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 static LIST_HEAD(slab_caches_to_rcu_destroy); 44 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work); 45 static DECLARE_WORK(slab_caches_to_rcu_destroy_work, 46 slab_caches_to_rcu_destroy_workfn); 47 48 /* 49 * Set of flags that will prevent slab merging 50 */ 51 #define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \ 52 SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \ 53 SLAB_FAILSLAB | SLAB_NO_MERGE) 54 55 #define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \ 56 SLAB_CACHE_DMA32 | SLAB_ACCOUNT) 57 58 /* 59 * Merge control. If this is set then no merging of slab caches will occur. 60 */ 61 static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT); 62 63 static int __init setup_slab_nomerge(char *str) 64 { 65 slab_nomerge = true; 66 return 1; 67 } 68 69 static int __init setup_slab_merge(char *str) 70 { 71 slab_nomerge = false; 72 return 1; 73 } 74 75 __setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0); 76 __setup_param("slub_merge", slub_merge, setup_slab_merge, 0); 77 78 __setup("slab_nomerge", setup_slab_nomerge); 79 __setup("slab_merge", setup_slab_merge); 80 81 /* 82 * Determine the size of a slab object 83 */ 84 unsigned int kmem_cache_size(struct kmem_cache *s) 85 { 86 return s->object_size; 87 } 88 EXPORT_SYMBOL(kmem_cache_size); 89 90 #ifdef CONFIG_DEBUG_VM 91 static int kmem_cache_sanity_check(const char *name, unsigned int size) 92 { 93 if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) { 94 pr_err("kmem_cache_create(%s) integrity check failed\n", name); 95 return -EINVAL; 96 } 97 98 WARN_ON(strchr(name, ' ')); /* It confuses parsers */ 99 return 0; 100 } 101 #else 102 static inline int kmem_cache_sanity_check(const char *name, unsigned int size) 103 { 104 return 0; 105 } 106 #endif 107 108 /* 109 * Figure out what the alignment of the objects will be given a set of 110 * flags, a user specified alignment and the size of the objects. 111 */ 112 static unsigned int calculate_alignment(slab_flags_t flags, 113 unsigned int align, unsigned int size) 114 { 115 /* 116 * If the user wants hardware cache aligned objects then follow that 117 * suggestion if the object is sufficiently large. 118 * 119 * The hardware cache alignment cannot override the specified 120 * alignment though. If that is greater then use it. 121 */ 122 if (flags & SLAB_HWCACHE_ALIGN) { 123 unsigned int ralign; 124 125 ralign = cache_line_size(); 126 while (size <= ralign / 2) 127 ralign /= 2; 128 align = max(align, ralign); 129 } 130 131 align = max(align, arch_slab_minalign()); 132 133 return ALIGN(align, sizeof(void *)); 134 } 135 136 /* 137 * Find a mergeable slab cache 138 */ 139 int slab_unmergeable(struct kmem_cache *s) 140 { 141 if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE)) 142 return 1; 143 144 if (s->ctor) 145 return 1; 146 147 #ifdef CONFIG_HARDENED_USERCOPY 148 if (s->usersize) 149 return 1; 150 #endif 151 152 /* 153 * We may have set a slab to be unmergeable during bootstrap. 154 */ 155 if (s->refcount < 0) 156 return 1; 157 158 return 0; 159 } 160 161 struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 162 slab_flags_t flags, const char *name, void (*ctor)(void *)) 163 { 164 struct kmem_cache *s; 165 166 if (slab_nomerge) 167 return NULL; 168 169 if (ctor) 170 return NULL; 171 172 size = ALIGN(size, sizeof(void *)); 173 align = calculate_alignment(flags, align, size); 174 size = ALIGN(size, align); 175 flags = kmem_cache_flags(flags, name); 176 177 if (flags & SLAB_NEVER_MERGE) 178 return NULL; 179 180 list_for_each_entry_reverse(s, &slab_caches, list) { 181 if (slab_unmergeable(s)) 182 continue; 183 184 if (size > s->size) 185 continue; 186 187 if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME)) 188 continue; 189 /* 190 * Check if alignment is compatible. 191 * Courtesy of Adrian Drzewiecki 192 */ 193 if ((s->size & ~(align - 1)) != s->size) 194 continue; 195 196 if (s->size - size >= sizeof(void *)) 197 continue; 198 199 return s; 200 } 201 return NULL; 202 } 203 204 static struct kmem_cache *create_cache(const char *name, 205 unsigned int object_size, unsigned int align, 206 slab_flags_t flags, unsigned int useroffset, 207 unsigned int usersize, void (*ctor)(void *), 208 struct kmem_cache *root_cache) 209 { 210 struct kmem_cache *s; 211 int err; 212 213 if (WARN_ON(useroffset + usersize > object_size)) 214 useroffset = usersize = 0; 215 216 err = -ENOMEM; 217 s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); 218 if (!s) 219 goto out; 220 221 s->name = name; 222 s->size = s->object_size = object_size; 223 s->align = align; 224 s->ctor = ctor; 225 #ifdef CONFIG_HARDENED_USERCOPY 226 s->useroffset = useroffset; 227 s->usersize = usersize; 228 #endif 229 230 err = __kmem_cache_create(s, flags); 231 if (err) 232 goto out_free_cache; 233 234 s->refcount = 1; 235 list_add(&s->list, &slab_caches); 236 return s; 237 238 out_free_cache: 239 kmem_cache_free(kmem_cache, s); 240 out: 241 return ERR_PTR(err); 242 } 243 244 /** 245 * kmem_cache_create_usercopy - Create a cache with a region suitable 246 * for copying to userspace 247 * @name: A string which is used in /proc/slabinfo to identify this cache. 