smatch_buf_comparison.c

   1 /*
   2  * Copyright (C) 2012 Oracle.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 /*
  19  * The point here is to store that a buffer has x bytes even if we don't know
  20  * the value of x.
  21  *
  22  */
  23
  24 #include "smatch.h"
  25 #include "smatch_extra.h"
  26 #include "smatch_slist.h"
  27
  28 static int size_id;
  29 static int link_id;
  30
  31 /*
  32  * There is a bunch of code which does this:
  33  *
  34  *     if (size)
  35  *         foo = malloc(size);
  36  *
  37  * So if "size" is non-zero then the size of "foo" is size.  But really it's
  38  * also true if size is zero.  It's just better to assume to not trample over
  39  * the data that we have by merging &undefined states.
  40  *
  41  */
  42 static struct smatch_state *unmatched_state(struct sm_state *sm)
  43 {
  44         return sm->state;
  45 }
  46
  47 static struct smatch_state *merge_links(struct smatch_state *s1, struct smatch_state *s2)
  48 {
  49         struct expression *expr1, *expr2;
  50
  51         expr1 = s1->data;
  52         expr2 = s2->data;
  53
  54         if (expr1 && expr2 && expr_equiv(expr1, expr2))
  55                 return s1;
  56         return &merged;
  57 }
  58
  59 static void match_link_modify(struct sm_state *sm, struct expression *mod_expr)
  60 {
  61         struct expression *expr;
  62         struct sm_state *tmp;
  63
  64         expr = sm->state->data;
  65         if (expr) {
  66                 set_state_expr(size_id, expr, &undefined);
  67                 set_state(link_id, sm->name, sm->sym, &undefined);
  68                 return;
  69         }
  70
  71         FOR_EACH_PTR(sm->possible, tmp) {
  72                 expr = tmp->state->data;
  73                 if (expr)
  74                         set_state_expr(size_id, expr, &undefined);
  75         } END_FOR_EACH_PTR(tmp);
  76         set_state(link_id, sm->name, sm->sym, &undefined);
  77 }
  78
  79 static const char *limit_map[] = {
  80         "byte_count",
  81         "elem_count",
  82         "elem_last",
  83         "used_count",
  84         "used_last",
  85 };
  86
  87 int state_to_limit(struct smatch_state *state)
  88 {
  89         int i;
  90
  91         if (!state || !state->data)
  92                 return -1;
  93
  94         for (i = 0; i < ARRAY_SIZE(limit_map); i++) {
  95                 if (strncmp(state->name, limit_map[i], strlen(limit_map[i])) == 0)
  96                         return i + BYTE_COUNT;
  97         }
  98
  99         return -1;
 100 }
 101
 102 const char *limit_type_str(unsigned int limit_type)
 103 {
 104         if (limit_type - BYTE_COUNT >= ARRAY_SIZE(limit_map)) {
 105                 sm_msg("internal: wrong size type %u", limit_type);
 106                 return "unknown";
 107         }
 108
 109         return limit_map[limit_type - BYTE_COUNT];
 110 }
 111
 112 static struct smatch_state *alloc_compare_size(int limit_type, struct expression *expr)
 113 {
 114         struct smatch_state *state;
 115         char *name;
 116         char buf[256];
 117
 118         state = __alloc_smatch_state(0);
 119         expr = strip_expr(expr);
 120         name = expr_to_str(expr);
 121         snprintf(buf, sizeof(buf), "%s %s", limit_type_str(limit_type), name);
 122         state->name = alloc_sname(buf);
 123         free_string(name);
 124         state->data = expr;
 125         return state;
 126 }
 127
 128 static int bytes_per_element(struct expression *expr)
 129 {
 130         struct symbol *type;
 131
 132         type = get_type(expr);
 133         if (!type)
 134                 return 0;
 135
 136         if (type->type != SYM_PTR && type->type != SYM_ARRAY)
 137                 return 0;
 138
 139         type = get_base_type(type);
 140         return type_bytes(type);
 141 }
 142
 143 static void db_save_type_links(struct expression *array, int type_limit, struct expression *size)
 144 {
 145         const char *array_name;
 146
 147         array_name = get_data_info_name(array);
 148         if (!array_name)
 149                 array_name = "";
 150         sql_insert_data_info(size, type_limit, array_name);
 151 }
 152
 153 static void match_alloc_helper(struct expression *pointer, struct expression *size)
