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 #  if defined(__FreeBSD__)
  36 #    define MADV_DONTDUMP MADV_NOCORE
  37 #  endif
  38 #  if !defined(MAP_CONCEAL)
  39 #    define MAP_CONCEAL 0
  40 #  endif
  41 # endif
  42 # if defined(OPENSSL_SYS_LINUX)
  43 #  include <sys/syscall.h>
  44 #  if defined(SYS_mlock2)
  45 #   include <linux/mman.h>
  46 #   include <errno.h>
  47 #  endif
  48 #  include <sys/param.h>
  49 # endif
  50 # include <sys/stat.h>
  51 # include <fcntl.h>
  52 #endif
  53
  54 #define CLEAR(p, s) OPENSSL_cleanse(p, s)
  55 #ifndef PAGE_SIZE
  56 # define PAGE_SIZE    4096
  57 #endif
  58 #if !defined(MAP_ANON) && defined(MAP_ANONYMOUS)
  59 # define MAP_ANON MAP_ANONYMOUS
  60 #endif
  61
  62 #ifndef OPENSSL_NO_SECURE_MEMORY
  63 static size_t secure_mem_used;
  64
  65 static int secure_mem_initialized;
  66
  67 static CRYPTO_RWLOCK *sec_malloc_lock = NULL;
  68
  69 /*
  70  * These are the functions that must be implemented by a secure heap (sh).
  71  */
  72 static int sh_init(size_t size, size_t minsize);
  73 static void *sh_malloc(size_t size);
  74 static void sh_free(void *ptr);
  75 static void sh_done(void);
  76 static size_t sh_actual_size(char *ptr);
  77 static int sh_allocated(const char *ptr);
  78 #endif
  79
  80 int CRYPTO_secure_malloc_init(size_t size, size_t minsize)
  81 {
  82 #ifndef OPENSSL_NO_SECURE_MEMORY
  83     int ret = 0;
  84
  85     if (!secure_mem_initialized) {
  86         sec_malloc_lock = CRYPTO_THREAD_lock_new();
  87         if (sec_malloc_lock == NULL)
  88             return 0;
  89         if ((ret = sh_init(size, minsize)) != 0) {
  90             secure_mem_initialized = 1;
  91         } else {
  92             CRYPTO_THREAD_lock_free(sec_malloc_lock);
  93             sec_malloc_lock = NULL;
  94         }
  95     }
  96
  97     return ret;
  98 #else
  99     return 0;
 100 #endif /* OPENSSL_NO_SECURE_MEMORY */
 101 }
 102
 103 int CRYPTO_secure_malloc_done(void)
 104 {
 105 #ifndef OPENSSL_NO_SECURE_MEMORY
 106     if (secure_mem_used == 0) {
 107         sh_done();
 108         secure_mem_initialized = 0;
 109         CRYPTO_THREAD_lock_free(sec_malloc_lock);
 110         sec_malloc_lock = NULL;
 111         return 1;
 112     }
 113 #endif /* OPENSSL_NO_SECURE_MEMORY */
 114     return 0;
 115 }
 116
 117 int CRYPTO_secure_malloc_initialized(void)
 118 {
 119 #ifndef OPENSSL_NO_SECURE_MEMORY
 120     return secure_mem_initialized;
 121 #else
 122     return 0;
 123 #endif /* OPENSSL_NO_SECURE_MEMORY */
 124 }
 125
 126 void *CRYPTO_secure_malloc(size_t num, const char *file, int line)
 127 {
 128 #ifndef OPENSSL_NO_SECURE_MEMORY
 129     void *ret;
 130     size_t actual_size;
 131
 132     if (!secure_mem_initialized) {
 133         return CRYPTO_malloc(num, file, line);
 134     }
 135     if (!CRYPTO_THREAD_write_lock(sec_malloc_lock))
 136         return NULL;
 137     ret = sh_malloc(num);
 138     actual_size = ret ? sh_actual_size(ret) : 0;
 139     secure_mem_used += actual_size;
 140     CRYPTO_THREAD_unlock(sec_malloc_lock);
 141     return ret;
 142 #else
 143     return CRYPTO_malloc(num, file, line);
 144 #endif /* OPENSSL_NO_SECURE_MEMORY */
 145 }
 146
 147 void *CRYPTO_secure_zalloc(size_t num, const char *file, int line)
