crypto/mem_sec.c

   1 /*
   2  * Copyright 2015-2021 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     if (!secure_mem_initialized)
 212         return 0;
 213     /*
 214      * Only read accesses to the arena take place in sh_allocated() and this
 215      * is only changed by the sh_init() and sh_done() calls which are not
 216      * locked.  Hence, it is safe to make this check without a lock too.
 217      */
 218     return sh_allocated(ptr);
 219 #else
 220     return 0;
 221 #endif /* OPENSSL_NO_SECURE_MEMORY */
 222 }
 223
 224 size_t CRYPTO_secure_used(void)
 225 {
 226 #ifndef OPENSSL_NO_SECURE_MEMORY
 227     return secure_mem_used;
 228 #else
 229     return 0;
 230 #endif /* OPENSSL_NO_SECURE_MEMORY */
 231 }
 232
 233 size_t CRYPTO_secure_actual_size(void *ptr)
 234 {
 235 #ifndef OPENSSL_NO_SECURE_MEMORY
 236     size_t actual_size;
 237
 238     if (!CRYPTO_THREAD_write_lock(sec_malloc_lock))
 239         return 0;
 240     actual_size = sh_actual_size(ptr);
 241     CRYPTO_THREAD_unlock(sec_malloc_lock);
 242     return actual_size;
 243 #else
 244     return 0;
 245 #endif
 246 }
 247
 248 /*
 249  * SECURE HEAP IMPLEMENTATION
 250  */
 251 #ifndef OPENSSL_NO_SECURE_MEMORY
 252
 253
 254 /*
 255  * The implementation provided here uses a fixed-sized mmap() heap,
 256  * which is locked into memory, not written to core files, and protected
 257  * on either side by an unmapped page, which will catch pointer overruns
 258  * (or underruns) and an attempt to read data out of the secure heap.
 259  * Free'd memory is zero'd or otherwise cleansed.
 260  *
 261  * This is a pretty standard buddy allocator.  We keep areas in a multiple
 262  * of "sh.minsize" units.  The freelist and bitmaps are kept separately,
 263  * so all (and only) data is kept in the mmap'd heap.
 264  *
 265  * This code assumes eight-bit bytes.  The numbers 3 and 7 are all over the
 266  * place.
 267  */
 268
 269 #define ONE ((size_t)1)
 270
 271 # define TESTBIT(t, b)  (t[(b) >> 3] &  (ONE << ((b) & 7)))
 272 # define SETBIT(t, b)   (t[(b) >> 3] |= (ONE << ((b) & 7)))
 273 # define CLEARBIT(t, b) (t[(b) >> 3] &= (0xFF & ~(ONE << ((b) & 7))))
 274
 275 #define WITHIN_ARENA(p) \
 276     ((char*)(p) >= sh.arena && (char*)(p) < &sh.arena[sh.arena_size])
 277 #define WITHIN_FREELIST(p) \
 278     ((char*)(p) >= (char*)sh.freelist && (char*)(p) < (char*)&sh.freelist[sh.freelist_size])
 279
 280
 281 typedef struct sh_list_st
 282 {
 283     struct sh_list_st *next;
 284     struct sh_list_st **p_next;
 285 } SH_LIST;
 286
 287 typedef struct sh_st
 288 {
 289     char* map_result;
 290     size_t map_size;
 291     char *arena;
 292     size_t arena_size;
 293     char **freelist;
 294     ossl_ssize_t freelist_size;
 295     size_t minsize;
 296     unsigned char *bittable;
 297     unsigned char *bitmalloc;
 298     size_t bittable_size; /* size in bits */
 299 } SH;
 300
 301 static SH sh;
 302
 303 static size_t sh_getlist(char *ptr)
 304 {
 305     ossl_ssize_t list = sh.freelist_size - 1;
 306     size_t bit = (sh.arena_size + ptr - sh.arena) / sh.minsize;
 307
 308     for (; bit; bit >>= 1, list--) {
 309         if (TESTBIT(sh.bittable, bit))
 310             break;
 311         OPENSSL_assert((bit & 1) == 0);
 312     }
 313
 314     return list;
 315 }
 316
 317
 318 static int sh_testbit(char *ptr, int list, unsigned char *table)
 319 {
 320     size_t bit;
 321
 322     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 323     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 324     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 325     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 326     return TESTBIT(table, bit);
 327 }
 328
 329 static void sh_clearbit(char *ptr, int list, unsigned char *table)
 330 {
 331     size_t bit;
 332
 333     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 334     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 335     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 336     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 337     OPENSSL_assert(TESTBIT(table, bit));
