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 struct expression *ignore_link_mod;
  60 static void match_link_modify(struct sm_state *sm, struct expression *mod_expr)
  61 {
  62         struct expression *expr;
  63         struct sm_state *tmp;
  64
  65         if (mod_expr == ignore_link_mod)
  66                 return;
  67         ignore_link_mod = NULL;
  68
  69         expr = sm->state->data;
  70         if (expr) {
  71                 set_state_expr(size_id, expr, &undefined);
  72                 set_state(link_id, sm->name, sm->sym, &undefined);
  73                 return;
  74         }
  75
  76         FOR_EACH_PTR(sm->possible, tmp) {
  77                 expr = tmp->state->data;
  78                 if (expr)
  79                         set_state_expr(size_id, expr, &undefined);
  80         } END_FOR_EACH_PTR(tmp);
  81         set_state(link_id, sm->name, sm->sym, &undefined);
  82 }
  83
  84 static void add_link(struct expression *size, struct expression *buf, struct expression *mod_expr)
  85 {
  86         ignore_link_mod = mod_expr;
  87         set_state_expr(link_id, size, alloc_state_expr(buf));
  88 }
  89
  90 static const char *limit_map[] = {
  91         "byte_count",
  92         "elem_count",
  93         "elem_last",
  94         "used_count",
  95         "used_last",
  96 };
  97
  98 int state_to_limit(struct smatch_state *state)
  99 {
 100         int i;
 101
 102         if (!state || !state->data)
 103                 return -1;
 104
 105         for (i = 0; i < ARRAY_SIZE(limit_map); i++) {
 106                 if (strncmp(state->name, limit_map[i], strlen(limit_map[i])) == 0)
 107                         return i + BYTE_COUNT;
 108         }
 109
 110         return -1;
 111 }
 112
 113 const char *limit_type_str(unsigned int limit_type)
 114 {
 115         if (limit_type - BYTE_COUNT >= ARRAY_SIZE(limit_map)) {
 116                 sm_msg("internal: wrong size type %u", limit_type);
 117                 return "unknown";
 118         }
 119
 120         return limit_map[limit_type - BYTE_COUNT];
 121 }
 122
 123 static struct smatch_state *alloc_compare_size(int limit_type, struct expression *expr)
 124 {
 125         struct smatch_state *state;
 126         char *name;
 127         char buf[256];
 128
 129         state = __alloc_smatch_state(0);
 130         expr = strip_expr(expr);
 131         name = expr_to_str(expr);
 132         snprintf(buf, sizeof(buf), "%s %s", limit_type_str(limit_type), name);
 133         state->name = alloc_sname(buf);
 134         free_string(name);
 135         state->data = expr;
 136         return state;
 137 }
 138
 139 static int bytes_per_element(struct expression *expr)
 140 {
 141         struct symbol *type;
 142
 143         type = get_type(expr);
 144         if (!type)
 145                 return 0;
 146
 147         if (type->type != SYM_PTR && type->type != SYM_ARRAY)
 148                 return 0;
 149
 150         type = get_base_type(type);
 151         return type_bytes(type);
 152 }
 153
 154 static void db_save_type_links(struct expression *array, int type_limit, struct expression *size)
 155 {
 156         const char *array_name;
 157
 158         array_name = get_data_info_name(array);
 159         if (!array_name)
 160                 array_name = "";
 161         sql_insert_data_info(size, type_limit, array_name);
 162 }
 163
 164 static void match_alloc_helper(struct expression *pointer, struct expression *size, struct expression *mod_expr)
 165 {
 166         struct smatch_state *state;
 167         struct expression *tmp;
 168         struct sm_state *sm;
 169         int limit_type = BYTE_COUNT;
 170         sval_t sval;
 171
 172         pointer = strip_expr(pointer);
 173         size = strip_expr(size);
 174         if (!size || !pointer)
 175                 return;
 176
 177         tmp = get_assigned_expr_recurse(size);
 178         if (tmp && tmp->type == EXPR_BINOP)
 179                 size = strip_expr(tmp);
 180
 181         if (size->type == EXPR_BINOP && size->op == '*') {
 182                 struct expression *mult_left, *mult_right;
 183
 184                 mult_left = strip_expr(size->left);
 185                 mult_right = strip_expr(size->right);
 186
 187                 if (get_implied_value(mult_left, &sval) &&
 188                     sval.value == bytes_per_element(pointer))
 189                         size = mult_right;
 190                 else if (get_implied_value(mult_right, &sval) &&
 191                     sval.value == bytes_per_element(pointer))
 192                         size = mult_left;
 193                 else
 194                         return;
 195                 limit_type = ELEM_COUNT;
 196         }
 197
 198         /* Only save links to variables, not fixed sizes */
