crypto/mem_sec.c

   1 /*
   2  * Copyright 2015-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright 2004-2014, Akamai Technologies. All Rights Reserved.
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  */
  10
  11 /*
  12  * This file is in two halves. The first half implements the public API
  13  * to be used by external consumers, and to be used by OpenSSL to store
  14  * data in a "secure arena." The second half implements the secure arena.
  15  * For details on that implementation, see below (look for uppercase
  16  * "SECURE HEAP IMPLEMENTATION").
  17  */
  18 #include "e_os.h"
  19 #include <openssl/crypto.h>
  20
  21 #include <string.h>
  22
  23 #ifndef OPENSSL_NO_SECURE_MEMORY
  24 # if defined(_WIN32)
  25 #  include <windows.h>
  26 # endif
  27 # include <stdlib.h>
  28 # include <assert.h>
  29 # if defined(OPENSSL_SYS_UNIX)
  30 #  include <unistd.h>
  31 # endif
  32 # include <sys/types.h>
  33 # if defined(OPENSSL_SYS_UNIX)
  34 #  include <sys/mman.h>
  35 # endif
  36 # if defined(OPENSSL_SYS_LINUX)
  37 #  include <sys/syscall.h>
  38 #  if defined(SYS_mlock2)
  39 #   include <linux/mman.h>
  40 #   include <errno.h>
  41 #  endif
  42 #  include <sys/param.h>
  43 # endif
  44 # include <sys/stat.h>
  45 # include <fcntl.h>
  46 #endif
  47
  48 #define CLEAR(p, s) OPENSSL_cleanse(p, s)
  49 #ifndef PAGE_SIZE
  50 # define PAGE_SIZE    4096
  51 #endif
  52 #if !defined(MAP_ANON) && defined(MAP_ANONYMOUS)
  53 # define MAP_ANON MAP_ANONYMOUS
  54 #endif
  55
  56 #ifndef OPENSSL_NO_SECURE_MEMORY
  57 static size_t secure_mem_used;
  58
  59 static int secure_mem_initialized;
  60
  61 static CRYPTO_RWLOCK *sec_malloc_lock = NULL;
  62
  63 /*
  64  * These are the functions that must be implemented by a secure heap (sh).
  65  */
  66 static int sh_init(size_t size, size_t minsize);
  67 static void *sh_malloc(size_t size);
  68 static void sh_free(void *ptr);
  69 static void sh_done(void);
  70 static size_t sh_actual_size(char *ptr);
  71 static int sh_allocated(const char *ptr);
  72 #endif
  73
  74 int CRYPTO_secure_malloc_init(size_t size, size_t minsize)
  75 {
  76 #ifndef OPENSSL_NO_SECURE_MEMORY
  77     int ret = 0;
  78
  79     if (!secure_mem_initialized) {
  80         sec_malloc_lock = CRYPTO_THREAD_lock_new();
  81         if (sec_malloc_lock == NULL)
  82             return 0;
  83         if ((ret = sh_init(size, minsize)) != 0) {
  84             secure_mem_initialized = 1;
  85         } else {
  86             CRYPTO_THREAD_lock_free(sec_malloc_lock);
  87             sec_malloc_lock = NULL;
  88         }
  89     }
  90
  91     return ret;
  92 #else
  93     return 0;
  94 #endif /* OPENSSL_NO_SECURE_MEMORY */
  95 }
  96
  97 int CRYPTO_secure_malloc_done(void)
  98 {
  99 #ifndef OPENSSL_NO_SECURE_MEMORY
 100     if (secure_mem_used == 0) {
 101         sh_done();
 102         secure_mem_initialized = 0;
 103         CRYPTO_THREAD_lock_free(sec_malloc_lock);
 104         sec_malloc_lock = NULL;
 105         return 1;
 106     }
 107 #endif /* OPENSSL_NO_SECURE_MEMORY */
 108     return 0;
 109 }
 110
 111 int CRYPTO_secure_malloc_initialized(void)
 112 {
 113 #ifndef OPENSSL_NO_SECURE_MEMORY
 114     return secure_mem_initialized;
 115 #else
 116     return 0;
 117 #endif /* OPENSSL_NO_SECURE_MEMORY */
 118 }
 119
 120 void *CRYPTO_secure_malloc(size_t num, const char *file, int line)
 121 {
 122 #ifndef OPENSSL_NO_SECURE_MEMORY
 123     void *ret;
 124     size_t actual_size;
 125
 126     if (!secure_mem_initialized) {
 127         return CRYPTO_malloc(num, file, line);
 128     }