248 * @size: The size of objects to be created in this cache. 249 * @align: The required alignment for the objects. 250 * @flags: SLAB flags 251 * @useroffset: Usercopy region offset 252 * @usersize: Usercopy region size 253 * @ctor: A constructor for the objects. 254 * 255 * Cannot be called within a interrupt, but can be interrupted. 256 * The @ctor is run when new pages are allocated by the cache. 257 * 258 * The flags are 259 * 260 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 261 * to catch references to uninitialised memory. 262 * 263 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 264 * for buffer overruns. 265 * 266 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 267 * cacheline. This can be beneficial if you're counting cycles as closely 268 * as davem. 269 * 270 * Return: a pointer to the cache on success, NULL on failure. 271 */ 272 struct kmem_cache * 273 kmem_cache_create_usercopy(const char *name, 274 unsigned int size, unsigned int align, 275 slab_flags_t flags, 276 unsigned int useroffset, unsigned int usersize, 277 void (*ctor)(void *)) 278 { 279 struct kmem_cache *s = NULL; 280 const char *cache_name; 281 int err; 282 283 #ifdef CONFIG_SLUB_DEBUG 284 /* 285 * If no slab_debug was enabled globally, the static key is not yet 286 * enabled by setup_slub_debug(). Enable it if the cache is being 287 * created with any of the debugging flags passed explicitly. 288 * It's also possible that this is the first cache created with 289 * SLAB_STORE_USER and we should init stack_depot for it. 290 */ 291 if (flags & SLAB_DEBUG_FLAGS) 292 static_branch_enable(&slub_debug_enabled); 293 if (flags & SLAB_STORE_USER) 294 stack_depot_init(); 295 #endif 296 297 mutex_lock(&slab_mutex); 298 299 err = kmem_cache_sanity_check(name, size); 300 if (err) { 301 goto out_unlock; 302 } 303 304 /* Refuse requests with allocator specific flags */ 305 if (flags & ~SLAB_FLAGS_PERMITTED) { 306 err = -EINVAL; 307 goto out_unlock; 308 } 309 310 /* 311 * Some allocators will constraint the set of valid flags to a subset 312 * of all flags. We expect them to define CACHE_CREATE_MASK in this 313 * case, and we'll just provide them with a sanitized version of the 314 * passed flags. 315 */ 316 flags &= CACHE_CREATE_MASK; 317 318 /* Fail closed on bad usersize of useroffset values. */ 319 if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) || 320 WARN_ON(!usersize && useroffset) || 321 WARN_ON(size < usersize || size - usersize < useroffset)) 322 usersize = useroffset = 0; 323 324 if (!usersize) 325 s = __kmem_cache_alias(name, size, align, flags, ctor); 326 if (s) 327 goto out_unlock; 328 329 cache_name = kstrdup_const(name, GFP_KERNEL); 330 if (!cache_name) { 331 err = -ENOMEM; 332 goto out_unlock; 333 } 334 335 s = create_cache(cache_name, size, 336 calculate_alignment(flags, align, size), 337 flags, useroffset, usersize, ctor, NULL); 338 if (IS_ERR(s)) { 339 err = PTR_ERR(s); 340 kfree_const(cache_name); 341 } 342 343 out_unlock: 344 mutex_unlock(&slab_mutex); 345 346 if (err) { 347 if (flags & SLAB_PANIC) 348 panic("%s: Failed to create slab '%s'. Error %d\n", 349 __func__, name, err); 350 else { 351 pr_warn("%s(%s) failed with error %d\n", 352 __func__, name, err); 353 dump_stack(); 354 } 355 return NULL; 356 } 357 return s; 358 } 359 EXPORT_SYMBOL(kmem_cache_create_usercopy); 360 361 /** 362 * kmem_cache_create - Create a cache. 363 * @name: A string which is used in /proc/slabinfo to identify this cache. 364 * @size: The size of objects to be created in this cache. 365 * @align: The required alignment for the objects. 366 * @flags: SLAB flags 367 * @ctor: A constructor for the objects. 368 * 369 * Cannot be called within a interrupt, but can be interrupted. 370 * The @ctor is run when new pages are allocated by the cache. 371 * 372 * The flags are 373 * 374 * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) 375 * to catch references to uninitialised memory. 376 * 377 * %SLAB_RED_ZONE - Insert `Red` zones around the allocated memory to check 378 * for buffer overruns. 379 * 380 * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware 381 * cacheline. This can be beneficial if you're counting cycles as closely 382 * as davem. 383 * 384 * Return: a pointer to the cache on success, NULL on failure. 385 */ 386 struct kmem_cache * 387 kmem_cache_create(const char *name, unsigned int size, unsigned int align, 388 slab_flags_t flags, void (*ctor)(void *)) 389 { 390 return kmem_cache_create_usercopy(name, size, align, flags, 0, 0, 391 ctor); 392 } 393 EXPORT_SYMBOL(kmem_cache_create); 394 395 static struct kmem_cache *kmem_buckets_cache __ro_after_init; 396 397 /** 398 * kmem_buckets_create - Create a set of caches that handle dynamic sized 399 * allocations via kmem_buckets_alloc() 400 * @name: A prefix string which is used in /proc/slabinfo to identify this 401 * cache. The individual caches with have their sizes as the suffix. 