 199         if (get_value(size, &sval))
 200                 return;
 201
 202         if (size->type == EXPR_BINOP && size->op == '+' &&
 203             get_value(size->right, &sval) && sval.value == 1) {
 204                 size = size->left;
 205                 limit_type = ELEM_LAST;
 206         }
 207
 208         db_save_type_links(pointer, limit_type, size);
 209         state = alloc_compare_size(limit_type, size);
 210         sm = set_state_expr(size_id, pointer, state);
 211         if (!sm)
 212                 return;
 213         add_link(size, pointer, mod_expr);
 214 }
 215
 216 static struct expression *get_struct_size_count(struct expression *expr)
 217 {
 218         /*
 219          * There are three ways that struct_size() can be implemented but
 220          * we can ignore build time constants so really there are two ways we
 221          * care about:
 222          * 1) Using __ab_c_size()
 223          * 2) Using size_add(struct_size, size_mul(elem_count, elem_size))
 224          *
 225          */
 226
 227         if (expr->type != EXPR_CALL)
 228                 return NULL;
 229
 230         if (sym_name_is("__ab_c_size", expr->fn))
 231                 return get_argument_from_call_expr(expr->args, 0);
 232
 233         if (!sym_name_is("size_add", expr->fn))
 234                 return NULL;
 235         expr = get_argument_from_call_expr(expr->args, 1);
 236         expr = strip_expr(expr);
 237         if (!expr || expr->type != EXPR_CALL ||
 238             !sym_name_is("size_mul", expr->fn))
 239                 return NULL;
 240
 241         return get_argument_from_call_expr(expr->args, 0);
 242 }
 243
 244 static struct expression *get_variable_struct_member(struct expression *expr)
 245 {
 246         struct symbol *type, *last_member;
 247         sval_t sval;
 248
 249         /*
 250          * This is a hack.  It should look at how the size is calculated instead
 251          * of just assuming that it's the last element.  However, ugly hacks are
 252          * easier to write.
 253          */
 254
 255         type = get_type(expr);
 256         if (!type || type->type != SYM_PTR)
 257                 return NULL;
 258         type = get_real_base_type(type);
 259         if (!type || type->type != SYM_STRUCT)
 260                 return NULL;
 261         last_member = last_ptr_list((struct ptr_list *)type->symbol_list);
 262         if (!last_member || !last_member->ident)
 263                 return NULL;
 264         type = get_real_base_type(last_member);
 265         if (!type || type->type != SYM_ARRAY)
 266                 return NULL;
 267         /* Is non-zero array size */
 268         if (type->array_size) {
 269                 if (!get_implied_value(type->array_size, &sval) ||
 270                     sval.value != 0)
 271                         return NULL;
 272         }
 273
 274         return member_expression(expr, '*', last_member->ident);
 275 }
 276
 277 static void match_struct_size_helper(struct expression *pointer, struct expression *size, struct expression *mod_expr)
 278 {
 279         struct expression *tmp, *count, *member;
 280         struct smatch_state *state;
 281         struct sm_state *sm;
 282
 283         if (option_project != PROJ_KERNEL)
 284                 return;
 285
 286         pointer = strip_expr(pointer);
 287         tmp = get_assigned_expr_recurse(size);
 288         if (tmp)
 289                 size = tmp;
 290         size = strip_expr(size);
 291         if (!size || !pointer)
 292                 return;
 293         count = get_struct_size_count(size);
 294         if (!count)
 295                 return;
 296         member = get_variable_struct_member(pointer);
 297
 298         db_save_type_links(member, ELEM_COUNT, count);
 299         state = alloc_compare_size(ELEM_COUNT, count);
 300         sm = set_state_expr(size_id, member, state);
 301         if (!sm)
 302                 return;
 303         add_link(count, member, mod_expr);
 304 }
 305
 306 static void match_alloc(const char *fn, struct expression *expr, void *_size_arg)
 307 {
 308         int size_arg = PTR_INT(_size_arg);
 309         struct expression *pointer, *call, *arg;
 310
 311         pointer = strip_expr(expr->left);
 312         call = strip_expr(expr->right);
 313         arg = get_argument_from_call_expr(call->args, size_arg);
 314         match_alloc_helper(pointer, arg, expr);
 315         match_struct_size_helper(pointer, arg, expr);
 316 }
 317
 318 static void match_calloc(const char *fn, struct expression *expr, void *_start_arg)
 319 {
 320         struct smatch_state *state;
 321         int start_arg = PTR_INT(_start_arg);
 322         struct expression *pointer, *call, *arg;
