smatch_buf_size.c

   1 /*
   2  * smatch/smatch_buf_size.c
   3  *
   4  * Copyright (C) 2010 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include <stdlib.h>
  11 #include <errno.h>
  12 #include "parse.h"
  13 #include "smatch.h"
  14 #include "smatch_slist.h"
  15 #include "smatch_extra.h"
  16
  17 /*
  18  * This check has two smatch IDs.
  19  * my_size_id - used to store the size of arrays.
  20  * my_strlen_id - track the strlen() of buffers.
  21  */
  22
  23 static int my_size_id;
  24 static int my_strlen_id;
  25
  26 struct limiter {
  27         int buf_arg;
  28         int limit_arg;
  29 };
  30 static struct limiter b0_l2 = {0, 2};
  31
  32 static _Bool params_set[32];
  33
  34 static void set_undefined(struct sm_state *sm)
  35 {
  36         if (sm->state != &undefined)
  37                 set_state(sm->owner, sm->name, sm->sym, &undefined);
  38 }
  39
  40 void set_param_buf_size(const char *name, struct symbol *sym, char *key, char *value)
  41 {
  42         char fullname[256];
  43         unsigned int size;
  44
  45         if (strncmp(key, "$$", 2))
  46                 return;
  47
  48         snprintf(fullname, 256, "%s%s", name, key + 2);
  49
  50         errno = 0;
  51         size = strtoul(value, NULL, 10);
  52         if (errno)
  53                 return;
  54
  55         set_state(my_size_id, fullname, sym, alloc_state_num(size));
  56 }
  57
  58 static int get_initializer_size(struct expression *expr)
  59 {
  60         switch (expr->type) {
  61         case EXPR_STRING:
  62                 return expr->string->length;
  63         case EXPR_INITIALIZER: {
  64                 struct expression *tmp;
  65                 int i = 0;
  66                 int max = 0;
  67
  68                 FOR_EACH_PTR(expr->expr_list, tmp) {
  69                         if (tmp->type == EXPR_INDEX && tmp->idx_to > max)
  70                                 max = tmp->idx_to;
  71                         i++;
  72                 } END_FOR_EACH_PTR(tmp);
  73                 if (max)
  74                         return max + 1;
  75                 return i;
  76         }
  77         case EXPR_SYMBOL:
  78                 return get_array_size(expr);
  79         }
  80         return 0;
  81 }
  82
  83 static float get_cast_ratio(struct expression *unstripped)
  84 {
  85         struct expression *start_expr;
  86         struct symbol *start_type;
  87         struct symbol *end_type;
  88         int start_bytes = 0;
  89         int end_bytes = 0;
  90
  91         start_expr = strip_expr(unstripped);
  92         start_type  =  get_type(start_expr);
  93         end_type = get_type(unstripped);
  94         if (!start_type || !end_type)
  95                 return 1;
  96
  97         if (start_type->type == SYM_PTR)
  98                 start_bytes = (get_base_type(start_type))->ctype.alignment;
  99         if (start_type->type == SYM_ARRAY)
 100                 start_bytes = (get_base_type(start_type))->bit_size / 8;
 101         if (end_type->type == SYM_PTR)
 102                 end_bytes = (get_base_type(end_type))->ctype.alignment;
 103         if (end_type->type == SYM_ARRAY)
 104                 end_bytes = (get_base_type(end_type))->bit_size / 8;
 105
 106         if (!start_bytes || !end_bytes)
 107                 return 1;
 108         return start_bytes / end_bytes;
 109 }
 110
 111 static int db_size;
 112 static int db_size_callback(void *unused, int argc, char **argv, char **azColName)
 113 {
 114         db_size = atoi(argv[0]);
 115         return 0;
 116 }
 117
 118 static int size_from_db(struct expression *expr)
 119 {
 120         char *name;
 121
 122         if (!option_spammy)
 123                 return 0;
 124
 125         name = get_member_name(expr);
 126         if (!name)
 127                 return 0;
 128
 129         db_size = 0;
 130         run_sql(db_size_callback, "select size from type_size where type = '%s'",
 131                         name);
 132         return db_size;
 133 }
 134
 135 static int get_real_array_size(struct expression *expr)
 136 {
 137         struct symbol *type;
 138         float cast_ratio;
 139         int ret;
 140
 141         type = get_type(expr);
 142         if (!type || type->type != SYM_ARRAY)
 143                 return 0;
 144
 145         cast_ratio = get_cast_ratio(expr);
 146
 147         ret = get_expression_value(type->array_size);
 148         /* Dynamically sized array are -1 in sparse */
 149         if (ret <= 0)
 150                 return 0;
 151         /* People put one element arrays on the end of structs */
 152         if (ret == 1)
 153                 return 0;
 154
 155         return ret * cast_ratio;
 156 }
 157
 158 int get_array_size(struct expression *expr)
 159 {
 160         struct symbol *tmp;
 161         struct smatch_state *state;
 162         int ret = 0;
 163         float cast_ratio;
 164         long long len;
 165
 166         if (expr->type == EXPR_STRING)
 167                 return expr->string->length;
 168
 169         ret = get_real_array_size(expr);
 170         if (ret)
 171                 return ret;
 172
 173         cast_ratio = get_cast_ratio(expr);
 174         expr = strip_expr(expr);
 175         tmp = get_type(expr);
 176         if (!tmp)
 177                 return 0;
 178
 179         state = get_state_expr(my_size_id, expr);
 180         if (state == &merged)
 181                 return 0;
 182         if (state && state->data) {
 183                 if (tmp->type == SYM_PTR)
 184                         tmp = get_base_type(tmp);
 185                 if (!tmp->ctype.alignment)
 186                         return 0;
 187                 ret = PTR_INT(state->data) / tmp->ctype.alignment;
 188                 return ret * cast_ratio;
 189         }
 190
 191         if (expr->type == EXPR_SYMBOL && expr->symbol->initializer) {