 129     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 130     ret = sh_malloc(num);
 131     actual_size = ret ? sh_actual_size(ret) : 0;
 132     secure_mem_used += actual_size;
 133     CRYPTO_THREAD_unlock(sec_malloc_lock);
 134     return ret;
 135 #else
 136     return CRYPTO_malloc(num, file, line);
 137 #endif /* OPENSSL_NO_SECURE_MEMORY */
 138 }
 139
 140 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line)
 141 {
 142 #ifndef OPENSSL_NO_SECURE_MEMORY
 143     if (secure_mem_initialized)
 144         /* CRYPTO_secure_malloc() zeroes allocations when it is implemented */
 145         return CRYPTO_secure_malloc(num, file, line);
 146 #endif
 147     return CRYPTO_zalloc(num, file, line);
 148 }
 149
 150 void CRYPTO_secure_free(void *ptr, const char *file, int line)
 151 {
 152 #ifndef OPENSSL_NO_SECURE_MEMORY
 153     size_t actual_size;
 154
 155     if (ptr == NULL)
 156         return;
 157     if (!CRYPTO_secure_allocated(ptr)) {
 158         CRYPTO_free(ptr, file, line);
 159         return;
 160     }
 161     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 162     actual_size = sh_actual_size(ptr);
 163     CLEAR(ptr, actual_size);
 164     secure_mem_used -= actual_size;
 165     sh_free(ptr);
 166     CRYPTO_THREAD_unlock(sec_malloc_lock);
 167 #else
 168     CRYPTO_free(ptr, file, line);
 169 #endif /* OPENSSL_NO_SECURE_MEMORY */
 170 }
 171
 172 void CRYPTO_secure_clear_free(void *ptr, size_t num,
 173                               const char *file, int line)
 174 {
 175 #ifndef OPENSSL_NO_SECURE_MEMORY
 176     size_t actual_size;
 177
 178     if (ptr == NULL)
 179         return;
 180     if (!CRYPTO_secure_allocated(ptr)) {
 181         OPENSSL_cleanse(ptr, num);
 182         CRYPTO_free(ptr, file, line);
 183         return;
 184     }
 185     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 186     actual_size = sh_actual_size(ptr);
 187     CLEAR(ptr, actual_size);
 188     secure_mem_used -= actual_size;
 189     sh_free(ptr);
 190     CRYPTO_THREAD_unlock(sec_malloc_lock);
 191 #else
 192     if (ptr == NULL)
 193         return;
 194     OPENSSL_cleanse(ptr, num);
 195     CRYPTO_free(ptr, file, line);
 196 #endif /* OPENSSL_NO_SECURE_MEMORY */
 197 }
 198
 199 int CRYPTO_secure_allocated(const void *ptr)
 200 {
 201 #ifndef OPENSSL_NO_SECURE_MEMORY
 202     int ret;
 203
 204     if (!secure_mem_initialized)
 205         return 0;
 206     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 207     ret = sh_allocated(ptr);
 208     CRYPTO_THREAD_unlock(sec_malloc_lock);
 209     return ret;
 210 #else
 211     return 0;
 212 #endif /* OPENSSL_NO_SECURE_MEMORY */
 213 }
 214
 215 size_t CRYPTO_secure_used(void)
 216 {
 217 #ifndef OPENSSL_NO_SECURE_MEMORY
 218     return secure_mem_used;
 219 #else
 220     return 0;
 221 #endif /* OPENSSL_NO_SECURE_MEMORY */
 222 }
 223
 224 size_t CRYPTO_secure_actual_size(void *ptr)
 225 {
 226 #ifndef OPENSSL_NO_SECURE_MEMORY
 227     size_t actual_size;
 228
 229     CRYPTO_THREAD_write_lock(sec_malloc_lock);
 230     actual_size = sh_actual_size(ptr);
 231     CRYPTO_THREAD_unlock(sec_malloc_lock);
 232     return actual_size;
 233 #else
 234     return 0;
 235 #endif
 236 }
 237
 238 /*
 239  * SECURE HEAP IMPLEMENTATION
 240  */
 241 #ifndef OPENSSL_NO_SECURE_MEMORY
 242
 243
 244 /*
 245  * The implementation provided here uses a fixed-sized mmap() heap,
 246  * which is locked into memory, not written to core files, and protected
 247  * on either side by an unmapped page, which will catch pointer overruns
 248  * (or underruns) and an attempt to read data out of the secure heap.