 323         struct sm_state *tmp;
 324         int limit_type = ELEM_COUNT;
 325         sval_t sval;
 326
 327         pointer = strip_expr(expr->left);
 328         call = strip_expr(expr->right);
 329         arg = get_argument_from_call_expr(call->args, start_arg);
 330         if (get_implied_value(arg, &sval) &&
 331             sval.value == bytes_per_element(pointer))
 332                 arg = get_argument_from_call_expr(call->args, start_arg + 1);
 333
 334         if (arg->type == EXPR_BINOP && arg->op == '+' &&
 335             get_value(arg->right, &sval) && sval.value == 1) {
 336                 arg = arg->left;
 337                 limit_type = ELEM_LAST;
 338         }
 339
 340         state = alloc_compare_size(limit_type, arg);
 341         db_save_type_links(pointer, limit_type, arg);
 342         tmp = set_state_expr(size_id, pointer, state);
 343         if (!tmp)
 344                 return;
 345         add_link(arg, pointer, expr);
 346 }
 347
 348 static struct expression *get_size_variable_from_binop(struct expression *expr, int *limit_type)
 349 {
 350         struct smatch_state *state;
 351         struct expression *ret;
 352         struct symbol *type;
 353         sval_t orig_fixed;
 354         int offset_bytes;
 355         sval_t offset;
 356
 357         if (!get_value(expr->right, &offset))
 358                 return NULL;
 359         state = get_state_expr(size_id, expr->left);
 360         if (!state || !state->data)
 361                 return NULL;
 362
 363         type = get_type(expr->left);
 364         if (!type_is_ptr(type))
 365                 return NULL;
 366         type = get_real_base_type(type);
 367         if (!type_bytes(type))
 368                 return NULL;
 369         offset_bytes = offset.value * type_bytes(type);
 370
 371         ret = state->data;
 372         if (ret->type != EXPR_BINOP || ret->op != '+')
 373                 return NULL;
 374
 375         *limit_type = state_to_limit(state);
 376
 377         if (get_value(ret->left, &orig_fixed) && orig_fixed.value == offset_bytes)
 378                 return ret->right;
 379         if (get_value(ret->right, &orig_fixed) && orig_fixed.value == offset_bytes)
 380                 return ret->left;
 381
 382         return NULL;
 383 }
 384
 385 struct expression *get_size_variable(struct expression *buf, int *limit_type)
 386 {
 387         struct smatch_state *state;
 388         struct expression *ret;
 389
 390         buf = strip_expr(buf);
 391         if (!buf)
 392                 return NULL;
 393         if (buf->type == EXPR_BINOP && buf->op == '+') {
 394                 ret = get_size_variable_from_binop(buf, limit_type);
 395                 if (ret)
 396                         return ret;
 397         }
 398
 399         state = get_state_expr(size_id, buf);
 400         if (!state)
 401                 return NULL;
 402         *limit_type = state_to_limit(state);
 403         return state->data;
 404 }
 405
 406 struct expression *get_array_variable(struct expression *size)
 407 {
 408         struct smatch_state *state;
 409
 410         state = get_state_expr(link_id, size);
 411         if (state)
 412                 return state->data;
 413         return NULL;
 414 }
 415
 416 static void array_check(struct expression *expr)
 417 {
 418         struct expression *array;
 419         struct expression *size;
 420         struct expression *offset;
 421         char *array_str, *offset_str;
 422         int limit_type;
 423
 424         expr = strip_expr(expr);
 425         if (!is_array(expr))
 426                 return;
 427
 428         array = get_array_base(expr);
 429         size = get_size_variable(array, &limit_type);
 430         if (!size)
 431                 return;
 432         if (limit_type != ELEM_COUNT)
 433                 return;
 434         offset = get_array_offset(expr);
 435         if (!possible_comparison(size, SPECIAL_EQUAL, offset))
 436                 return;
 437         if (getting_address(expr))
 438                 return;
 439
 440         array_str = expr_to_str(array);
 441         offset_str = expr_to_str(offset);
 442         sm_warning("potentially one past the end of array '%s[%s]'", array_str, offset_str);
 443         free_string(array_str);
 444         free_string(offset_str);
 445 }
 446
 447 struct db_info {
 448         char *name;
 449         int ret;
 450 };
 451
 452 static int db_limitter_callback(void *_info, int argc, char **argv, char **azColName)
 453 {
 454         struct db_info *info = _info;
 455
 456         /*
 457          * If possible the limitters are tied to the struct they limit.  If we
 458          * aren't sure which struct they limit then we use them as limitters for
 459          * everything.