402 * @flags: SLAB flags (see kmem_cache_create() for details). 403 * @useroffset: Starting offset within an allocation that may be copied 404 * to/from userspace. 405 * @usersize: How many bytes, starting at @useroffset, may be copied 406 * to/from userspace. 407 * @ctor: A constructor for the objects, run when new allocations are made. 408 * 409 * Cannot be called within an interrupt, but can be interrupted. 410 * 411 * Return: a pointer to the cache on success, NULL on failure. When 412 * CONFIG_SLAB_BUCKETS is not enabled, ZERO_SIZE_PTR is returned, and 413 * subsequent calls to kmem_buckets_alloc() will fall back to kmalloc(). 414 * (i.e. callers only need to check for NULL on failure.) 415 */ 416 kmem_buckets *kmem_buckets_create(const char *name, slab_flags_t flags, 417 unsigned int useroffset, 418 unsigned int usersize, 419 void (*ctor)(void *)) 420 { 421 kmem_buckets *b; 422 int idx; 423 424 /* 425 * When the separate buckets API is not built in, just return 426 * a non-NULL value for the kmem_buckets pointer, which will be 427 * unused when performing allocations. 428 */ 429 if (!IS_ENABLED(CONFIG_SLAB_BUCKETS)) 430 return ZERO_SIZE_PTR; 431 432 if (WARN_ON(!kmem_buckets_cache)) 433 return NULL; 434 435 b = kmem_cache_alloc(kmem_buckets_cache, GFP_KERNEL|__GFP_ZERO); 436 if (WARN_ON(!b)) 437 return NULL; 438 439 flags |= SLAB_NO_MERGE; 440 441 for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) { 442 char *short_size, *cache_name; 443 unsigned int cache_useroffset, cache_usersize; 444 unsigned int size; 445 446 if (!kmalloc_caches[KMALLOC_NORMAL][idx]) 447 continue; 448 449 size = kmalloc_caches[KMALLOC_NORMAL][idx]->object_size; 450 if (!size) 451 continue; 452 453 short_size = strchr(kmalloc_caches[KMALLOC_NORMAL][idx]->name, '-'); 454 if (WARN_ON(!short_size)) 455 goto fail; 456 457 cache_name = kasprintf(GFP_KERNEL, "%s-%s", name, short_size + 1); 458 if (WARN_ON(!cache_name)) 459 goto fail; 460 461 if (useroffset >= size) { 462 cache_useroffset = 0; 463 cache_usersize = 0; 464 } else { 465 cache_useroffset = useroffset; 466 cache_usersize = min(size - cache_useroffset, usersize); 467 } 468 (*b)[idx] = kmem_cache_create_usercopy(cache_name, size, 469 0, flags, cache_useroffset, 470 cache_usersize, ctor); 471 kfree(cache_name); 472 if (WARN_ON(!(*b)[idx])) 473 goto fail; 474 } 475 476 return b; 477 478 fail: 479 for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) 480 kmem_cache_destroy((*b)[idx]); 481 kfree(b); 482 483 return NULL; 484 } 485 EXPORT_SYMBOL(kmem_buckets_create); 486 487 #ifdef SLAB_SUPPORTS_SYSFS 488 /* 489 * For a given kmem_cache, kmem_cache_destroy() should only be called 490 * once or there will be a use-after-free problem. The actual deletion 491 * and release of the kobject does not need slab_mutex or cpu_hotplug_lock 492 * protection. So they are now done without holding those locks. 493 * 494 * Note that there will be a slight delay in the deletion of sysfs files 495 * if kmem_cache_release() is called indrectly from a work function. 496 */ 497 static void kmem_cache_release(struct kmem_cache *s) 498 { 499 if (slab_state >= FULL) { 500 sysfs_slab_unlink(s); 501 sysfs_slab_release(s); 502 } else { 503 slab_kmem_cache_release(s); 504 } 505 } 506 #else 507 static void kmem_cache_release(struct kmem_cache *s) 508 { 509 slab_kmem_cache_release(s); 510 } 511 #endif 512 513 static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work) 514 { 515 LIST_HEAD(to_destroy); 516 struct kmem_cache *s, *s2; 517 518 /* 519 * On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the 520 * @slab_caches_to_rcu_destroy list. The slab pages are freed 521 * through RCU and the associated kmem_cache are dereferenced 522 * while freeing the pages, so the kmem_caches should be freed only 523 * after the pending RCU operations are finished. As rcu_barrier() 524 * is a pretty slow operation, we batch all pending destructions 525 * asynchronously. 526 */ 527 mutex_lock(&slab_mutex); 528 list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy); 529 mutex_unlock(&slab_mutex); 530 531 if (list_empty(&to_destroy)) 532 return; 533 534 rcu_barrier(); 535 536 list_for_each_entry_safe(s, s2, &to_destroy, list) { 537 debugfs_slab_release(s); 538 kfence_shutdown_cache(s); 539 kmem_cache_release(s); 540 } 541 } 542 543 static int shutdown_cache(struct kmem_cache *s) 544 { 545 /* free asan quarantined objects */ 546 kasan_cache_shutdown(s); 547 548 if (__kmem_cache_shutdown(s) != 0) 549 return -EBUSY; 550 551 list_del(&s->list); 552 553 if (s->flags & SLAB_TYPESAFE_BY_RCU) { 554 list_add_tail(&s->list, &slab_caches_to_rcu_destroy); 555 schedule_work(&slab_caches_to_rcu_destroy_work); 556 } else { 557 kfence_shutdown_cache(s); 558 debugfs_slab_release(s); 559 } 560 561 return 0; 562 } 563 564 void slab_kmem_cache_release(struct kmem_cache *s) 565 { 566 __kmem_cache_release(s); 