 148 {
 149 #ifndef OPENSSL_NO_SECURE_MEMORY
 150     if (secure_mem_initialized)
 151         /* CRYPTO_secure_malloc() zeroes allocations when it is implemented */
 152         return CRYPTO_secure_malloc(num, file, line);
 153 #endif
 154     return CRYPTO_zalloc(num, file, line);
 155 }
 156
 157 void CRYPTO_secure_free(void *ptr, const char *file, int line)
 158 {
 159 #ifndef OPENSSL_NO_SECURE_MEMORY
 160     size_t actual_size;
 161
 162     if (ptr == NULL)
 163         return;
 164     if (!CRYPTO_secure_allocated(ptr)) {
 165         CRYPTO_free(ptr, file, line);
 166         return;
 167     }
 168     if (!CRYPTO_THREAD_write_lock(sec_malloc_lock))
 169         return;
 170     actual_size = sh_actual_size(ptr);
 171     CLEAR(ptr, actual_size);
 172     secure_mem_used -= actual_size;
 173     sh_free(ptr);
 174     CRYPTO_THREAD_unlock(sec_malloc_lock);
 175 #else
 176     CRYPTO_free(ptr, file, line);
 177 #endif /* OPENSSL_NO_SECURE_MEMORY */
 178 }
 179
 180 void CRYPTO_secure_clear_free(void *ptr, size_t num,
 181                               const char *file, int line)
 182 {
 183 #ifndef OPENSSL_NO_SECURE_MEMORY
 184     size_t actual_size;
 185
 186     if (ptr == NULL)
 187         return;
 188     if (!CRYPTO_secure_allocated(ptr)) {
 189         OPENSSL_cleanse(ptr, num);
 190         CRYPTO_free(ptr, file, line);
 191         return;
 192     }
 193     if (!CRYPTO_THREAD_write_lock(sec_malloc_lock))
 194         return;
 195     actual_size = sh_actual_size(ptr);
 196     CLEAR(ptr, actual_size);
 197     secure_mem_used -= actual_size;
 198     sh_free(ptr);
 199     CRYPTO_THREAD_unlock(sec_malloc_lock);
 200 #else
 201     if (ptr == NULL)
 202         return;
 203     OPENSSL_cleanse(ptr, num);
 204     CRYPTO_free(ptr, file, line);
 205 #endif /* OPENSSL_NO_SECURE_MEMORY */
 206 }
 207
 208 int CRYPTO_secure_allocated(const void *ptr)
 209 {
 210 #ifndef OPENSSL_NO_SECURE_MEMORY
 211     int ret;
 212
 213     if (!secure_mem_initialized)
 214         return 0;
 215     if (!CRYPTO_THREAD_write_lock(sec_malloc_lock))
 216         return 0;
 217     ret = sh_allocated(ptr);
 218     CRYPTO_THREAD_unlock(sec_malloc_lock);
 219     return ret;
 220 #else
 221     return 0;
 222 #endif /* OPENSSL_NO_SECURE_MEMORY */
 223 }
 224
 225 size_t CRYPTO_secure_used(void)
 226 {
 227 #ifndef OPENSSL_NO_SECURE_MEMORY
 228     return secure_mem_used;
 229 #else
 230     return 0;
 231 #endif /* OPENSSL_NO_SECURE_MEMORY */
 232 }
 233
 234 size_t CRYPTO_secure_actual_size(void *ptr)
 235 {
 236 #ifndef OPENSSL_NO_SECURE_MEMORY
 237     size_t actual_size;
 238
 239     if (!CRYPTO_THREAD_write_lock(sec_malloc_lock))
 240         return 0;
 241     actual_size = sh_actual_size(ptr);
 242     CRYPTO_THREAD_unlock(sec_malloc_lock);
 243     return actual_size;
 244 #else
 245     return 0;
 246 #endif
 247 }
 248
 249 /*
 250  * SECURE HEAP IMPLEMENTATION
 251  */
 252 #ifndef OPENSSL_NO_SECURE_MEMORY
 253
 254
 255 /*
 256  * The implementation provided here uses a fixed-sized mmap() heap,
 257  * which is locked into memory, not written to core files, and protected
 258  * on either side by an unmapped page, which will catch pointer overruns
 259  * (or underruns) and an attempt to read data out of the secure heap.