 460          */
 461         if (!info->name || argv[0][0] == '\0' || strcmp(info->name, argv[0]) == 0)
 462                 info->ret = 1;
 463         return 0;
 464 }
 465
 466 static char *vsl_to_data_info_name(const char *name, struct var_sym_list *vsl)
 467 {
 468         struct var_sym *vs;
 469         struct symbol *type;
 470         static char buf[80];
 471         const char *p;
 472
 473         if (ptr_list_size((struct ptr_list *)vsl) != 1)
 474                 return NULL;
 475         vs = first_ptr_list((struct ptr_list *)vsl);
 476
 477         type = get_real_base_type(vs->sym);
 478         if (!type || type->type != SYM_PTR)
 479                 goto top_level_name;
 480         type = get_real_base_type(type);
 481         if (!type || type->type != SYM_STRUCT)
 482                 goto top_level_name;
 483         if (!type->ident)
 484                 goto top_level_name;
 485
 486         p = name;
 487         while ((name = strstr(p, "->")))
 488                 p = name + 2;
 489
 490         snprintf(buf, sizeof(buf),"(struct %s)->%s", type->ident->name, p);
 491         return alloc_sname(buf);
 492
 493 top_level_name:
 494         if (!(vs->sym->ctype.modifiers & MOD_TOPLEVEL))
 495                 return NULL;
 496         if (vs->sym->ctype.modifiers & MOD_STATIC)
 497                 snprintf(buf, sizeof(buf),"static %s", name);
 498         else
 499                 snprintf(buf, sizeof(buf),"global %s", name);
 500         return alloc_sname(buf);
 501 }
 502
 503 int db_var_is_array_limit(struct expression *array, const char *name, struct var_sym_list *vsl)
 504 {
 505         char *size_name;
 506         char *array_name = get_data_info_name(array);
 507         struct db_info db_info = {.name = array_name,};
 508
 509         size_name = vsl_to_data_info_name(name, vsl);
 510         if (!size_name)
 511                 return 0;
 512
 513         run_sql(db_limitter_callback, &db_info,
 514                 "select value from data_info where type = %d and data = '%s';",
 515                 ARRAY_LEN, size_name);
 516
 517         return db_info.ret;
 518 }
 519
 520 int buf_comparison_index_ok(struct expression *expr)
 521 {
 522         struct expression *array;
 523         struct expression *size;
 524         struct expression *offset;
 525         int limit_type;
 526         int comparison;
 527
 528         array = get_array_base(expr);
 529         size = get_size_variable(array, &limit_type);
 530         if (!size)
 531                 return 0;
 532         offset = get_array_offset(expr);
 533         comparison = get_comparison(offset, size);
 534         if (!comparison)
 535                 return 0;
 536
 537         if ((limit_type == ELEM_COUNT || limit_type == ELEM_LAST) &&
 538             (comparison == '<' || comparison == SPECIAL_UNSIGNED_LT))
 539                 return 1;
 540
 541         if (limit_type == BYTE_COUNT && bytes_per_element(array) == 1 &&
 542             (comparison == '<' || comparison == SPECIAL_UNSIGNED_LT))
 543                 return 1;
 544
 545         if (limit_type == ELEM_LAST &&
 546             (comparison == SPECIAL_LTE ||
 547              comparison == SPECIAL_UNSIGNED_LTE ||
 548              comparison == SPECIAL_EQUAL))
 549                 return 1;
 550
 551         return 0;
 552 }
 553
 554 bool buf_comp_has_bytes(struct expression *buf, struct expression *var)
 555 {
 556         struct expression *size;
 557         int limit_type;
 558         int comparison;
 559
 560         if (buf_comp2_has_bytes(buf, var))
 561                 return true;
 562
 563         size = get_size_variable(buf, &limit_type);
 564         if (!size)
 565                 return false;
 566         comparison = get_comparison(size, var);
 567         if (comparison == UNKNOWN_COMPARISON ||
 568             comparison == IMPOSSIBLE_COMPARISON)
 569                 return false;
 570
 571         if (show_special(comparison)[0] == '<' ||
 572             show_special(comparison)[0] == '=')
 573                 return true;
 574
 575         return false;
 576 }
 577
 578 static int known_access_ok_numbers(struct expression *expr)
 579 {
 580         struct expression *array;
 581         struct expression *offset;
 582         sval_t max;
 583         int size;
 584
 585         array = get_array_base(expr);
 586         offset = get_array_offset(expr);
 587
 588         size = get_array_size(array);
 589         if (size <= 0)
 590                 return 0;
 591
 592         get_absolute_max(offset, &max);
 593         if (max.uvalue < size)
 594                 return 1;