567 kfree_const(s->name); 568 kmem_cache_free(kmem_cache, s); 569 } 570 571 void kmem_cache_destroy(struct kmem_cache *s) 572 { 573 int err = -EBUSY; 574 bool rcu_set; 575 576 if (unlikely(!s) || !kasan_check_byte(s)) 577 return; 578 579 cpus_read_lock(); 580 mutex_lock(&slab_mutex); 581 582 rcu_set = s->flags & SLAB_TYPESAFE_BY_RCU; 583 584 s->refcount--; 585 if (s->refcount) 586 goto out_unlock; 587 588 err = shutdown_cache(s); 589 WARN(err, "%s %s: Slab cache still has objects when called from %pS", 590 __func__, s->name, (void *)_RET_IP_); 591 out_unlock: 592 mutex_unlock(&slab_mutex); 593 cpus_read_unlock(); 594 if (!err && !rcu_set) 595 kmem_cache_release(s); 596 } 597 EXPORT_SYMBOL(kmem_cache_destroy); 598 599 /** 600 * kmem_cache_shrink - Shrink a cache. 601 * @cachep: The cache to shrink. 602 * 603 * Releases as many slabs as possible for a cache. 604 * To help debugging, a zero exit status indicates all slabs were released. 605 * 606 * Return: %0 if all slabs were released, non-zero otherwise 607 */ 608 int kmem_cache_shrink(struct kmem_cache *cachep) 609 { 610 kasan_cache_shrink(cachep); 611 612 return __kmem_cache_shrink(cachep); 613 } 614 EXPORT_SYMBOL(kmem_cache_shrink); 615 616 bool slab_is_available(void) 617 { 618 return slab_state >= UP; 619 } 620 621 #ifdef CONFIG_PRINTK 622 static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) 623 { 624 if (__kfence_obj_info(kpp, object, slab)) 625 return; 626 __kmem_obj_info(kpp, object, slab); 627 } 628 629 /** 630 * kmem_dump_obj - Print available slab provenance information 631 * @object: slab object for which to find provenance information. 632 * 633 * This function uses pr_cont(), so that the caller is expected to have 634 * printed out whatever preamble is appropriate. The provenance information 635 * depends on the type of object and on how much debugging is enabled. 636 * For a slab-cache object, the fact that it is a slab object is printed, 637 * and, if available, the slab name, return address, and stack trace from 638 * the allocation and last free path of that object. 639 * 640 * Return: %true if the pointer is to a not-yet-freed object from 641 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer 642 * is to an already-freed object, and %false otherwise. 643 */ 644 bool kmem_dump_obj(void *object) 645 { 646 char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc"; 647 int i; 648 struct slab *slab; 649 unsigned long ptroffset; 650 struct kmem_obj_info kp = { }; 651 652 /* Some arches consider ZERO_SIZE_PTR to be a valid address. */ 653 if (object < (void *)PAGE_SIZE || !virt_addr_valid(object)) 654 return false; 655 slab = virt_to_slab(object); 656 if (!slab) 657 return false; 658 659 kmem_obj_info(&kp, object, slab); 660 if (kp.kp_slab_cache) 661 pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name); 662 else 663 pr_cont(" slab%s", cp); 664 if (is_kfence_address(object)) 665 pr_cont(" (kfence)"); 666 if (kp.kp_objp) 667 pr_cont(" start %px", kp.kp_objp); 668 if (kp.kp_data_offset) 669 pr_cont(" data offset %lu", kp.kp_data_offset); 670 if (kp.kp_objp) { 671 ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset; 672 pr_cont(" pointer offset %lu", ptroffset); 673 } 674 if (kp.kp_slab_cache && kp.kp_slab_cache->object_size) 675 pr_cont(" size %u", kp.kp_slab_cache->object_size); 676 if (kp.kp_ret) 677 pr_cont(" allocated at %pS\n", kp.kp_ret); 678 else 679 pr_cont("\n"); 680 for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) { 681 if (!kp.kp_stack[i]) 682 break; 683 pr_info(" %pS\n", kp.kp_stack[i]); 684 } 685 686 if (kp.kp_free_stack[0]) 687 pr_cont(" Free path:\n"); 688 689 for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) { 690 if (!kp.kp_free_stack[i]) 691 break; 692 pr_info(" %pS\n", kp.kp_free_stack[i]); 693 } 694 695 return true; 696 } 697 EXPORT_SYMBOL_GPL(kmem_dump_obj); 698 #endif 699 700 /* Create a cache during boot when no slab services are available yet */ 701 void __init create_boot_cache(struct kmem_cache *s, const char *name, 702 unsigned int size, slab_flags_t flags, 703 unsigned int useroffset, unsigned int usersize) 704 { 705 int err; 706 unsigned int align = ARCH_KMALLOC_MINALIGN; 707 708 s->name = name; 709 s->size = s->object_size = size; 710 711 /* 712 * kmalloc caches guarantee alignment of at least the largest 713 * power-of-two divisor of the size. For power-of-two sizes, 714 * it is the size itself. 