 338     CLEARBIT(table, bit);
 339 }
 340
 341 static void sh_setbit(char *ptr, int list, unsigned char *table)
 342 {
 343     size_t bit;
 344
 345     OPENSSL_assert(list >= 0 && list < sh.freelist_size);
 346     OPENSSL_assert(((ptr - sh.arena) & ((sh.arena_size >> list) - 1)) == 0);
 347     bit = (ONE << list) + ((ptr - sh.arena) / (sh.arena_size >> list));
 348     OPENSSL_assert(bit > 0 && bit < sh.bittable_size);
 349     OPENSSL_assert(!TESTBIT(table, bit));
 350     SETBIT(table, bit);
 351 }
 352
 353 static void sh_add_to_list(char **list, char *ptr)
 354 {
 355     SH_LIST *temp;
 356
 357     OPENSSL_assert(WITHIN_FREELIST(list));
 358     OPENSSL_assert(WITHIN_ARENA(ptr));
 359
 360     temp = (SH_LIST *)ptr;
 361     temp->next = *(SH_LIST **)list;
 362     OPENSSL_assert(temp->next == NULL || WITHIN_ARENA(temp->next));
 363     temp->p_next = (SH_LIST **)list;
 364
 365     if (temp->next != NULL) {
 366         OPENSSL_assert((char **)temp->next->p_next == list);
 367         temp->next->p_next = &(temp->next);
 368     }
 369
 370     *list = ptr;
 371 }
 372
 373 static void sh_remove_from_list(char *ptr)
 374 {
 375     SH_LIST *temp, *temp2;
 376
 377     temp = (SH_LIST *)ptr;
 378     if (temp->next != NULL)
 379         temp->next->p_next = temp->p_next;
 380     *temp->p_next = temp->next;
 381     if (temp->next == NULL)
 382         return;
 383
 384     temp2 = temp->next;
 385     OPENSSL_assert(WITHIN_FREELIST(temp2->p_next) || WITHIN_ARENA(temp2->p_next));
 386 }
 387
 388
 389 static int sh_init(size_t size, size_t minsize)
 390 {
 391     int ret;
 392     size_t i;
 393     size_t pgsize;
 394     size_t aligned;
 395 #if defined(_WIN32)
 396     DWORD flOldProtect;
 397     SYSTEM_INFO systemInfo;
 398 #endif
 399
 400     memset(&sh, 0, sizeof(sh));
 401
 402     /* make sure size is a powers of 2 */
 403     OPENSSL_assert(size > 0);
 404     OPENSSL_assert((size & (size - 1)) == 0);
 405     if (size == 0 || (size & (size - 1)) != 0)
 406         goto err;
 407
 408     if (minsize <= sizeof(SH_LIST)) {
 409         OPENSSL_assert(sizeof(SH_LIST) <= 65536);
 410         /*
 411          * Compute the minimum possible allocation size.
 412          * This must be a power of 2 and at least as large as the SH_LIST
 413          * structure.
 414          */
 415         minsize = sizeof(SH_LIST) - 1;
 416         minsize |= minsize >> 1;
 417         minsize |= minsize >> 2;
 418         if (sizeof(SH_LIST) > 16)
 419             minsize |= minsize >> 4;
 420         if (sizeof(SH_LIST) > 256)
 421             minsize |= minsize >> 8;
 422         minsize++;
 423     } else {
 424         /* make sure minsize is a powers of 2 */
 425           OPENSSL_assert((minsize & (minsize - 1)) == 0);
 426           if ((minsize & (minsize - 1)) != 0)
 427               goto err;
 428     }
 429
 430     sh.arena_size = size;
 431     sh.minsize = minsize;
 432     sh.bittable_size = (sh.arena_size / sh.minsize) * 2;
 433
 434     /* Prevent allocations of size 0 later on */
 435     if (sh.bittable_size >> 3 == 0)
 436         goto err;
 437
 438     sh.freelist_size = -1;
 439     for (i = sh.bittable_size; i; i >>= 1)
 440         sh.freelist_size++;
 441
 442     sh.freelist = OPENSSL_zalloc(sh.freelist_size * sizeof(char *));
 443     OPENSSL_assert(sh.freelist != NULL);
 444     if (sh.freelist == NULL)
 445         goto err;
 446
 447     sh.bittable = OPENSSL_zalloc(sh.bittable_size >> 3);
 448     OPENSSL_assert(sh.bittable != NULL);
 449     if (sh.bittable == NULL)
 450         goto err;
 451
 452     sh.bitmalloc = OPENSSL_zalloc(sh.bittable_size >> 3);
 453     OPENSSL_assert(sh.bitmalloc != NULL);
 454     if (sh.bitmalloc == NULL)
 455         goto err;
 456
 457     /* Allocate space for heap, and two extra pages as guards */
 458 #if defined(_SC_PAGE_SIZE) || defined (_SC_PAGESIZE)
 459     {
 460 # if defined(_SC_PAGE_SIZE)