 595         return 0;
 596 }
 597
 598 static void array_check_data_info(struct expression *expr)
 599 {
 600         struct expression *array;
 601         struct expression *offset;
 602         struct state_list *slist;
 603         struct sm_state *sm;
 604         struct compare_data *comp;
 605         char *offset_name;
 606         const char *equal_name = NULL;
 607
 608         expr = strip_expr(expr);
 609         if (!is_array(expr))
 610                 return;
 611
 612         if (known_access_ok_numbers(expr))
 613                 return;
 614         if (buf_comparison_index_ok(expr))
 615                 return;
 616
 617         array = get_array_base(expr);
 618         offset = get_array_offset(expr);
 619         offset_name = expr_to_var(offset);
 620         if (!offset_name)
 621                 return;
 622         slist = get_all_possible_equal_comparisons(offset);
 623         if (!slist)
 624                 goto free;
 625
 626         FOR_EACH_PTR(slist, sm) {
 627                 comp = sm->state->data;
 628                 if (strcmp(comp->left_var, offset_name) == 0) {
 629                         if (db_var_is_array_limit(array, comp->right_var, comp->right_vsl)) {
 630                                 equal_name = comp->right_var;
 631                                 break;
 632                         }
 633                 } else if (strcmp(comp->right_var, offset_name) == 0) {
 634                         if (db_var_is_array_limit(array, comp->left_var, comp->left_vsl)) {
 635                                 equal_name = comp->left_var;
 636                                 break;
 637                         }
 638                 }
 639         } END_FOR_EACH_PTR(sm);
 640
 641         if (equal_name) {
 642                 char *array_name = expr_to_str(array);
 643
 644                 sm_warning("potential off by one '%s[]' limit '%s'", array_name, equal_name);
 645                 free_string(array_name);
 646         }
 647
 648 free:
 649         free_slist(&slist);
 650         free_string(offset_name);
 651 }
 652
 653 static void add_allocation_function(const char *func, void *call_back, int param)
 654 {
 655         add_function_assign_hook(func, call_back, INT_PTR(param));
 656 }
 657
 658 static int is_sizeof(struct expression *expr)
 659 {
 660         const char *name;
 661
 662         if (expr->type == EXPR_SIZEOF)
 663                 return 1;
 664         name = pos_ident(expr->pos);
 665         if (name && strcmp(name, "sizeof") == 0)
 666                 return 1;
 667         return 0;
 668 }
 669
 670 static int match_size_binop(struct expression *size, struct expression *expr, int *limit_type)
 671 {
 672         int orig_type = *limit_type;
 673         struct expression *left;
 674         sval_t sval;
 675
 676         left = expr->left;
 677         if (!expr_equiv(size, left))
 678                 return 0;
 679
 680         if (expr->op == '-' &&
 681             get_value(expr->right, &sval) &&
 682             sval.value == 1 &&
 683             orig_type == ELEM_COUNT) {
 684                 *limit_type = ELEM_LAST;
 685                 return 1;
 686         }
 687
 688         if (expr->op == '+' &&
 689             get_value(expr->right, &sval) &&
 690             sval.value == 1 &&
 691             orig_type == ELEM_LAST) {
 692                 *limit_type = ELEM_COUNT;
 693                 return 1;
 694         }
 695
 696         if (expr->op == '*' &&
 697             is_sizeof(expr->right) &&
 698             orig_type == ELEM_COUNT) {
 699                 *limit_type = BYTE_COUNT;
 700                 return 1;
 701         }
 702
 703         if (expr->op == '/' &&
 704             is_sizeof(expr->right) &&
 705             orig_type == BYTE_COUNT) {
 706                 *limit_type = ELEM_COUNT;
 707                 return 1;
 708         }
 709
 710         return 0;
 711 }
 712
 713 static char *buf_size_param_comparison(struct expression *array, struct expression_list *args, int *limit_type)
 714 {
 715         struct expression *tmp, *arg;
 716         struct expression *size;
 717         static char buf[32];
 718         int i;
 719
 720         size = get_size_variable(array, limit_type);
 721         if (!size)
 722                 return NULL;
 723
 724         if (*limit_type == USED_LAST)
 725                 *limit_type = ELEM_LAST;
 726         if (*limit_type == USED_COUNT)
 727                 *limit_type = ELEM_COUNT;
 728
 729         i = -1;
 730         FOR_EACH_PTR(args, tmp) {
 731                 i++;
 732                 arg = tmp;