715 */ 716 if (flags & SLAB_KMALLOC) 717 align = max(align, 1U << (ffs(size) - 1)); 718 s->align = calculate_alignment(flags, align, size); 719 720 #ifdef CONFIG_HARDENED_USERCOPY 721 s->useroffset = useroffset; 722 s->usersize = usersize; 723 #endif 724 725 err = __kmem_cache_create(s, flags); 726 727 if (err) 728 panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n", 729 name, size, err); 730 731 s->refcount = -1; /* Exempt from merging for now */ 732 } 733 734 static struct kmem_cache *__init create_kmalloc_cache(const char *name, 735 unsigned int size, 736 slab_flags_t flags) 737 { 738 struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); 739 740 if (!s) 741 panic("Out of memory when creating slab %s\n", name); 742 743 create_boot_cache(s, name, size, flags | SLAB_KMALLOC, 0, size); 744 list_add(&s->list, &slab_caches); 745 s->refcount = 1; 746 return s; 747 } 748 749 kmem_buckets kmalloc_caches[NR_KMALLOC_TYPES] __ro_after_init = 750 { /* initialization for https://llvm.org/pr42570 */ }; 751 EXPORT_SYMBOL(kmalloc_caches); 752 753 #ifdef CONFIG_RANDOM_KMALLOC_CACHES 754 unsigned long random_kmalloc_seed __ro_after_init; 755 EXPORT_SYMBOL(random_kmalloc_seed); 756 #endif 757 758 /* 759 * Conversion table for small slabs sizes / 8 to the index in the 760 * kmalloc array. This is necessary for slabs < 192 since we have non power 761 * of two cache sizes there. The size of larger slabs can be determined using 762 * fls. 763 */ 764 u8 kmalloc_size_index[24] __ro_after_init = { 765 3, /* 8 */ 766 4, /* 16 */ 767 5, /* 24 */ 768 5, /* 32 */ 769 6, /* 40 */ 770 6, /* 48 */ 771 6, /* 56 */ 772 6, /* 64 */ 773 1, /* 72 */ 774 1, /* 80 */ 775 1, /* 88 */ 776 1, /* 96 */ 777 7, /* 104 */ 778 7, /* 112 */ 779 7, /* 120 */ 780 7, /* 128 */ 781 2, /* 136 */ 782 2, /* 144 */ 783 2, /* 152 */ 784 2, /* 160 */ 785 2, /* 168 */ 786 2, /* 176 */ 787 2, /* 184 */ 788 2 /* 192 */ 789 }; 790 791 size_t kmalloc_size_roundup(size_t size) 792 { 793 if (size && size <= KMALLOC_MAX_CACHE_SIZE) { 794 /* 795 * The flags don't matter since size_index is common to all. 796 * Neither does the caller for just getting ->object_size. 797 */ 798 return kmalloc_slab(size, NULL, GFP_KERNEL, 0)->object_size; 799 } 800 801 /* Above the smaller buckets, size is a multiple of page size. */ 802 if (size && size <= KMALLOC_MAX_SIZE) 803 return PAGE_SIZE << get_order(size); 804 805 /* 806 * Return 'size' for 0 - kmalloc() returns ZERO_SIZE_PTR 807 * and very large size - kmalloc() may fail. 808 */ 809 return size; 810 811 } 812 EXPORT_SYMBOL(kmalloc_size_roundup); 813 814 #ifdef CONFIG_ZONE_DMA 815 #define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz, 816 #else 817 #define KMALLOC_DMA_NAME(sz) 818 #endif 819 820 #ifdef CONFIG_MEMCG 821 #define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz, 822 #else 823 #define KMALLOC_CGROUP_NAME(sz) 824 #endif 825 826 #ifndef CONFIG_SLUB_TINY 827 #define KMALLOC_RCL_NAME(sz) .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz, 828 #else 829 #define KMALLOC_RCL_NAME(sz) 830 #endif 831 832 #ifdef CONFIG_RANDOM_KMALLOC_CACHES 833 #define __KMALLOC_RANDOM_CONCAT(a, b) a ## b 834 #define KMALLOC_RANDOM_NAME(N, sz) __KMALLOC_RANDOM_CONCAT(KMA_RAND_, N)(sz) 835 #define KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 1] = "kmalloc-rnd-01-" #sz, 836 #define KMA_RAND_2(sz) KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 2] = "kmalloc-rnd-02-" #sz, 837 #define KMA_RAND_3(sz) KMA_RAND_2(sz) .name[KMALLOC_RANDOM_START + 3] = "kmalloc-rnd-03-" #sz, 838 #define KMA_RAND_4(sz) KMA_RAND_3(sz) .name[KMALLOC_RANDOM_START + 4] = "kmalloc-rnd-04-" #sz, 839 #define KMA_RAND_5(sz) KMA_RAND_4(sz) .name[KMALLOC_RANDOM_START + 5] = "kmalloc-rnd-05-" #sz, 840 #define KMA_RAND_6(sz) KMA_RAND_5(sz) .name[KMALLOC_RANDOM_START + 6] = "kmalloc-rnd-06-" #sz, 841 #define KMA_RAND_7(sz) KMA_RAND_6(sz) .name[KMALLOC_RANDOM_START + 7] = "kmalloc-rnd-07-" #sz, 842 #define KMA_RAND_8(sz) KMA_RAND_7(sz) .name[KMALLOC_RANDOM_START + 8] = "kmalloc-rnd-08-" #sz, 843 #define KMA_RAND_9(sz) KMA_RAND_8(sz) .name[KMALLOC_RANDOM_START + 9] = "kmalloc-rnd-09-" #sz, 844 #define KMA_RAND_10(sz) KMA_RAND_9(sz) .name[KMALLOC_RANDOM_START + 10] = "kmalloc-rnd-10-" #sz, 845 #define KMA_RAND_11(sz) KMA_RAND_10(sz) .name[KMALLOC_RANDOM_START + 11] = "kmalloc-rnd-11-" #sz, 846 #define KMA_RAND_12(sz) KMA_RAND_11(sz) .name[KMALLOC_RANDOM_START + 12] = "kmalloc-rnd-12-" #sz, 847 #define KMA_RAND_13(sz) KMA_RAND_12(sz) .name[KMALLOC_RANDOM_START + 13] = "kmalloc-rnd-13-" #sz, 848 #define KMA_RAND_14(sz) KMA_RAND_13(sz) .name[KMALLOC_RANDOM_START + 14] = "kmalloc-rnd-14-" #sz, 849 #define KMA_RAND_15(sz) KMA_RAND_14(sz) .name[KMALLOC_RANDOM_START + 15] = "kmalloc-rnd-15-" #sz, 850 #else // CONFIG_RANDOM_KMALLOC_CACHES 851 #define KMALLOC_RANDOM_NAME(N, sz) 852 #endif 853 854 #define INIT_KMALLOC_INFO(__size, __short_size) \ 855 { \ 856 .