 154 {
 155         struct expression *tmp;
 156         struct sm_state *sm;
 157         int limit_type = ELEM_COUNT;
 158         sval_t sval;
 159         int cnt = 0;
 160
 161         pointer = strip_expr(pointer);
 162         size = strip_expr(size);
 163         if (!size || !pointer)
 164                 return;
 165
 166         while ((tmp = get_assigned_expr(size))) {
 167                 size = strip_expr(tmp);
 168                 if (cnt++ > 5)
 169                         break;
 170         }
 171
 172         if (size->type == EXPR_BINOP && size->op == '*') {
 173                 struct expression *mult_left, *mult_right;
 174
 175                 mult_left = strip_expr(size->left);
 176                 mult_right = strip_expr(size->right);
 177
 178                 if (get_implied_value(mult_left, &sval) &&
 179                     sval.value == bytes_per_element(pointer))
 180                         size = mult_right;
 181                 else if (get_implied_value(mult_right, &sval) &&
 182                     sval.value == bytes_per_element(pointer))
 183                         size = mult_left;
 184                 else
 185                         return;
 186         }
 187
 188         /* Only save links to variables, not fixed sizes */
 189         if (get_value(size, &sval))
 190                 return;
 191
 192         if (size->type == EXPR_BINOP && size->op == '+' &&
 193             get_value(size->right, &sval) && sval.value == 1) {
 194                 size = size->left;
 195                 limit_type = ELEM_LAST;
 196         }
 197
 198         db_save_type_links(pointer, limit_type, size);
 199         sm = set_state_expr(size_id, pointer, alloc_compare_size(limit_type, size));
 200         if (!sm)
 201                 return;
 202         set_state_expr(link_id, size, alloc_state_expr(pointer));
 203 }
 204
 205 static void match_alloc(const char *fn, struct expression *expr, void *_size_arg)
 206 {
 207         int size_arg = PTR_INT(_size_arg);
 208         struct expression *pointer, *call, *arg;
 209
 210         pointer = strip_expr(expr->left);
 211         call = strip_expr(expr->right);
 212         arg = get_argument_from_call_expr(call->args, size_arg);
 213         match_alloc_helper(pointer, arg);
 214 }
 215
 216 static void match_calloc(const char *fn, struct expression *expr, void *_start_arg)
 217 {
 218         int start_arg = PTR_INT(_start_arg);
 219         struct expression *pointer, *call, *arg;
 220         struct sm_state *tmp;
 221         int limit_type = ELEM_COUNT;
 222         sval_t sval;
 223
 224         pointer = strip_expr(expr->left);
 225         call = strip_expr(expr->right);
 226         arg = get_argument_from_call_expr(call->args, start_arg);
 227         if (get_implied_value(arg, &sval) &&
 228             sval.value == bytes_per_element(pointer))
 229                 arg = get_argument_from_call_expr(call->args, start_arg + 1);
 230
 231         if (arg->type == EXPR_BINOP && arg->op == '+' &&
 232             get_value(arg->right, &sval) && sval.value == 1) {
 233                 arg = arg->left;
 234                 limit_type = ELEM_LAST;
 235         }
 236
 237         db_save_type_links(pointer, limit_type, arg);
 238         tmp = set_state_expr(size_id, pointer, alloc_compare_size(limit_type, arg));
 239         if (!tmp)
 240                 return;
 241         set_state_expr(link_id, arg, alloc_state_expr(pointer));
 242 }
 243
 244 struct expression *get_size_variable(struct expression *buf, int *limit_type)
 245 {
 246         struct smatch_state *state;
 247
 248         state = get_state_expr(size_id, buf);
 249         if (!state)
 250                 return NULL;
 251         *limit_type = state_to_limit(state);
 252         return state->data;
 253 }
 254
 255 struct expression *get_array_variable(struct expression *size)
 256 {
 257         struct smatch_state *state;
 258
 259         state = get_state_expr(link_id, size);
 260         if (state)
 261                 return state->data;
 262         return NULL;
 263 }
 264
 265 static void array_check(struct expression *expr)
 266 {
 267         struct expression *array;