 733                 if (arg == array)
 734                         continue;
 735                 if (expr_equiv(arg, size) ||
 736                     (arg->type == EXPR_BINOP &&
 737                      match_size_binop(size, arg, limit_type))) {
 738                         snprintf(buf, sizeof(buf), "==$%d", i);
 739                         return buf;
 740                 }
 741         } END_FOR_EACH_PTR(tmp);
 742
 743         return NULL;
 744 }
 745
 746 static void match_call(struct expression *call)
 747 {
 748         struct expression *arg;
 749         char *compare;
 750         int param;
 751         char buf[5];
 752         int limit_type;
 753
 754         param = -1;
 755         FOR_EACH_PTR(call->args, arg) {
 756                 param++;
 757                 if (!is_pointer(arg))
 758                         continue;
 759                 compare = buf_size_param_comparison(arg, call->args, &limit_type);
 760                 if (!compare)
 761                         continue;
 762                 snprintf(buf, sizeof(buf), "%d", limit_type);
 763                 sql_insert_caller_info(call, limit_type, param, compare, buf);
 764         } END_FOR_EACH_PTR(arg);
 765 }
 766
 767 static int get_param(int param, char **name, struct symbol **sym)
 768 {
 769         struct symbol *arg;
 770         int i;
 771
 772         i = 0;
 773         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 774                 /*
 775                  * this is a temporary hack to work around a bug (I think in sparse?)
 776                  * 2.6.37-rc1:fs/reiserfs/journal.o
 777                  * If there is a function definition without parameter name found
 778                  * after a function implementation then it causes a crash.
 779                  * int foo() {}
 780                  * int bar(char *);
 781                  */
 782                 if (arg->ident->name < (char *)100)
 783                         continue;
 784                 if (i == param) {
 785                         *name = arg->ident->name;
 786                         *sym = arg;
 787                         return TRUE;
 788                 }
 789                 i++;
 790         } END_FOR_EACH_PTR(arg);
 791
 792         return FALSE;
 793 }
 794
 795 static void set_param_compare(const char *array_name, struct symbol *array_sym, char *key, char *value)
 796 {
 797         struct smatch_state *state;
 798         struct expression *array_expr;
 799         struct expression *size_expr;
 800         struct symbol *size_sym;
 801         char *size_name;
 802         long param;
 803         struct sm_state *tmp;
 804         int limit_type;
 805
 806         if (strncmp(key, "==$", 3) != 0)
 807                 return;
 808         param = strtol(key + 3, NULL, 10);
 809         if (!get_param(param, &size_name, &size_sym))
 810                 return;
 811         array_expr = symbol_expression(array_sym);
 812         size_expr = symbol_expression(size_sym);
 813         limit_type = strtol(value, NULL, 10);
 814
 815         state = alloc_compare_size(limit_type, size_expr);
 816         tmp = set_state_expr(size_id, array_expr, state);
 817         if (!tmp)
 818                 return;
 819         add_link(size_expr, array_expr, NULL);
 820 }
 821
 822 static void set_implied(struct expression *call, struct expression *array_expr, char *key, char *value)
 823 {
 824         struct expression *size_expr;
 825         struct symbol *size_sym;
 826         char *size_name;
 827         long param;
 828         struct sm_state *tmp;
 829         int limit_type;
 830
 831         if (strncmp(key, "==$", 3) != 0)
 832                 return;
 833         param = strtol(key + 3, NULL, 10);
 834         if (!get_param(param, &size_name, &size_sym))
 835                 return;
 836         size_expr = symbol_expression(size_sym);
 837
 838         limit_type = strtol(value, NULL, 10);
 839         tmp = set_state_expr(size_id, array_expr, alloc_compare_size(limit_type, size_expr));
 840         if (!tmp)
 841                 return;
 842         add_link(size_expr, array_expr, call);
 843 }
 844
 845 static void munge_start_states(struct statement *stmt)
 846 {
 847         struct state_list *slist = NULL;
 848         struct sm_state *sm;
 849         struct sm_state *poss;
 850
 851         FOR_EACH_MY_SM(size_id, __get_cur_stree(), sm) {
 852                 if (sm->state != &merged)
 853                         continue;
 854                 /*
 855                  * screw it.  let's just assume that if one caller passes the
 856                  * size then they all do.