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \ 857 KMALLOC_RCL_NAME(__short_size) \ 858 KMALLOC_CGROUP_NAME(__short_size) \ 859 KMALLOC_DMA_NAME(__short_size) \ 860 KMALLOC_RANDOM_NAME(RANDOM_KMALLOC_CACHES_NR, __short_size) \ 861 .size = __size, \ 862 } 863 864 /* 865 * kmalloc_info[] is to make slab_debug=,kmalloc-xx option work at boot time. 866 * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is 867 * kmalloc-2M. 868 */ 869 const struct kmalloc_info_struct kmalloc_info[] __initconst = { 870 INIT_KMALLOC_INFO(0, 0), 871 INIT_KMALLOC_INFO(96, 96), 872 INIT_KMALLOC_INFO(192, 192), 873 INIT_KMALLOC_INFO(8, 8), 874 INIT_KMALLOC_INFO(16, 16), 875 INIT_KMALLOC_INFO(32, 32), 876 INIT_KMALLOC_INFO(64, 64), 877 INIT_KMALLOC_INFO(128, 128), 878 INIT_KMALLOC_INFO(256, 256), 879 INIT_KMALLOC_INFO(512, 512), 880 INIT_KMALLOC_INFO(1024, 1k), 881 INIT_KMALLOC_INFO(2048, 2k), 882 INIT_KMALLOC_INFO(4096, 4k), 883 INIT_KMALLOC_INFO(8192, 8k), 884 INIT_KMALLOC_INFO(16384, 16k), 885 INIT_KMALLOC_INFO(32768, 32k), 886 INIT_KMALLOC_INFO(65536, 64k), 887 INIT_KMALLOC_INFO(131072, 128k), 888 INIT_KMALLOC_INFO(262144, 256k), 889 INIT_KMALLOC_INFO(524288, 512k), 890 INIT_KMALLOC_INFO(1048576, 1M), 891 INIT_KMALLOC_INFO(2097152, 2M) 892 }; 893 894 /* 895 * Patch up the size_index table if we have strange large alignment 896 * requirements for the kmalloc array. This is only the case for 897 * MIPS it seems. The standard arches will not generate any code here. 898 * 899 * Largest permitted alignment is 256 bytes due to the way we 900 * handle the index determination for the smaller caches. 901 * 902 * Make sure that nothing crazy happens if someone starts tinkering 903 * around with ARCH_KMALLOC_MINALIGN 904 */ 905 void __init setup_kmalloc_cache_index_table(void) 906 { 907 unsigned int i; 908 909 BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || 910 !is_power_of_2(KMALLOC_MIN_SIZE)); 911 912 for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { 913 unsigned int elem = size_index_elem(i); 914 915 if (elem >= ARRAY_SIZE(kmalloc_size_index)) 916 break; 917 kmalloc_size_index[elem] = KMALLOC_SHIFT_LOW; 918 } 919 920 if (KMALLOC_MIN_SIZE >= 64) { 921 /* 922 * The 96 byte sized cache is not used if the alignment 923 * is 64 byte. 924 */ 925 for (i = 64 + 8; i <= 96; i += 8) 926 kmalloc_size_index[size_index_elem(i)] = 7; 927 928 } 929 930 if (KMALLOC_MIN_SIZE >= 128) { 931 /* 932 * The 192 byte sized cache is not used if the alignment 933 * is 128 byte. Redirect kmalloc to use the 256 byte cache 934 * instead. 935 */ 936 for (i = 128 + 8; i <= 192; i += 8) 937 kmalloc_size_index[size_index_elem(i)] = 8; 938 } 939 } 940 941 static unsigned int __kmalloc_minalign(void) 942 { 943 unsigned int minalign = dma_get_cache_alignment(); 944 945 if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && 946 is_swiotlb_allocated()) 947 minalign = ARCH_KMALLOC_MINALIGN; 948 949 return max(minalign, arch_slab_minalign()); 950 } 951 952 static void __init 953 new_kmalloc_cache(int idx, enum kmalloc_cache_type type) 954 { 955 slab_flags_t flags = 0; 956 unsigned int minalign = __kmalloc_minalign(); 957 unsigned int aligned_size = kmalloc_info[idx].size; 958 int aligned_idx = idx; 959 960 if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) { 961 flags |= SLAB_RECLAIM_ACCOUNT; 962 } else if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_CGROUP)) { 963 if (mem_cgroup_kmem_disabled()) { 964 kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx]; 965 return; 966 } 967 flags |= SLAB_ACCOUNT; 968 } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) { 969 flags |= SLAB_CACHE_DMA; 970 } 971 972 #ifdef CONFIG_RANDOM_KMALLOC_CACHES 973 if (type >= KMALLOC_RANDOM_START && type <= KMALLOC_RANDOM_END) 974 flags |= SLAB_NO_MERGE; 975 #endif 976 977 /* 978 * If CONFIG_MEMCG is enabled, disable cache merging for 979 * KMALLOC_NORMAL caches. 980 */ 981 if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_NORMAL)) 982 flags |= SLAB_NO_MERGE; 983 984 if (minalign > ARCH_KMALLOC_MINALIGN) { 985 aligned_size = ALIGN(aligned_size, minalign); 986 aligned_idx = __kmalloc_index(aligned_size, false); 987 } 988 989 if (!kmalloc_caches[type][aligned_idx]) 990 kmalloc_caches[type][aligned_idx] = create_kmalloc_cache( 991 kmalloc_info[aligned_idx].name[type], 992 aligned_size, flags); 993 if (idx != aligned_idx) 994 kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx]; 995 } 996 997 /* 998 * Create the kmalloc array. Some of the regular kmalloc arrays 999 * may already have been created because they were needed to 1000 * enable allocations for slab creation. 1001 */ 1002 void __init create_kmalloc_caches(void) 1003 { 1004 int i; 1005 enum kmalloc_cache_type type; 1006 1007 /* 1008 * Including KMALLOC_CGROUP if CONFIG_MEMCG defined 1009 */ 1010 for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) { 1011 /* Caches that are NOT of the two-to-the-power-of size. */ 1012 if (KMALLOC_MIN_SIZE <= 32) 1013 new_kmalloc_cache(1, type); 1014 if (KMALLOC_MIN_SIZE <= 64) 1015 new_kmalloc_cache(2, type); 1016 1017 /* Caches that are of the two-to-the-power-of size. */ 1018 for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) 1019 new_kmalloc_cache(i, type); 1020 } 1021 #ifdef CONFIG_RANDOM_KMALLOC_CACHES 1022 random_kmalloc_seed = get_random_u64(); 1023 #endif 1024 1025 /* Kmalloc array is now usable */ 1026 slab_state = UP; 1027 1028 if (IS_ENABLED(CONFIG_SLAB_BUCKETS)) 1029 kmem_buckets_cache = kmem_cache_create("kmalloc_buckets", 1030 sizeof(kmem_buckets), 1031 0, SLAB_NO_MERGE, NULL); 1032 } 1033 1034 /** 1035 * __ksize -- Report full size of underlying allocation 1036 * @object: pointer to the object 1037 * 1038 * This should only be used internally to query the true size of allocations. 