 260  * Free'd memory is zero'd or otherwise cleansed.
 261  *
 262  * This is a pretty standard buddy allocator.  We keep areas in a multiple
 263  * of "sh.minsize" units.  The freelist and bitmaps are kept separately,
 264  * so all (and only) data is kept in the mmap'd heap.
 265  *
 266  * This code assumes eight-bit bytes.  The numbers 3 and 7 are all over the
 267  * place.
 268  */
 269
 270 #define ONE ((size_t)1)
 271
 272 # define TESTBIT(t, b)  (t[(b) >> 3] &  (ONE << ((b) & 7)))
 273 # define SETBIT(t, b)   (t[(b) >> 3] |= (ONE << ((b) & 7)))
 274 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(ONE << ((b) & 7))))
 275
 276 #define WITHIN_ARENA(p) \
 277     ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
 278 #define WITHIN_FREELIST(p) \
 279     ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
 280
 281
 282 typedef struct sh_list_st
 283 {
 284     struct sh_list_st *next;
 285     struct sh_list_st **p_next;
 286 } SH_LIST;
 287
 288 typedef struct sh_st
 289 {
 290     char* map_result;
 291     size_t map_size;
 292     char *arena;
 293     size_t arena_size;
 294     char **freelist;
 295     ossl_ssize_t freelist_size;
 296     size_t minsize;
 297     unsigned char *bittable;
 298     unsigned char *bitmalloc;
 299     size_t bittable_size; /* size in bits */
 300 } SH;
 301
 302 static SH sh;
 303
 304 static size_t sh_getlist(char *ptr)
 305 {
 306     ossl_ssize_t list = sh.freelist_size - 1;
 307     size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
 308
 309     for (; bit; bit >>= 1, list--) {
 310         if (TESTBIT(sh.bittable, bit))
 311             break;
 312         OPENSSL_assert((bit & 1) == 0);
 313     }
 314
 315     return list;
 316 }
 317
 318
 319 static int sh_testbit(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     return TESTBIT(table, bit);
 328 }
 329
 330 static void sh_clearbit(char *ptr, int list, unsigned char *table)
 331 {
 332     size_t bit;
 333
 334     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 335     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 336     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 337     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 338     OPENSSL_assert(TESTBIT(table, bit));
 339     CLEARBIT(table, bit);
 340 }
 341
 342 static void sh_setbit(char *ptr, int list, unsigned char *table)
 343 {
 344     size_t bit;
 345
 346     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 347     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 348     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 349     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 350     OPENSSL_assert(!TESTBIT(table, bit));
 351     SETBIT(table, bit);
 352 }
 353
 354 static void sh_add_to_list(char **list, char *ptr)
 355 {
 356     SH_LIST *temp;
 357
 358     OPENSSL_assert(WITHIN_FREELIST(list));
 359     OPENSSL_assert(WITHIN_ARENA(ptr));
 360
 361     temp = (SH_LIST *)ptr;
 362     temp->next = *(SH_LIST **)list;
 363     OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
 364     temp->p_next = (SH_LIST **)list;
 365
 366     if (temp->next != NULL) {
 367         OPENSSL_assert((char **)temp->next->p_next == list);
 368         temp->next->p_next = &(temp->next);
 369     }
 370
 371     *list = ptr;
 372 }
 373
 374 static void sh_remove_from_list(char *ptr)
 375 {
 376     SH_LIST *temp, *temp2;
 377
 378     temp = (SH_LIST *)ptr;
 379     if (temp->next != NULL)
 380         temp->next->p_next = temp->p_next;