 461         long tmppgsize = sysconf(_SC_PAGE_SIZE);
 462 # else
 463         long tmppgsize = sysconf(_SC_PAGESIZE);
 464 # endif
 465         if (tmppgsize < 1)
 466             pgsize = PAGE_SIZE;
 467         else
 468             pgsize = (size_t)tmppgsize;
 469     }
 470 #elif defined(_WIN32)
 471     GetSystemInfo(&systemInfo);
 472     pgsize = (size_t)systemInfo.dwPageSize;
 473 #else
 474     pgsize = PAGE_SIZE;
 475 #endif
 476     sh.map_size = pgsize + sh.arena_size + pgsize;
 477
 478 #if !defined(_WIN32)
 479 # ifdef MAP_ANON
 480     sh.map_result = mmap(NULL, sh.map_size,
 481                          PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE|MAP_CONCEAL, -1, 0);
 482 # else
 483     {
 484         int fd;
 485
 486         sh.map_result = MAP_FAILED;
 487         if ((fd = open("/dev/zero", O_RDWR)) >= 0) {
 488             sh.map_result = mmap(NULL, sh.map_size,
 489                                  PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
 490             close(fd);
 491         }
 492     }
 493 # endif
 494     if (sh.map_result == MAP_FAILED)
 495         goto err;
 496 #else
 497     sh.map_result = VirtualAlloc(NULL, sh.map_size, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
 498
 499     if (sh.map_result == NULL)
 500             goto err;
 501 #endif
 502
 503     sh.arena = (char *)(sh.map_result + pgsize);
 504     sh_setbit(sh.arena, 0, sh.bittable);
 505     sh_add_to_list(&sh.freelist[0], sh.arena);
 506
 507     /* Now try to add guard pages and lock into memory. */
 508     ret = 1;
 509
 510 #if !defined(_WIN32)
 511     /* Starting guard is already aligned from mmap. */
 512     if (mprotect(sh.map_result, pgsize, PROT_NONE) < 0)
 513         ret = 2;
 514 #else
 515     if (VirtualProtect(sh.map_result, pgsize, PAGE_NOACCESS, &flOldProtect) == FALSE)
 516         ret = 2;
 517 #endif
 518
 519     /* Ending guard page - need to round up to page boundary */
 520     aligned = (pgsize + sh.arena_size + (pgsize - 1)) & ~(pgsize - 1);
 521 #if !defined(_WIN32)
 522     if (mprotect(sh.map_result + aligned, pgsize, PROT_NONE) < 0)
 523         ret = 2;
 524 #else
 525     if (VirtualProtect(sh.map_result + aligned, pgsize, PAGE_NOACCESS, &flOldProtect) == FALSE)
 526         ret = 2;
 527 #endif
 528
 529 #if defined(OPENSSL_SYS_LINUX) && defined(MLOCK_ONFAULT) && defined(SYS_mlock2)
 530     if (syscall(SYS_mlock2, sh.arena, sh.arena_size, MLOCK_ONFAULT) < 0) {
 531         if (errno == ENOSYS) {
 532             if (mlock(sh.arena, sh.arena_size) < 0)
 533                 ret = 2;
 534         } else {
 535             ret = 2;
 536         }
 537     }
 538 #elif defined(_WIN32)
 539     if (VirtualLock(sh.arena, sh.arena_size) == FALSE)
 540         ret = 2;
 541 #else
 542     if (mlock(sh.arena, sh.arena_size) < 0)
 543         ret = 2;
 544 #endif
 545 #ifdef MADV_DONTDUMP
 546     if (madvise(sh.arena, sh.arena_size, MADV_DONTDUMP) < 0)
 547         ret = 2;
 548 #endif
 549
 550     return ret;
 551
 552  err:
 553     sh_done();
 554     return 0;
 555 }
 556
 557 static void sh_done(void)
 558 {
 559     OPENSSL_free(sh.freelist);
 560     OPENSSL_free(sh.bittable);
 561     OPENSSL_free(sh.bitmalloc);
 562 #if !defined(_WIN32)
 563     if (sh.map_result != MAP_FAILED && sh.map_size)
 564         munmap(sh.map_result, sh.map_size);
 565 #else
 566     if (sh.map_result != NULL && sh.map_size)
 567         VirtualFree(sh.map_result, 0, MEM_RELEASE);
 568 #endif
 569     memset(&sh, 0, sizeof(sh));
 570 }
 571
 572 static int sh_allocated(const char *ptr)
 573 {
 574     return WITHIN_ARENA(ptr) ? 1 : 0;
 575 }
 576
 577 static char *sh_find_my_buddy(char *ptr, int list)
 578 {
 579     size_t bit;
 580     char *chunk = NULL;
 581
 582     bit = (ONE << list) + (ptr - sh.arena) / (sh.arena_size >> list);
 583     bit ^= 1;
 584
 585     if (TESTBIT(sh.bittable, bit) && !TESTBIT(sh.bitmalloc, bit))
 586         chunk = sh.arena + ((bit & ((ONE << list) - 1)) * (sh.arena_size >> list));
 587