 857                  */
 858                 FOR_EACH_PTR(sm->possible, poss) {
 859                         if (poss->state != &merged &&
 860                             poss->state != &undefined) {
 861                                 add_ptr_list(&slist, poss);
 862                                 break;
 863                         }
 864                 } END_FOR_EACH_PTR(poss);
 865         } END_FOR_EACH_SM(sm);
 866
 867         FOR_EACH_PTR(slist, sm) {
 868                 set_state(size_id, sm->name, sm->sym, sm->state);
 869         } END_FOR_EACH_PTR(sm);
 870
 871         free_slist(&slist);
 872 }
 873
 874 static void set_used(struct expression *expr)
 875 {
 876         struct expression *parent;
 877         struct expression *array;
 878         struct expression *offset;
 879         struct sm_state *tmp;
 880         int limit_type;
 881
 882         if (expr->op != SPECIAL_INCREMENT)
 883                 return;
 884
 885         limit_type = USED_LAST;
 886         if (expr->type == EXPR_POSTOP)
 887                 limit_type = USED_COUNT;
 888
 889         parent = expr_get_parent_expr(expr);
 890         if (!parent || parent->type != EXPR_BINOP)
 891                 return;
 892         parent = expr_get_parent_expr(parent);
 893         if (!parent || !is_array(parent))
 894                 return;
 895
 896         array = get_array_base(parent);
 897         offset = get_array_offset(parent);
 898         if (offset != expr)
 899                 return;
 900
 901         tmp = set_state_expr(size_id, array, alloc_compare_size(limit_type, offset->unop));
 902         if (!tmp)
 903                 return;
 904         add_link(offset->unop, array, expr);
 905 }
 906
 907 static int match_assign_array(struct expression *expr)
 908 {
 909         // FIXME: implement
 910         return 0;
 911 }
 912
 913 static int match_assign_size(struct expression *expr)
 914 {
 915         struct expression *right, *size, *array;
 916         struct smatch_state *state;
 917         struct sm_state *tmp;
 918         int limit_type;
 919
 920         right = expr->right;
 921         size = right;
 922         if (size->type == EXPR_BINOP)
 923                 size = size->left;
 924
 925         array = get_array_variable(size);
 926         if (!array)
 927                 return 0;
 928         state = get_state_expr(size_id, array);
 929         if (!state || !state->data)
 930                 return 0;
 931
 932         limit_type = state_to_limit(state);
 933         if (limit_type < 0)
 934                 return 0;
 935
 936         if (right->type == EXPR_BINOP && !match_size_binop(size, right, &limit_type))
 937                 return 0;
 938
 939         tmp = set_state_expr(size_id, array, alloc_compare_size(limit_type, expr->left));
 940         if (!tmp)
 941                 return 0;
 942         add_link(expr->left, array, expr);
 943         return 1;
 944 }
 945
 946 static bool match_assign_smaller(struct expression *expr)
 947 {
 948         struct expression *array;
 949         int comparison;
 950         sval_t sval;
 951
 952         array = get_array_variable(expr->left);
 953         if (!array)
 954                 return false;
 955
 956         if (get_value(expr->right, &sval))
 957                 return false;
 958
 959         comparison = get_comparison(expr->left, expr->right);
 960         if (comparison == UNKNOWN_COMPARISON ||
 961             comparison == IMPOSSIBLE_COMPARISON)
 962                 return false;
 963
 964         /* This is assigning a smaller value to the variable than what it was. */
 965         if (show_special(comparison)[0] != '>')
 966                 return false;
 967
 968         /*
 969          * This module doesn't have a way to say that it's less than the limit
 970          * only that it *is* the limit.  So you might expect to set a state here
 971          * but there is already a state so all we can do is ignore the
 972          * assignment.