 381     *temp->p_next = temp->next;
 382     if (temp->next == NULL)
 383         return;
 384
 385     temp2 = temp->next;
 386     OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
 387 }
 388
 389
 390 static int sh_init(size_t size, size_t minsize)
 391 {
 392     int ret;
 393     size_t i;
 394     size_t pgsize;
 395     size_t aligned;
 396 #if defined(_WIN32)
 397     DWORD flOldProtect;
 398     SYSTEM_INFO systemInfo;
 399 #endif
 400
 401     memset(&sh, 0, sizeof(sh));
 402
 403     /* make sure size is a powers of 2 */
 404     OPENSSL_assert(size > 0);
 405     OPENSSL_assert((size & (size - 1)) == 0);
 406     if (size == 0 || (size & (size - 1)) != 0)
 407         goto err;
 408
 409     if (minsize <= sizeof(SH_LIST)) {
 410         OPENSSL_assert(sizeof(SH_LIST) <= 65536);
 411         /*
 412          * Compute the minimum possible allocation size.
 413          * This must be a power of 2 and at least as large as the SH_LIST
 414          * structure.
 415          */
 416         minsize = sizeof(SH_LIST) - 1;
 417         minsize |= minsize >> 1;
 418         minsize |= minsize >> 2;
 419         if (sizeof(SH_LIST) > 16)
 420             minsize |= minsize >> 4;
 421         if (sizeof(SH_LIST) > 256)
 422             minsize |= minsize >> 8;
 423         minsize++;
 424     } else {
 425         /* make sure minsize is a powers of 2 */
 426           OPENSSL_assert((minsize & (minsize - 1)) == 0);
 427           if ((minsize & (minsize - 1)) != 0)
 428               goto err;
 429     }
 430
 431     sh.arena_size = size;
 432     sh.minsize = minsize;
 433     sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
 434
 435     /* Prevent allocations of size 0 later on */
 436     if (sh.bittable_size >> 3 == 0)
 437         goto err;
 438
 439     sh.freelist_size = -1;
 440     for (i = sh.bittable_size; i; i >>= 1)
 441         sh.freelist_size++;
 442
 443     sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof(char *));
 444     OPENSSL_assert(sh.freelist != NULL);
 445     if (sh.freelist == NULL)
 446         goto err;
 447
 448     sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
 449     OPENSSL_assert(sh.bittable != NULL);
 450     if (sh.bittable == NULL)
 451         goto err;
 452
 453     sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
 454     OPENSSL_assert(sh.bitmalloc != NULL);
 455     if (sh.bitmalloc == NULL)
 456         goto err;
 457
 458     /* Allocate space for heap, and two extra pages as guards */
 459 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
 460     {
 461 # if defined(_SC_PAGE_SIZE)
 462         long tmppgsize = sysconf(_SC_PAGE_SIZE);
 463 # else
 464         long tmppgsize = sysconf(_SC_PAGESIZE);
 465 # endif
 466         if (tmppgsize < 1)
 467             pgsize = PAGE_SIZE;
 468         else
 469             pgsize = (size_t)tmppgsize;
 470     }
 471 #elif defined(_WIN32)
 472     GetSystemInfo(&systemInfo);
 473     pgsize = (size_t)systemInfo.dwPageSize;
 474 #else
 475     pgsize = PAGE_SIZE;
 476 #endif
 477     sh.map_size = pgsize + sh.arena_size + pgsize;
 478
 479 #if !defined(_WIN32)
 480 # ifdef MAP_ANON
 481     sh.map_result = mmap(NULL, sh.map_size,
 482                          PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE|MAP_CONCEAL, -1, 0);
 483 # else
 484     {
 485         int fd;
 486
 487         sh.map_result = MAP_FAILED;
 488         if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
 489             sh.map_result = mmap(NULL, sh.map_size,