 588     return chunk;
 589 }
 590
 591 static void *sh_malloc(size_t size)
 592 {
 593     ossl_ssize_t list, slist;
 594     size_t i;
 595     char *chunk;
 596
 597     if (size > sh.arena_size)
 598         return NULL;
 599
 600     list = sh.freelist_size - 1;
 601     for (i = sh.minsize; i < size; i <<= 1)
 602         list--;
 603     if (list < 0)
 604         return NULL;
 605
 606     /* try to find a larger entry to split */
 607     for (slist = list; slist >= 0; slist--)
 608         if (sh.freelist[slist] != NULL)
 609             break;
 610     if (slist < 0)
 611         return NULL;
 612
 613     /* split larger entry */
 614     while (slist != list) {
 615         char *temp = sh.freelist[slist];
 616
 617         /* remove from bigger list */
 618         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 619         sh_clearbit(temp, slist, sh.bittable);
 620         sh_remove_from_list(temp);
 621         OPENSSL_assert(temp != sh.freelist[slist]);
 622
 623         /* done with bigger list */
 624         slist++;
 625
 626         /* add to smaller list */
 627         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 628         sh_setbit(temp, slist, sh.bittable);
 629         sh_add_to_list(&sh.freelist[slist], temp);
 630         OPENSSL_assert(sh.freelist[slist] == temp);
 631
 632         /* split in 2 */
 633         temp += sh.arena_size >> slist;
 634         OPENSSL_assert(!sh_testbit(temp, slist, sh.bitmalloc));
 635         sh_setbit(temp, slist, sh.bittable);
 636         sh_add_to_list(&sh.freelist[slist], temp);
 637         OPENSSL_assert(sh.freelist[slist] == temp);
 638
 639         OPENSSL_assert(temp-(sh.arena_size >> slist) == sh_find_my_buddy(temp, slist));
 640     }
 641
 642     /* peel off memory to hand back */
 643     chunk = sh.freelist[list];
 644     OPENSSL_assert(sh_testbit(chunk, list, sh.bittable));
 645     sh_setbit(chunk, list, sh.bitmalloc);
 646     sh_remove_from_list(chunk);
 647
 648     OPENSSL_assert(WITHIN_ARENA(chunk));
 649
 650     /* zero the free list header as a precaution against information leakage */
 651     memset(chunk, 0, sizeof(SH_LIST));
 652
 653     return chunk;
 654 }
 655
 656 static void sh_free(void *ptr)
 657 {
 658     size_t list;
 659     void *buddy;
 660
 661     if (ptr == NULL)
 662         return;
 663     OPENSSL_assert(WITHIN_ARENA(ptr));
 664     if (!WITHIN_ARENA(ptr))
 665         return;
 666
 667     list = sh_getlist(ptr);
 668     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 669     sh_clearbit(ptr, list, sh.bitmalloc);
 670     sh_add_to_list(&sh.freelist[list], ptr);
 671
 672     /* Try to coalesce two adjacent free areas. */
 673     while ((buddy = sh_find_my_buddy(ptr, list)) != NULL) {
 674         OPENSSL_assert(ptr == sh_find_my_buddy(buddy, list));
 675         OPENSSL_assert(ptr != NULL);
 676         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 677         sh_clearbit(ptr, list, sh.bittable);
 678         sh_remove_from_list(ptr);
 679         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 680         sh_clearbit(buddy, list, sh.bittable);
 681         sh_remove_from_list(buddy);
 682
 683         list--;
 684
 685         /* Zero the higher addressed block's free list pointers */
 686         memset(ptr > buddy ? ptr : buddy, 0, sizeof(SH_LIST));
 687         if (ptr > buddy)
 688             ptr = buddy;
 689
 690         OPENSSL_assert(!sh_testbit(ptr, list, sh.bitmalloc));
 691         sh_setbit(ptr, list, sh.bittable);
 692         sh_add_to_list(&sh.freelist[list], ptr);
 693         OPENSSL_assert(sh.freelist[list] == ptr);
 694     }
 695 }
 696
 697 static size_t sh_actual_size(char *ptr)
 698 {
 699     int list;
 700
 701     OPENSSL_assert(WITHIN_ARENA(ptr));
 702     if (!WITHIN_ARENA(ptr))
 703         return 0;
 704     list = sh_getlist(ptr);
 705     OPENSSL_assert(sh_testbit(ptr, list, sh.bittable));
 706     return sh.arena_size / (ONE << list);
 707 }
 708 #endif /* OPENSSL_NO_SECURE_MEMORY */