1039 * It is not meant to be a way to discover the usable size of an allocation 1040 * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond 1041 * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS, 1042 * and/or FORTIFY_SOURCE. 1043 * 1044 * Return: size of the actual memory used by @object in bytes 1045 */ 1046 size_t __ksize(const void *object) 1047 { 1048 struct folio *folio; 1049 1050 if (unlikely(object == ZERO_SIZE_PTR)) 1051 return 0; 1052 1053 folio = virt_to_folio(object); 1054 1055 if (unlikely(!folio_test_slab(folio))) { 1056 if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE)) 1057 return 0; 1058 if (WARN_ON(object != folio_address(folio))) 1059 return 0; 1060 return folio_size(folio); 1061 } 1062 1063 #ifdef CONFIG_SLUB_DEBUG 1064 skip_orig_size_check(folio_slab(folio)->slab_cache, object); 1065 #endif 1066 1067 return slab_ksize(folio_slab(folio)->slab_cache); 1068 } 1069 1070 gfp_t kmalloc_fix_flags(gfp_t flags) 1071 { 1072 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; 1073 1074 flags &= ~GFP_SLAB_BUG_MASK; 1075 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", 1076 invalid_mask, &invalid_mask, flags, &flags); 1077 dump_stack(); 1078 1079 return flags; 1080 } 1081 1082 #ifdef CONFIG_SLAB_FREELIST_RANDOM 1083 /* Randomize a generic freelist */ 1084 static void freelist_randomize(unsigned int *list, 1085 unsigned int count) 1086 { 1087 unsigned int rand; 1088 unsigned int i; 1089 1090 for (i = 0; i < count; i++) 1091 list[i] = i; 1092 1093 /* Fisher-Yates shuffle */ 1094 for (i = count - 1; i > 0; i--) { 1095 rand = get_random_u32_below(i + 1); 1096 swap(list[i], list[rand]); 1097 } 1098 } 1099 1100 /* Create a random sequence per cache */ 1101 int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count, 1102 gfp_t gfp) 1103 { 1104 1105 if (count < 2 || cachep->random_seq) 1106 return 0; 1107 1108 cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp); 1109 if (!cachep->random_seq) 1110 return -ENOMEM; 1111 1112 freelist_randomize(cachep->random_seq, count); 1113 return 0; 1114 } 1115 1116 /* Destroy the per-cache random freelist sequence */ 1117 void cache_random_seq_destroy(struct kmem_cache *cachep) 1118 { 1119 kfree(cachep->random_seq); 1120 cachep->random_seq = NULL; 1121 } 1122 #endif /* CONFIG_SLAB_FREELIST_RANDOM */ 1123 1124 #ifdef CONFIG_SLUB_DEBUG 1125 #define SLABINFO_RIGHTS (0400) 1126 1127 static void print_slabinfo_header(struct seq_file *m) 1128 { 1129 /* 1130 * Output format version, so at least we can change it 1131 * without _too_ many complaints. 1132 */ 1133 seq_puts(m, "slabinfo - version: 2.1\n"); 1134 seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); 1135 seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); 1136 seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); 1137 seq_putc(m, '\n'); 1138 } 1139 1140 static void *slab_start(struct seq_file *m, loff_t *pos) 1141 { 1142 mutex_lock(&slab_mutex); 1143 return seq_list_start(&slab_caches, *pos); 1144 } 1145 1146 static void *slab_next(struct seq_file *m, void *p, loff_t *pos) 1147 { 1148 return seq_list_next(p, &slab_caches, pos); 1149 } 1150 1151 static void slab_stop(struct seq_file *m, void *p) 1152 { 1153 mutex_unlock(&slab_mutex); 1154 } 1155 1156 static void cache_show(struct kmem_cache *s, struct seq_file *m) 1157 { 1158 struct slabinfo sinfo; 1159 1160 memset(&sinfo, 0, sizeof(sinfo)); 1161 get_slabinfo(s, &sinfo); 1162 1163 seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", 1164 s->name, sinfo.active_objs, sinfo.num_objs, s->size, 1165 sinfo.objects_per_slab, (1 << sinfo.cache_order)); 1166 1167 seq_printf(m, " : tunables %4u %4u %4u", 1168 sinfo.limit, sinfo.batchcount, sinfo.shared); 1169 seq_printf(m, " : slabdata %6lu %6lu %6lu", 1170 sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); 1171 seq_putc(m, '\n'); 1172 } 1173 1174 static int slab_show(struct seq_file *m, void *p) 1175 { 1176 struct kmem_cache *s = list_entry(p, struct kmem_cache, list); 1177 1178 if (p == slab_caches.next) 1179 print_slabinfo_header(m); 1180 cache_show(s, m); 1181 return 0; 1182 } 1183 1184 void dump_unreclaimable_slab(void) 1185 { 1186 struct kmem_cache *s; 1187 struct slabinfo sinfo; 1188 1189 /* 1190 * Here acquiring slab_mutex is risky since we don't prefer to get 1191 * sleep in oom path. But, without mutex hold, it may introduce a 1192 * risk of crash. 1193 * Use mutex_trylock to protect the list traverse, dump nothing 1194 * without acquiring the mutex. 