 490                                  PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
 491             close(fd);
 492         }
 493     }
 494 # endif
 495     if (sh.map_result == MAP_FAILED)
 496         goto err;
 497 #else
 498     sh.map_result = VirtualAlloc(NULL, sh.map_size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
 499
 500     if (sh.map_result == NULL)
 501             goto err;
 502 #endif
 503
 504     sh.arena = (char *)(sh.map_result + pgsize);
 505     sh_setbit(sh.arena, 0, sh.bittable);
 506     sh_add_to_list(&sh.freelist[0], sh.arena);
 507
 508     /* Now try to add guard pages and lock into memory. */
 509     ret = 1;
 510
 511 #if !defined(_WIN32)
 512     /* Starting guard is already aligned from mmap. */
 513     if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
 514         ret = 2;
 515 #else
 516     if (VirtualProtect(sh.map_result, pgsize, PAGE_NOACCESS, &flOldProtect) == FALSE)
 517         ret = 2;
 518 #endif
 519
 520     /* Ending guard page - need to round up to page boundary */
 521     aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
 522 #if !defined(_WIN32)
 523     if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
 524         ret = 2;
 525 #else
 526     if (VirtualProtect(sh.map_result + aligned, pgsize, PAGE_NOACCESS, &flOldProtect) == FALSE)
 527         ret = 2;
 528 #endif
 529
 530 #if defined(OPENSSL_SYS_LINUX) && defined(MLOCK_ONFAULT) && defined(SYS_mlock2)
 531     if (syscall(SYS_mlock2, sh.arena, sh.arena_size, MLOCK_ONFAULT) < 0) {
 532         if (errno == ENOSYS) {
 533             if (mlock(sh.arena, sh.arena_size) < 0)
 534                 ret = 2;
 535         } else {
 536             ret = 2;
 537         }
 538     }
 539 #elif defined(_WIN32)
 540     if (VirtualLock(sh.arena, sh.arena_size) == FALSE)
 541         ret = 2;
 542 #else
 543     if (mlock(sh.arena, sh.arena_size) < 0)
 544         ret = 2;
 545 #endif
 546 #ifdef MADV_DONTDUMP
 547     if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
 548         ret = 2;
 549 #endif
 550
 551     return ret;
 552
 553  err:
 554     sh_done();
 555     return 0;
 556 }
 557
 558 static void sh_done(void)
 559 {
 560     OPENSSL_free(sh.freelist);
 561     OPENSSL_free(sh.bittable);
 562     OPENSSL_free(sh.bitmalloc);
 563 #if !defined(_WIN32)
 564     if (sh.map_result != MAP_FAILED && sh.map_size)
 565         munmap(sh.map_result, sh.map_size);
 566 #else
 567     if (sh.map_result != NULL && sh.map_size)
 568         VirtualFree(sh.map_result, 0, MEM_RELEASE);
 569 #endif
 570     memset(&sh, 0, sizeof(sh));
 571 }
 572
 573 static int sh_allocated(const char *ptr)
 574 {
 575     return WITHIN_ARENA(ptr) ? 1 : 0;
 576 }
 577
 578 static char *sh_find_my_buddy(char *ptr, int list)
 579 {
 580     size_t bit;
 581     char *chunk = NULL;
 582
 583     bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
 584     bit ^= 1;
 585
 586     if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
 587         chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
 588
 589     return chunk;
 590 }
 591
 592 static void *sh_malloc(size_t size)
 593 {
 594     ossl_ssize_t list, slist;
 595     size_t i;
 596     char *chunk;
 597
 598     if (size > sh.arena_size)
 599         return NULL;
 600
 601     list = sh.freelist_size - 1;
 602     for (i = sh.minsize; i < size; i <<= 1)
 603         list--;
 604     if (list < 0)
 605         return NULL;
 606
 607     /* try to find a larger entry to split */
 608     for (slist = list; slist >= 0; slist--)