 268         struct expression *size;
 269         struct expression *offset;
 270         char *array_str, *offset_str;
 271         int limit_type;
 272
 273         expr = strip_expr(expr);
 274         if (!is_array(expr))
 275                 return;
 276
 277         array = get_array_base(expr);
 278         size = get_size_variable(array, &limit_type);
 279         if (!size)
 280                 return;
 281         if (limit_type != ELEM_COUNT)
 282                 return;
 283         offset = get_array_offset(expr);
 284         if (!possible_comparison(size, SPECIAL_EQUAL, offset))
 285                 return;
 286
 287         array_str = expr_to_str(array);
 288         offset_str = expr_to_str(offset);
 289         sm_warning("potentially one past the end of array '%s[%s]'", array_str, offset_str);
 290         free_string(array_str);
 291         free_string(offset_str);
 292 }
 293
 294 struct db_info {
 295         char *name;
 296         int ret;
 297 };
 298
 299 static int db_limitter_callback(void *_info, int argc, char **argv, char **azColName)
 300 {
 301         struct db_info *info = _info;
 302
 303         /*
 304          * If possible the limitters are tied to the struct they limit.  If we
 305          * aren't sure which struct they limit then we use them as limitters for
 306          * everything.
 307          */
 308         if (!info->name || argv[0][0] == '\0' || strcmp(info->name, argv[0]) == 0)
 309                 info->ret = 1;
 310         return 0;
 311 }
 312
 313 static char *vsl_to_data_info_name(const char *name, struct var_sym_list *vsl)
 314 {
 315         struct var_sym *vs;
 316         struct symbol *type;
 317         static char buf[80];
 318         const char *p;
 319
 320         if (ptr_list_size((struct ptr_list *)vsl) != 1)
 321                 return NULL;
 322         vs = first_ptr_list((struct ptr_list *)vsl);
 323
 324         type = get_real_base_type(vs->sym);
 325         if (!type || type->type != SYM_PTR)
 326                 goto top_level_name;
 327         type = get_real_base_type(type);
 328         if (!type || type->type != SYM_STRUCT)
 329                 goto top_level_name;
 330         if (!type->ident)
 331                 goto top_level_name;
 332
 333         p = name;
 334         while ((name = strstr(p, "->")))
 335                 p = name + 2;
 336
 337         snprintf(buf, sizeof(buf),"(struct %s)->%s", type->ident->name, p);
 338         return alloc_sname(buf);
 339
 340 top_level_name:
 341         if (!(vs->sym->ctype.modifiers & MOD_TOPLEVEL))
 342                 return NULL;
 343         if (vs->sym->ctype.modifiers & MOD_STATIC)
 344                 snprintf(buf, sizeof(buf),"static %s", name);
 345         else
 346                 snprintf(buf, sizeof(buf),"global %s", name);
 347         return alloc_sname(buf);
 348 }
 349
 350 int db_var_is_array_limit(struct expression *array, const char *name, struct var_sym_list *vsl)
 351 {
 352         char *size_name;
 353         char *array_name = get_data_info_name(array);
 354         struct db_info db_info = {.name = array_name,};
 355
 356         size_name = vsl_to_data_info_name(name, vsl);
 357         if (!size_name)
 358                 return 0;
 359
 360         run_sql(db_limitter_callback, &db_info,
 361                 "select value from data_info where type = %d and data = '%s';",
 362                 ARRAY_LEN, size_name);
 363
 364         return db_info.ret;
 365 }
 366
 367 int buf_comparison_index_ok(struct expression *expr)
 368 {
 369         struct expression *array;
 370         struct expression *size;
 371         struct expression *offset;
 372         int limit_type;
 373         int comparison;
 374
 375         array = get_array_base(expr);
 376         size = get_size_variable(array, &limit_type);
 377         if (!size)
 378                 return 0;
 379         offset = get_array_offset(expr);
 380         comparison = get_comparison(offset, size);
 381         if (!comparison)
 382                 return 0;
 383
 384         if ((limit_type == ELEM_COUNT || limit_type == ELEM_LAST) &&
 385             (comparison == '<' || comparison == SPECIAL_UNSIGNED_LT))
 386                 return 1;
 387         if (limit_type == ELEM_LAST &&