 249  * Free'd memory is zero'd or otherwise cleansed.
 250  *
 251  * This is a pretty standard buddy allocator.  We keep areas in a multiple
 252  * of "sh.minsize" units.  The freelist and bitmaps are kept separately,
 253  * so all (and only) data is kept in the mmap'd heap.
 254  *
 255  * This code assumes eight-bit bytes.  The numbers 3 and 7 are all over the
 256  * place.
 257  */
 258
 259 #define ONE ((size_t)1)
 260
 261 # define TESTBIT(t, b)  (t[(b) >> 3] &  (ONE << ((b) & 7)))
 262 # define SETBIT(t, b)   (t[(b) >> 3] |= (ONE << ((b) & 7)))
 263 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(ONE << ((b) & 7))))
 264
 265 #define WITHIN_ARENA(p) \
 266     ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
 267 #define WITHIN_FREELIST(p) \
 268     ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
 269
 270
 271 typedef struct sh_list_st
 272 {
 273     struct sh_list_st *next;
 274     struct sh_list_st **p_next;
 275 } SH_LIST;
 276
 277 typedef struct sh_st
 278 {
 279     char* map_result;
 280     size_t map_size;
 281     char *arena;
 282     size_t arena_size;
 283     char **freelist;
 284     ossl_ssize_t freelist_size;
 285     size_t minsize;
 286     unsigned char *bittable;
 287     unsigned char *bitmalloc;
 288     size_t bittable_size; /* size in bits */
 289 } SH;
 290
 291 static SH sh;
 292
 293 static size_t sh_getlist(char *ptr)
 294 {
 295     ossl_ssize_t list = sh.freelist_size - 1;
 296     size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
 297
 298     for (; bit; bit >>= 1, list--) {
 299         if (TESTBIT(sh.bittable, bit))
 300             break;
 301         OPENSSL_assert((bit & 1) == 0);
 302     }
 303
 304     return list;
 305 }
 306
 307
 308 static int sh_testbit(char *ptr, int list, unsigned char *table)
 309 {
 310     size_t bit;
 311
 312     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 313     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 314     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 315     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 316     return TESTBIT(table, bit);
 317 }
 318
 319 static void sh_clearbit(char *ptr, int list, unsigned char *table)
 320 {
 321     size_t bit;
 322
 323     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 324     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 325     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 326     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 327     OPENSSL_assert(TESTBIT(table, bit));
 328     CLEARBIT(table, bit);
 329 }
 330
 331 static void sh_setbit(char *ptr, int list, unsigned char *table)
 332 {
 333     size_t bit;
 334
 335     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 336     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 337     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 338     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 339     OPENSSL_assert(!TESTBIT(table, bit));
 340     SETBIT(table, bit);
 341 }
 342
 343 static void sh_add_to_list(char **list, char *ptr)
 344 {
 345     SH_LIST *temp;
 346
 347     OPENSSL_assert(WITHIN_FREELIST(list));
 348     OPENSSL_assert(WITHIN_ARENA(ptr));
 349
 350     temp = (SH_LIST *)ptr;
 351     temp->next = *(SH_LIST **)list;
 352     OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
 353     temp->p_next = (SH_LIST **)list;
 354
 355     if (temp->next != NULL) {
 356         OPENSSL_assert((char **)temp->next->p_next == list);
 357         temp->next->p_next = &(temp->next);
 358     }
 359
 360     *list = ptr;
 361 }
 362