1195 */ 1196 if (!mutex_trylock(&slab_mutex)) { 1197 pr_warn("excessive unreclaimable slab but cannot dump stats\n"); 1198 return; 1199 } 1200 1201 pr_info("Unreclaimable slab info:\n"); 1202 pr_info("Name Used Total\n"); 1203 1204 list_for_each_entry(s, &slab_caches, list) { 1205 if (s->flags & SLAB_RECLAIM_ACCOUNT) 1206 continue; 1207 1208 get_slabinfo(s, &sinfo); 1209 1210 if (sinfo.num_objs > 0) 1211 pr_info("%-17s %10luKB %10luKB\n", s->name, 1212 (sinfo.active_objs * s->size) / 1024, 1213 (sinfo.num_objs * s->size) / 1024); 1214 } 1215 mutex_unlock(&slab_mutex); 1216 } 1217 1218 /* 1219 * slabinfo_op - iterator that generates /proc/slabinfo 1220 * 1221 * Output layout: 1222 * cache-name 1223 * num-active-objs 1224 * total-objs 1225 * object size 1226 * num-active-slabs 1227 * total-slabs 1228 * num-pages-per-slab 1229 * + further values on SMP and with statistics enabled 1230 */ 1231 static const struct seq_operations slabinfo_op = { 1232 .start = slab_start, 1233 .next = slab_next, 1234 .stop = slab_stop, 1235 .show = slab_show, 1236 }; 1237 1238 static int slabinfo_open(struct inode *inode, struct file *file) 1239 { 1240 return seq_open(file, &slabinfo_op); 1241 } 1242 1243 static const struct proc_ops slabinfo_proc_ops = { 1244 .proc_flags = PROC_ENTRY_PERMANENT, 1245 .proc_open = slabinfo_open, 1246 .proc_read = seq_read, 1247 .proc_lseek = seq_lseek, 1248 .proc_release = seq_release, 1249 }; 1250 1251 static int __init slab_proc_init(void) 1252 { 1253 proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops); 1254 return 0; 1255 } 1256 module_init(slab_proc_init); 1257 1258 #endif /* CONFIG_SLUB_DEBUG */ 1259 1260 static __always_inline __realloc_size(2) void * 1261 __do_krealloc(const void *p, size_t new_size, gfp_t flags) 1262 { 1263 void *ret; 1264 size_t ks; 1265 1266 /* Check for double-free before calling ksize. */ 1267 if (likely(!ZERO_OR_NULL_PTR(p))) { 1268 if (!kasan_check_byte(p)) 1269 return NULL; 1270 ks = ksize(p); 1271 } else 1272 ks = 0; 1273 1274 /* If the object still fits, repoison it precisely. */ 1275 if (ks >= new_size) { 1276 p = kasan_krealloc((void *)p, new_size, flags); 1277 return (void *)p; 1278 } 1279 1280 ret = kmalloc_node_track_caller_noprof(new_size, flags, NUMA_NO_NODE, _RET_IP_); 1281 if (ret && p) { 1282 /* Disable KASAN checks as the object's redzone is accessed. */ 1283 kasan_disable_current(); 1284 memcpy(ret, kasan_reset_tag(p), ks); 1285 kasan_enable_current(); 1286 } 1287 1288 return ret; 1289 } 1290 1291 /** 1292 * krealloc - reallocate memory. The contents will remain unchanged. 1293 * @p: object to reallocate memory for. 1294 * @new_size: how many bytes of memory are required. 1295 * @flags: the type of memory to allocate. 1296 * 1297 * The contents of the object pointed to are preserved up to the 1298 * lesser of the new and old sizes (__GFP_ZERO flag is effectively ignored). 1299 * If @p is %NULL, krealloc() behaves exactly like kmalloc(). If @new_size 1300 * is 0 and @p is not a %NULL pointer, the object pointed to is freed. 1301 * 1302 * Return: pointer to the allocated memory or %NULL in case of error 1303 */ 1304 void *krealloc_noprof(const void *p, size_t new_size, gfp_t flags) 1305 { 1306 void *ret; 1307 1308 if (unlikely(!new_size)) { 1309 kfree(p); 1310 return ZERO_SIZE_PTR; 1311 } 1312 1313 ret = __do_krealloc(p, new_size, flags); 1314 if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) 1315 kfree(p); 1316 1317 return ret; 1318 } 1319 EXPORT_SYMBOL(krealloc_noprof); 1320 1321 /** 1322 * kfree_sensitive - Clear sensitive information in memory before freeing 1323 * @p: object to free memory of 1324 * 1325 * The memory of the object @p points to is zeroed before freed. 1326 * If @p is %NULL, kfree_sensitive() does nothing. 1327 * 1328 * Note: this function zeroes the whole allocated buffer which can be a good 1329 * deal bigger than the requested buffer size passed to kmalloc(). So be 1330 * careful when using this function in performance sensitive code. 1331 */ 1332 void kfree_sensitive(const void *p) 1333 { 1334 size_t ks; 1335 void *mem = (void *)p; 1336 1337 ks = ksize(mem); 1338 if (ks) { 1339 kasan_unpoison_range(mem, ks); 1340 memzero_explicit(mem, ks); 1341 } 1342 kfree(mem); 1343 } 1344 EXPORT_SYMBOL(kfree_sensitive); 1345 1346 size_t ksize(const void *objp) 1347 { 1348 /* 1349 * We need to first check that the pointer to the object is valid. 1350 * The KASAN report printed from ksize() is more useful, then when 1351 * it's printed later when the behaviour could be undefined due to 1352 * a potential use-after-free or double-free. 1353 * 1354 * We use kasan_check_byte(), which is supported for the hardware 1355 * tag-based KASAN mode, unlike kasan_check_read/write(). 1356 * 1357 * If the pointed to memory is invalid, we return 0 to avoid users of 1358 * ksize() writing to and potentially corrupting the memory region. 1359 * 1360 * We want to perform the check before __ksize(), to avoid potentially 1361 * crashing in __ksize() due to accessing invalid metadata. 1362 */ 1363 if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) 1364 return 0; 1365 1366 return kfence_ksize(objp) ?: __ksize(objp); 1367 } 1368 EXPORT_SYMBOL(ksize); 1369 1370 /* Tracepoints definitions. */ 1371 EXPORT_TRACEPOINT_SYMBOL(kmalloc); 1372 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc); 1373 EXPORT_TRACEPOINT_SYMBOL(kfree); 1374 EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free); 1375 1376