 388             (comparison == SPECIAL_LTE ||
 389              comparison == SPECIAL_UNSIGNED_LTE ||
 390              comparison == SPECIAL_EQUAL))
 391                 return 1;
 392
 393         return 0;
 394 }
 395
 396 static int known_access_ok_numbers(struct expression *expr)
 397 {
 398         struct expression *array;
 399         struct expression *offset;
 400         sval_t max;
 401         int size;
 402
 403         array = get_array_base(expr);
 404         offset = get_array_offset(expr);
 405
 406         size = get_array_size(array);
 407         if (size <= 0)
 408                 return 0;
 409
 410         get_absolute_max(offset, &max);
 411         if (max.uvalue < size)
 412                 return 1;
 413         return 0;
 414 }
 415
 416 static void array_check_data_info(struct expression *expr)
 417 {
 418         struct expression *array;
 419         struct expression *offset;
 420         struct state_list *slist;
 421         struct sm_state *sm;
 422         struct compare_data *comp;
 423         char *offset_name;
 424         const char *equal_name = NULL;
 425
 426         expr = strip_expr(expr);
 427         if (!is_array(expr))
 428                 return;
 429
 430         if (known_access_ok_numbers(expr))
 431                 return;
 432         if (buf_comparison_index_ok(expr))
 433                 return;
 434
 435         array = get_array_base(expr);
 436         offset = get_array_offset(expr);
 437         offset_name = expr_to_var(offset);
 438         if (!offset_name)
 439                 return;
 440         slist = get_all_possible_equal_comparisons(offset);
 441         if (!slist)
 442                 goto free;
 443
 444         FOR_EACH_PTR(slist, sm) {
 445                 comp = sm->state->data;
 446                 if (strcmp(comp->left_var, offset_name) == 0) {
 447                         if (db_var_is_array_limit(array, comp->right_var, comp->right_vsl)) {
 448                                 equal_name = comp->right_var;
 449                                 break;
 450                         }
 451                 } else if (strcmp(comp->right_var, offset_name) == 0) {
 452                         if (db_var_is_array_limit(array, comp->left_var, comp->left_vsl)) {
 453                                 equal_name = comp->left_var;
 454                                 break;
 455                         }
 456                 }
 457         } END_FOR_EACH_PTR(sm);
 458
 459         if (equal_name) {
 460                 char *array_name = expr_to_str(array);
 461
 462                 sm_warning("potential off by one '%s[]' limit '%s'", array_name, equal_name);
 463                 free_string(array_name);
 464         }
 465
 466 free:
 467         free_slist(&slist);
 468         free_string(offset_name);
 469 }
 470
 471 static void add_allocation_function(const char *func, void *call_back, int param)
 472 {
 473         add_function_assign_hook(func, call_back, INT_PTR(param));
 474 }
 475
 476 static int is_sizeof(struct expression *expr)
 477 {
 478         const char *name;
 479
 480         if (expr->type == EXPR_SIZEOF)
 481                 return 1;
 482         name = pos_ident(expr->pos);
 483         if (name && strcmp(name, "sizeof") == 0)
 484                 return 1;
 485         return 0;
 486 }
 487
 488 static int match_size_binop(struct expression *size, struct expression *expr, int *limit_type)
 489 {
 490         int orig_type = *limit_type;
 491         struct expression *left;
 492         sval_t sval;
 493
 494         left = expr->left;
 495         if (!expr_equiv(size, left))
 496                 return 0;
 497
 498         if (expr->op == '-' &&
 499             get_value(expr->right, &sval) &&
 500             sval.value == 1 &&
 501             orig_type == ELEM_COUNT) {
 502                 *limit_type = ELEM_LAST;
 503                 return 1;
 504         }
 505
 506         if (expr->op == '+' &&
 507             get_value(expr->right, &sval) &&
 508             sval.value == 1 &&
 509             orig_type == ELEM_LAST) {
 510                 *limit_type = ELEM_COUNT;
 511                 return 1;
 512         }
 513
 514         if (expr->op == '*' &&