 363 static void sh_remove_from_list(char *ptr)
 364 {
 365     SH_LIST *temp, *temp2;
 366
 367     temp = (SH_LIST *)ptr;
 368     if (temp->next != NULL)
 369         temp->next->p_next = temp->p_next;
 370     *temp->p_next = temp->next;
 371     if (temp->next == NULL)
 372         return;
 373
 374     temp2 = temp->next;
 375     OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
 376 }
 377
 378
 379 static int sh_init(size_t size, size_t minsize)
 380 {
 381     int ret;
 382     size_t i;
 383     size_t pgsize;
 384     size_t aligned;
 385 #if defined(_WIN32)
 386     DWORD flOldProtect;
 387     SYSTEM_INFO systemInfo;
 388 #endif
 389
 390     memset(&sh, 0, sizeof(sh));
 391
 392     /* make sure size is a powers of 2 */
 393     OPENSSL_assert(size > 0);
 394     OPENSSL_assert((size & (size - 1)) == 0);
 395     if (size == 0 || (size & (size - 1)) != 0)
 396         goto err;
 397
 398     if (minsize <= sizeof(SH_LIST)) {
 399         OPENSSL_assert(sizeof(SH_LIST) <= 65536);
 400         /*
 401          * Compute the minimum possible allocation size.
 402          * This must be a power of 2 and at least as large as the SH_LIST
 403          * structure.
 404          */
 405         minsize = sizeof(SH_LIST) - 1;
 406         minsize |= minsize >> 1;
 407         minsize |= minsize >> 2;
 408         if (sizeof(SH_LIST) > 16)
 409             minsize |= minsize >> 4;
 410         if (sizeof(SH_LIST) > 256)
 411             minsize |= minsize >> 8;
 412         minsize++;
 413     } else {
 414         /* make sure minsize is a powers of 2 */
 415           OPENSSL_assert((minsize & (minsize - 1)) == 0);
 416           if ((minsize & (minsize - 1)) != 0)
 417               goto err;
 418     }
 419
 420     sh.arena_size = size;
 421     sh.minsize = minsize;
 422     sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
 423
 424     /* Prevent allocations of size 0 later on */
 425     if (sh.bittable_size >> 3 == 0)
 426         goto err;
 427
 428     sh.freelist_size = -1;
 429     for (i = sh.bittable_size; i; i >>= 1)
 430         sh.freelist_size++;
 431
 432     sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof(char *));
 433     OPENSSL_assert(sh.freelist != NULL);
 434     if (sh.freelist == NULL)
 435         goto err;
 436
 437     sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
 438     OPENSSL_assert(sh.bittable != NULL);
 439     if (sh.bittable == NULL)
 440         goto err;
 441
 442     sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
 443     OPENSSL_assert(sh.bitmalloc != NULL);
 444     if (sh.bitmalloc == NULL)
 445         goto err;
 446
 447     /* Allocate space for heap, and two extra pages as guards */
 448 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
 449     {
 450 # if defined(_SC_PAGE_SIZE)
 451         long tmppgsize = sysconf(_SC_PAGE_SIZE);
 452 # else
 453         long tmppgsize = sysconf(_SC_PAGESIZE);
 454 # endif
 455         if (tmppgsize < 1)
 456             pgsize = PAGE_SIZE;
 457         else
 458             pgsize = (size_t)tmppgsize;
 459     }
 460 #elif defined(_WIN32)
 461     GetSystemInfo(&systemInfo);
 462     pgsize = (size_t)systemInfo.dwPageSize;
 463 #else
 464     pgsize = PAGE_SIZE;
 465 #endif
 466     sh.map_size = pgsize + sh.arena_size + pgsize;
 467
 468 #if !defined(_WIN32)
 469 # ifdef MAP_ANON
 470     sh.map_result = mmap(NULL, sh.map_size,
 471                          PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0);
 472 # else
 473     {
 474         int fd;
 475
 476         sh.map_result = MAP_FAILED;
