1305 * We need to first check that the pointer to the object is valid.
1306 * The KASAN report printed from ksize() is more useful, then when
1307 * it's printed later when the behaviour could be undefined due to
1308 * a potential use-after-free or double-free.
1309 *
1310 * We use kasan_check_byte(), which is supported for the hardware
1311 * tag-based KASAN mode, unlike kasan_check_read/write().
1312 *
1313 * If the pointed to memory is invalid, we return 0 to avoid users of
1314 * ksize() writing to and potentially corrupting the memory region.
1315 *
1316 * We want to perform the check before __ksize(), to avoid potentially
1317 * crashing in __ksize() due to accessing invalid metadata.
1318 */
1319 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp))
1320 return 0;
1321
1322 return kfence_ksize(objp) ?: __ksize(objp);
1323 }
1324 EXPORT_SYMBOL(ksize);
1325
1326 /* Tracepoints definitions. */
1327 EXPORT_TRACEPOINT_SYMBOL(kmalloc);
1328 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
1329 EXPORT_TRACEPOINT_SYMBOL(kfree);
1330 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
1331
1332