 973          */
 974         ignore_link_mod = expr;
 975         return true;
 976 }
 977
 978 static void match_assign(struct expression *expr)
 979 {
 980         if (expr->op != '=')
 981                 return;
 982
 983         if (is_fake_var_assign(expr))
 984                 return;
 985
 986         if (match_assign_array(expr))
 987                 return;
 988         if (match_assign_size(expr))
 989                 return;
 990         if (match_assign_smaller(expr))
 991                 return;
 992 }
 993
 994 static void match_copy(const char *fn, struct expression *expr, void *unused)
 995 {
 996         struct expression *src, *size;
 997         int src_param, size_param;
 998
 999         src = get_argument_from_call_expr(expr->args, 1);
1000         size = get_argument_from_call_expr(expr->args, 2);
1001         src = strip_expr(src);
1002         size = strip_expr(size);
1003         if (!src || !size)
1004                 return;
1005         if (src->type != EXPR_SYMBOL || size->type != EXPR_SYMBOL)
1006                 return;
1007
1008         src_param = get_param_num_from_sym(src->symbol);
1009         size_param = get_param_num_from_sym(size->symbol);
1010         if (src_param < 0 || size_param < 0)
1011                 return;
1012
1013         sql_insert_cache(call_implies, "'%s', '%s', 0, %d, %d, %d, '==$%d', '%d'",
1014                          get_base_file(), get_function(), fn_static(),
1015                          BYTE_COUNT, src_param, size_param, BYTE_COUNT);
1016 }
1017
1018 void register_buf_comparison(int id)
1019 {
1020         int i;
1021
1022         size_id = id;
1023
1024         set_dynamic_states(size_id);
1025
1026         add_unmatched_state_hook(size_id, &unmatched_state);
1027
1028         add_allocation_function("malloc", &match_alloc, 0);
1029         add_allocation_function("memdup", &match_alloc, 1);
1030         add_allocation_function("realloc", &match_alloc, 1);
1031         if (option_project == PROJ_KERNEL) {
1032                 add_allocation_function("kmalloc", &match_alloc, 0);
1033                 add_allocation_function("kzalloc", &match_alloc, 0);
1034                 add_allocation_function("vmalloc", &match_alloc, 0);
1035                 add_allocation_function("__vmalloc", &match_alloc, 0);
1036                 add_allocation_function("sock_kmalloc", &match_alloc, 1);
1037                 add_allocation_function("kmemdup", &match_alloc, 1);
1038                 add_allocation_function("memdup_user", &match_alloc, 1);
1039                 add_allocation_function("dma_alloc_attrs", &match_alloc, 1);
1040                 add_allocation_function("dma_alloc_coherent", &match_alloc, 1);
1041                 add_allocation_function("devm_kmalloc", &match_alloc, 1);
1042                 add_allocation_function("devm_kzalloc", &match_alloc, 1);
1043                 add_allocation_function("kcalloc", &match_calloc, 0);
1044                 add_allocation_function("devm_kcalloc", &match_calloc, 1);
1045                 add_allocation_function("kmalloc_array", &match_calloc, 0);
1046                 add_allocation_function("krealloc", &match_alloc, 1);
1047
1048                 add_function_hook("copy_from_user", &match_copy, NULL);
1049                 add_function_hook("__copy_from_user", &match_copy, NULL);
1050         }
1051
1052         add_hook(&array_check, OP_HOOK);
1053         add_hook(&array_check_data_info, OP_HOOK);
1054         add_hook(&set_used, OP_HOOK);
1055
1056         add_hook(&match_call, FUNCTION_CALL_HOOK);
1057         add_hook(&munge_start_states, AFTER_DEF_HOOK);
1058
1059         add_hook(&match_assign, ASSIGNMENT_HOOK);
1060
1061         for (i = BYTE_COUNT; i <= USED_COUNT; i++) {
1062                 select_call_implies_hook(i, &set_implied);
1063                 select_caller_info_hook(set_param_compare, i);
1064                 select_return_implies_hook(i, &set_implied);
1065         }
1066 }
1067
1068 void register_buf_comparison_links(int id)
1069 {
1070         link_id = id;
1071         set_dynamic_states(link_id);
1072         add_merge_hook(link_id, &merge_links);
1073         add_modification_hook_late(link_id, &match_link_modify);
1074 }