 515             is_sizeof(expr->right) &&
 516             orig_type == ELEM_COUNT) {
 517                 *limit_type = BYTE_COUNT;
 518                 return 1;
 519         }
 520
 521         if (expr->op == '/' &&
 522             is_sizeof(expr->right) &&
 523             orig_type == BYTE_COUNT) {
 524                 *limit_type = ELEM_COUNT;
 525                 return 1;
 526         }
 527
 528         return 0;
 529 }
 530
 531 static char *buf_size_param_comparison(struct expression *array, struct expression_list *args, int *limit_type)
 532 {
 533         struct expression *tmp, *arg;
 534         struct expression *size;
 535         static char buf[32];
 536         int i;
 537
 538         size = get_size_variable(array, limit_type);
 539         if (!size)
 540                 return NULL;
 541
 542         if (*limit_type == USED_LAST)
 543                 *limit_type = ELEM_LAST;
 544         if (*limit_type == USED_COUNT)
 545                 *limit_type = ELEM_COUNT;
 546
 547         i = -1;
 548         FOR_EACH_PTR(args, tmp) {
 549                 i++;
 550                 arg = tmp;
 551                 if (arg == array)
 552                         continue;
 553                 if (expr_equiv(arg, size) ||
 554                     (arg->type == EXPR_BINOP &&
 555                      match_size_binop(size, arg, limit_type))) {
 556                         snprintf(buf, sizeof(buf), "==$%d", i);
 557                         return buf;
 558                 }
 559         } END_FOR_EACH_PTR(tmp);
 560
 561         return NULL;
 562 }
 563
 564 static void match_call(struct expression *call)
 565 {
 566         struct expression *arg;
 567         char *compare;
 568         int param;
 569         char buf[5];
 570         int limit_type;
 571
 572         param = -1;
 573         FOR_EACH_PTR(call->args, arg) {
 574                 param++;
 575                 if (!is_pointer(arg))
 576                         continue;
 577                 compare = buf_size_param_comparison(arg, call->args, &limit_type);
 578                 if (!compare)
 579                         continue;
 580                 snprintf(buf, sizeof(buf), "%d", limit_type);
 581                 sql_insert_caller_info(call, limit_type, param, compare, buf);
 582         } END_FOR_EACH_PTR(arg);
 583 }
 584
 585 static int get_param(int param, char **name, struct symbol **sym)
 586 {
 587         struct symbol *arg;
 588         int i;
 589
 590         i = 0;
 591         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 592                 /*
 593                  * this is a temporary hack to work around a bug (I think in sparse?)
 594                  * 2.6.37-rc1:fs/reiserfs/journal.o
 595                  * If there is a function definition without parameter name found
 596                  * after a function implementation then it causes a crash.
 597                  * int foo() {}
 598                  * int bar(char *);
 599                  */
 600                 if (arg->ident->name < (char *)100)
 601                         continue;
 602                 if (i == param) {
 603                         *name = arg->ident->name;
 604                         *sym = arg;
 605                         return TRUE;
 606                 }
 607                 i++;
 608         } END_FOR_EACH_PTR(arg);
 609
 610         return FALSE;
 611 }
 612
 613 static void set_param_compare(const char *array_name, struct symbol *array_sym, char *key, char *value)
 614 {
 615         struct expression *array_expr;
 616         struct expression *size_expr;
 617         struct symbol *size_sym;
 618         char *size_name;
 619         long param;
 620         struct sm_state *tmp;
 621         int limit_type;
 622
 623         if (strncmp(key, "==$", 3) != 0)
 624                 return;
 625         param = strtol(key + 3, NULL, 10);
 626         if (!get_param(param, &size_name, &size_sym))
 627                 return;
 628         array_expr = symbol_expression(array_sym);
 629         size_expr = symbol_expression(size_sym);
 630         limit_type = strtol(value, NULL, 10);
 631
 632         tmp = set_state_expr(size_id, array_expr, alloc_compare_size(limit_type, size_expr));
 633         if (!tmp)