 477         if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
 478             sh.map_result = mmap(NULL, sh.map_size,
 479                                  PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
 480             close(fd);
 481         }
 482     }
 483 # endif
 484     if (sh.map_result == MAP_FAILED)
 485         goto err;
 486 #else
 487     sh.map_result = VirtualAlloc(NULL, sh.map_size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
 488
 489     if (sh.map_result == NULL)
 490             goto err;
 491 #endif
 492
 493     sh.arena = (char *)(sh.map_result + pgsize);
 494     sh_setbit(sh.arena, 0, sh.bittable);
 495     sh_add_to_list(&sh.freelist[0], sh.arena);
 496
 497     /* Now try to add guard pages and lock into memory. */
 498     ret = 1;
 499
 500 #if !defined(_WIN32)
 501     /* Starting guard is already aligned from mmap. */
 502     if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
 503         ret = 2;
 504 #else
 505     if (VirtualProtect(sh.map_result, pgsize, PAGE_NOACCESS, &flOldProtect) == FALSE)
 506         ret = 2;
 507 #endif
 508
 509     /* Ending guard page - need to round up to page boundary */
 510     aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
 511 #if !defined(_WIN32)
 512     if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
 513         ret = 2;
 514 #else
 515     if (VirtualProtect(sh.map_result + aligned, pgsize, PAGE_NOACCESS, &flOldProtect) == FALSE)
 516         ret = 2;
 517 #endif
 518
 519 #if defined(OPENSSL_SYS_LINUX) && defined(MLOCK_ONFAULT) && defined(SYS_mlock2)
 520     if (syscall(SYS_mlock2, sh.arena, sh.arena_size, MLOCK_ONFAULT) < 0) {
 521         if (errno == ENOSYS) {
 522             if (mlock(sh.arena, sh.arena_size) < 0)
 523                 ret = 2;
 524         } else {
 525             ret = 2;
 526         }
 527     }
 528 #elif defined(_WIN32)
 529     if (VirtualLock(sh.arena, sh.arena_size) == FALSE)
 530         ret = 2;
 531 #else
 532     if (mlock(sh.arena, sh.arena_size) < 0)
 533         ret = 2;
 534 #endif
 535 #ifdef MADV_DONTDUMP
 536     if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
 537         ret = 2;
 538 #endif
 539
 540     return ret;
 541
 542  err:
 543     sh_done();
 544     return 0;
 545 }
 546
 547 static void sh_done(void)
 548 {
 549     OPENSSL_free(sh.freelist);
 550     OPENSSL_free(sh.bittable);
 551     OPENSSL_free(sh.bitmalloc);
 552 #if !defined(_WIN32)
 553     if (sh.map_result != MAP_FAILED && sh.map_size)
 554         munmap(sh.map_result, sh.map_size);
 555 #else
 556     if (sh.map_result != NULL && sh.map_size)
 557         VirtualFree(sh.map_result, 0, MEM_RELEASE);
 558 #endif
 559     memset(&sh, 0, sizeof(sh));
 560 }
 561
 562 static int sh_allocated(const char *ptr)
 563 {
 564     return WITHIN_ARENA(ptr) ? 1 : 0;
 565 }
 566
 567 static char *sh_find_my_buddy(char *ptr, int list)
 568 {
 569     size_t bit;
 570     char *chunk = NULL;
 571
 572     bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
 573     bit ^= 1;
 574
 575     if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
 576         chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
 577
 578     return chunk;
 579 }
 580
 581 static void *sh_malloc(size_t size)
 582 {
 583     ossl_ssize_t list, slist;
 584     size_t i;
 585     char *chunk;
 586
 587     if (size > sh.arena_size)
 588         return NULL;
 589
 590     list = sh.freelist_size - 1;
 591     for (i = sh.minsize; i < size; i <<= 1)
 592         list--;
 593     if (list < 0)
 594         return NULL;
 595