 609         if (sh.freelist[slist] != NULL)
 610             break;
 611     if (slist < 0)
 612         return NULL;
 613
 614     /* split larger entry */
 615     while (slist != list) {
 616         char *temp = sh.freelist[slist];
 617
 618         /* remove from bigger list */
 619         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 620         sh_clearbit(temp, slist, sh.bittable);
 621         sh_remove_from_list(temp);
 622         OPENSSL_assert(temp != sh.freelist[slist]);
 623
 624         /* done with bigger list */
 625         slist++;
 626
 627         /* add to smaller list */
 628         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 629         sh_setbit(temp, slist, sh.bittable);
 630         sh_add_to_list(&sh.freelist[slist], temp);
 631         OPENSSL_assert(sh.freelist[slist] == temp);
 632
 633         /* split in 2 */
 634         temp += sh.arena_size >> slist;
 635         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 636         sh_setbit(temp, slist, sh.bittable);
 637         sh_add_to_list(&sh.freelist[slist], temp);
 638         OPENSSL_assert(sh.freelist[slist] == temp);
 639
 640         OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
 641     }
 642
 643     /* peel off memory to hand back */
 644     chunk = sh.freelist[list];
 645     OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
 646     sh_setbit(chunk, list, sh.bitmalloc);
 647     sh_remove_from_list(chunk);
 648
 649     OPENSSL_assert(WITHIN_ARENA(chunk));
 650
 651     /* zero the free list header as a precaution against information leakage */
 652     memset(chunk, 0, sizeof(SH_LIST));
 653
 654     return chunk;
 655 }
 656
 657 static void sh_free(void *ptr)
 658 {
 659     size_t list;
 660     void *buddy;
 661
 662     if (ptr == NULL)
 663         return;
 664     OPENSSL_assert(WITHIN_ARENA(ptr));
 665     if (!WITHIN_ARENA(ptr))
 666         return;
 667
 668     list = sh_getlist(ptr);
 669     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 670     sh_clearbit(ptr, list, sh.bitmalloc);
 671     sh_add_to_list(&sh.freelist[list], ptr);
 672
 673     /* Try to coalesce two adjacent free areas. */
 674     while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
 675         OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
 676         OPENSSL_assert(ptr != NULL);
 677         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 678         sh_clearbit(ptr, list, sh.bittable);
 679         sh_remove_from_list(ptr);
 680         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 681         sh_clearbit(buddy, list, sh.bittable);
 682         sh_remove_from_list(buddy);
 683
 684         list--;
 685
 686         /* Zero the higher addressed block's free list pointers */
 687         memset(ptr > buddy ? ptr : buddy, 0, sizeof(SH_LIST));
 688         if (ptr > buddy)
 689             ptr = buddy;
 690
 691         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 692         sh_setbit(ptr, list, sh.bittable);
 693         sh_add_to_list(&sh.freelist[list], ptr);
 694         OPENSSL_assert(sh.freelist[list] == ptr);
 695     }
 696 }
 697
 698 static size_t sh_actual_size(char *ptr)
 699 {
 700     int list;
 701
 702     OPENSSL_assert(WITHIN_ARENA(ptr));
 703     if (!WITHIN_ARENA(ptr))
 704         return 0;
 705     list = sh_getlist(ptr);
 706     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 707     return sh.arena_size / (ONE << list);
 708 }
 709 #endif /* OPENSSL_NO_SECURE_MEMORY */