 634                 return;
 635         set_state_expr(link_id, size_expr, alloc_state_expr(array_expr));
 636 }
 637
 638 static void set_implied(struct expression *call, struct expression *array_expr, char *key, char *value)
 639 {
 640         struct expression *size_expr;
 641         struct symbol *size_sym;
 642         char *size_name;
 643         long param;
 644         struct sm_state *tmp;
 645         int limit_type;
 646
 647         if (strncmp(key, "==$", 3) != 0)
 648                 return;
 649         param = strtol(key + 3, NULL, 10);
 650         if (!get_param(param, &size_name, &size_sym))
 651                 return;
 652         size_expr = symbol_expression(size_sym);
 653
 654         limit_type = strtol(value, NULL, 10);
 655         tmp = set_state_expr(size_id, array_expr, alloc_compare_size(limit_type, size_expr));
 656         if (!tmp)
 657                 return;
 658         set_state_expr(link_id, size_expr, alloc_state_expr(array_expr));
 659 }
 660
 661 static void munge_start_states(struct statement *stmt)
 662 {
 663         struct state_list *slist = NULL;
 664         struct sm_state *sm;
 665         struct sm_state *poss;
 666
 667         FOR_EACH_MY_SM(size_id, __get_cur_stree(), sm) {
 668                 if (sm->state != &merged)
 669                         continue;
 670                 /*
 671                  * screw it.  let's just assume that if one caller passes the
 672                  * size then they all do.
 673                  */
 674                 FOR_EACH_PTR(sm->possible, poss) {
 675                         if (poss->state != &merged &&
 676                             poss->state != &undefined) {
 677                                 add_ptr_list(&slist, poss);
 678                                 break;
 679                         }
 680                 } END_FOR_EACH_PTR(poss);
 681         } END_FOR_EACH_SM(sm);
 682
 683         FOR_EACH_PTR(slist, sm) {
 684                 set_state(size_id, sm->name, sm->sym, sm->state);
 685         } END_FOR_EACH_PTR(sm);
 686
 687         free_slist(&slist);
 688 }
 689
 690 static void set_used(struct expression *expr)
 691 {
 692         struct expression *parent;
 693         struct expression *array;
 694         struct expression *offset;
 695         struct sm_state *tmp;
 696         int limit_type;
 697
 698         if (expr->op != SPECIAL_INCREMENT)
 699                 return;
 700
 701         limit_type = USED_LAST;
 702         if (expr->type == EXPR_POSTOP)
 703                 limit_type = USED_COUNT;
 704
 705         parent = expr_get_parent_expr(expr);
 706         if (!parent || parent->type != EXPR_BINOP)
 707                 return;
 708         parent = expr_get_parent_expr(parent);
 709         if (!parent || !is_array(parent))
 710                 return;
 711
 712         array = get_array_base(parent);
 713         offset = get_array_offset(parent);
 714         if (offset != expr)
 715                 return;
 716
 717         tmp = set_state_expr(size_id, array, alloc_compare_size(limit_type, offset->unop));
 718         if (!tmp)
 719                 return;
 720         set_state_expr(link_id, offset->unop, alloc_state_expr(array));
 721 }
 722
 723 static int match_assign_array(struct expression *expr)
 724 {
 725         // FIXME: implement
 726         return 0;
 727 }
 728
 729 static int match_assign_size(struct expression *expr)
 730 {
 731         struct expression *right, *size, *array;
 732         struct smatch_state *state;
 733         struct sm_state *tmp;
 734         int limit_type;
 735
 736         right = expr->right;
 737         size = right;
 738         if (size->type == EXPR_BINOP)
 739                 size = size->left;
 740
 741         array = get_array_variable(size);
 742         if (!array)
 743                 return 0;
 744         state = get_state_expr(size_id, array);
 745         if (!state || !state->data)
 746                 return 0;
 747
 748         limit_type = state_to_limit(state);
 749         if (limit_type < 0)
 750                 return 0;
 751
 752         if (right->type == EXPR_BINOP && !match_size_binop(size, right, &limit_type))
 753                 return 0;
 754