 596     /* try to find a larger entry to split */
 597     for (slist = list; slist >= 0; slist--)
 598         if (sh.freelist[slist] != NULL)
 599             break;
 600     if (slist < 0)
 601         return NULL;
 602
 603     /* split larger entry */
 604     while (slist != list) {
 605         char *temp = sh.freelist[slist];
 606
 607         /* remove from bigger list */
 608         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 609         sh_clearbit(temp, slist, sh.bittable);
 610         sh_remove_from_list(temp);
 611         OPENSSL_assert(temp != sh.freelist[slist]);
 612
 613         /* done with bigger list */
 614         slist++;
 615
 616         /* add to smaller list */
 617         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 618         sh_setbit(temp, slist, sh.bittable);
 619         sh_add_to_list(&sh.freelist[slist], temp);
 620         OPENSSL_assert(sh.freelist[slist] == temp);
 621
 622         /* split in 2 */
 623         temp += sh.arena_size >> slist;
 624         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 625         sh_setbit(temp, slist, sh.bittable);
 626         sh_add_to_list(&sh.freelist[slist], temp);
 627         OPENSSL_assert(sh.freelist[slist] == temp);
 628
 629         OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
 630     }
 631
 632     /* peel off memory to hand back */
 633     chunk = sh.freelist[list];
 634     OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
 635     sh_setbit(chunk, list, sh.bitmalloc);
 636     sh_remove_from_list(chunk);
 637
 638     OPENSSL_assert(WITHIN_ARENA(chunk));
 639
 640     /* zero the free list header as a precaution against information leakage */
 641     memset(chunk, 0, sizeof(SH_LIST));
 642
 643     return chunk;
 644 }
 645
 646 static void sh_free(void *ptr)
 647 {
 648     size_t list;
 649     void *buddy;
 650
 651     if (ptr == NULL)
 652         return;
 653     OPENSSL_assert(WITHIN_ARENA(ptr));
 654     if (!WITHIN_ARENA(ptr))
 655         return;
 656
 657     list = sh_getlist(ptr);
 658     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 659     sh_clearbit(ptr, list, sh.bitmalloc);
 660     sh_add_to_list(&sh.freelist[list], ptr);
 661
 662     /* Try to coalesce two adjacent free areas. */
 663     while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
 664         OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
 665         OPENSSL_assert(ptr != NULL);
 666         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 667         sh_clearbit(ptr, list, sh.bittable);
 668         sh_remove_from_list(ptr);
 669         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 670         sh_clearbit(buddy, list, sh.bittable);
 671         sh_remove_from_list(buddy);
 672
 673         list--;
 674
 675         /* Zero the higher addressed block's free list pointers */
 676         memset(ptr > buddy ? ptr : buddy, 0, sizeof(SH_LIST));
 677         if (ptr > buddy)
 678             ptr = buddy;
 679
 680         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 681         sh_setbit(ptr, list, sh.bittable);
 682         sh_add_to_list(&sh.freelist[list], ptr);
 683         OPENSSL_assert(sh.freelist[list] == ptr);
 684     }
 685 }
 686
 687 static size_t sh_actual_size(char *ptr)
 688 {
 689     int list;
 690
 691     OPENSSL_assert(WITHIN_ARENA(ptr));
 692     if (!WITHIN_ARENA(ptr))
 693         return 0;
 694     list = sh_getlist(ptr);
 695     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 696     return sh.arena_size / (ONE << list);
 697 }
 698 #endif /* OPENSSL_NO_SECURE_MEMORY */