 755         tmp = set_state_expr(size_id, array, alloc_compare_size(limit_type, expr->left));
 756         if (!tmp)
 757                 return 0;
 758         set_state_expr(link_id, expr->left, alloc_state_expr(array));
 759         return 1;
 760 }
 761
 762 static void match_assign(struct expression *expr)
 763 {
 764         if (expr->op != '=')
 765                 return;
 766
 767         if (match_assign_array(expr))
 768                 return;
 769         match_assign_size(expr);
 770 }
 771
 772 static void match_copy(const char *fn, struct expression *expr, void *unused)
 773 {
 774         struct expression *src, *size;
 775         int src_param, size_param;
 776
 777         src = get_argument_from_call_expr(expr->args, 1);
 778         size = get_argument_from_call_expr(expr->args, 2);
 779         src = strip_expr(src);
 780         size = strip_expr(size);
 781         if (!src || !size)
 782                 return;
 783         if (src->type != EXPR_SYMBOL || size->type != EXPR_SYMBOL)
 784                 return;
 785
 786         src_param = get_param_num_from_sym(src->symbol);
 787         size_param = get_param_num_from_sym(size->symbol);
 788         if (src_param < 0 || size_param < 0)
 789                 return;
 790
 791         sql_insert_cache(call_implies, "'%s', '%s', 0, %d, %d, %d, '==$%d', '%d'",
 792                          get_base_file(), get_function(), fn_static(),
 793                          BYTE_COUNT, src_param, size_param, BYTE_COUNT);
 794 }
 795
 796 void register_buf_comparison(int id)
 797 {
 798         int i;
 799
 800         size_id = id;
 801
 802         set_dynamic_states(size_id);
 803
 804         add_unmatched_state_hook(size_id, &unmatched_state);
 805
 806         add_allocation_function("malloc", &match_alloc, 0);
 807         add_allocation_function("memdup", &match_alloc, 1);
 808         add_allocation_function("realloc", &match_alloc, 1);
 809         if (option_project == PROJ_KERNEL) {
 810                 add_allocation_function("kmalloc", &match_alloc, 0);
 811                 add_allocation_function("kzalloc", &match_alloc, 0);
 812                 add_allocation_function("vmalloc", &match_alloc, 0);
 813                 add_allocation_function("__vmalloc", &match_alloc, 0);
 814                 add_allocation_function("sock_kmalloc", &match_alloc, 1);
 815                 add_allocation_function("kmemdup", &match_alloc, 1);
 816                 add_allocation_function("kmemdup_user", &match_alloc, 1);
 817                 add_allocation_function("dma_alloc_attrs", &match_alloc, 1);
 818                 add_allocation_function("pci_alloc_consistent", &match_alloc, 1);
 819                 add_allocation_function("pci_alloc_coherent", &match_alloc, 1);
 820                 add_allocation_function("devm_kmalloc", &match_alloc, 1);
 821                 add_allocation_function("devm_kzalloc", &match_alloc, 1);
 822                 add_allocation_function("kcalloc", &match_calloc, 0);
 823                 add_allocation_function("devm_kcalloc", &match_calloc, 1);
 824                 add_allocation_function("kmalloc_array", &match_calloc, 0);
 825                 add_allocation_function("krealloc", &match_alloc, 1);
 826
 827                 add_function_hook("copy_from_user", &match_copy, NULL);
 828                 add_function_hook("__copy_from_user", &match_copy, NULL);
 829         }
 830
 831         add_hook(&array_check, OP_HOOK);
 832         add_hook(&array_check_data_info, OP_HOOK);
 833         add_hook(&set_used, OP_HOOK);
 834
 835         add_hook(&match_call, FUNCTION_CALL_HOOK);
 836         add_hook(&munge_start_states, AFTER_DEF_HOOK);
 837
 838         add_hook(&match_assign, ASSIGNMENT_HOOK);
 839
 840         for (i = BYTE_COUNT; i <= USED_COUNT; i++) {
 841                 select_call_implies_hook(i, &set_implied);
 842                 select_caller_info_hook(set_param_compare, i);
 843                 select_return_implies_hook(i, &set_implied);
 844         }
 845 }
 846
 847 void register_buf_comparison_links(int id)
 848 {
 849         link_id = id;
 850         set_dynamic_states(link_id);
 851         add_merge_hook(link_id, &merge_links);
 852         add_modification_hook(link_id, &match_link_modify);
 853 }