 192                 if (expr->symbol->initializer != expr) /* int a = a; */
 193                         return get_initializer_size(expr->symbol->initializer) * cast_ratio;
 194         }
 195
 196         state = get_state_expr(my_strlen_id, expr);
 197         if (!state || !state->data)
 198                 return 0;
 199         if (get_implied_max((struct expression *)state->data, &len))
 200                 return len + 1; /* add one because strlen doesn't include the NULL */
 201         return 0;
 202 }
 203
 204 int get_array_size_bytes(struct expression *expr)
 205 {
 206         struct symbol *tmp;
 207         int array_size;
 208         int element_size;
 209
 210         if (!expr)
 211                 return 0;
 212
 213         if (expr->type == EXPR_STRING)
 214                 return expr->string->length;
 215
 216         tmp = get_type(expr);
 217         if (!tmp)
 218                 return 0;
 219
 220         if (tmp->type == SYM_ARRAY) {
 221                 tmp = get_base_type(tmp);
 222                 element_size = tmp->bit_size / 8;
 223         } else if (tmp->type == SYM_PTR) {
 224                 tmp = get_base_type(tmp);
 225                 element_size = tmp->ctype.alignment;
 226         } else {
 227                 return 0;
 228         }
 229         array_size = get_array_size(expr);
 230         if (array_size)
 231                 return array_size * element_size;
 232
 233         return size_from_db(expr);
 234 }
 235
 236 static void match_strlen_condition(struct expression *expr)
 237 {
 238         struct expression *left;
 239         struct expression *right;
 240         struct expression *str = NULL;
 241         int strlen_left = 0;
 242         int strlen_right = 0;
 243         long long val;
 244         struct smatch_state *true_state = NULL;
 245         struct smatch_state *false_state = NULL;
 246
 247         if (expr->type != EXPR_COMPARE)
 248                 return;
 249         left = strip_expr(expr->left);
 250         right = strip_expr(expr->right);
 251
 252         if (left->type == EXPR_CALL && sym_name_is("strlen", left->fn)) {
 253                 str = get_argument_from_call_expr(left->args, 0);
 254                 strlen_left = 1;
 255         }
 256         if (right->type == EXPR_CALL && sym_name_is("strlen", right->fn)) {
 257                 str = get_argument_from_call_expr(right->args, 0);
 258                 strlen_right = 1;
 259         }
 260
 261         if (!strlen_left && !strlen_right)
 262                 return;
 263         if (strlen_left && strlen_right)
 264                 return;
 265
 266         if (strlen_left) {
 267                 if (!get_value(right, &val))
 268                         return;
 269         }
 270         if (strlen_right) {
 271                 if (!get_value(left, &val))
 272                         return;
 273         }
 274
 275         if (expr->op == SPECIAL_EQUAL) {
 276                 set_true_false_states_expr(my_size_id, str, alloc_state_num(val + 1), NULL);
 277                 return;
 278         }
 279         if (expr->op == SPECIAL_NOTEQUAL) {
 280                 set_true_false_states_expr(my_size_id, str, NULL, alloc_state_num(val + 1));
 281                 return;
 282         }
 283
 284         switch (expr->op) {
 285         case '<':
 286         case SPECIAL_UNSIGNED_LT:
 287                 if (strlen_left)
 288                         true_state = alloc_state_num(val);
 289                 else
 290                         false_state = alloc_state_num(val + 1);
 291                 break;
 292         case SPECIAL_LTE:
 293         case SPECIAL_UNSIGNED_LTE:
 294                 if (strlen_left)
 295                         true_state = alloc_state_num(val + 1);
 296                 else
 297                         false_state = alloc_state_num(val);
 298                 break;
 299         case SPECIAL_GTE:
 300         case SPECIAL_UNSIGNED_GTE:
 301                 if (strlen_left)
 302                         false_state = alloc_state_num(val);
 303                 else
 304                         true_state = alloc_state_num(val + 1);
 305                 break;
 306         case '>':
 307         case SPECIAL_UNSIGNED_GT:
 308                 if (strlen_left)
 309                         false_state = alloc_state_num(val + 1);
 310                 else
 311                         true_state = alloc_state_num(val);
 312                 break;
 313         }
 314         set_true_false_states_expr(my_size_id, str, true_state, false_state);
 315 }
 316
 317 static struct expression *strip_ampersands(struct expression *expr)
 318 {
 319         struct symbol *type;
 320
 321         if (expr->type != EXPR_PREOP)
 322                 return expr;
 323         if (expr->op != '&')
 324                 return expr;
 325         type = get_type(expr->unop);
 326         if (!type || type->type != SYM_ARRAY)
 327                 return expr;
 328         return expr->unop;
 329 }
 330
 331 static void match_array_assignment(struct expression *expr)
 332 {
 333         struct expression *left;
 334         struct expression *right;
 335         int array_size;
 336
 337         if (expr->op != '=')
 338                 return;
 339         left = strip_expr(expr->left);
 340         right = strip_expr(expr->right);
 341         right = strip_ampersands(right);
 342         array_size = get_array_size_bytes(right);
 343         if (array_size)
 344                 set_state_expr(my_size_id, left, alloc_state_num(array_size));
 345 }
 346
 347 static void match_alloc(const char *fn, struct expression *expr, void *_size_arg)
 348 {
 349         int size_arg = PTR_INT(_size_arg);
 350         struct expression *right;
 351         struct expression *arg;
 352         long long bytes;
 353
 354         right = strip_expr(expr->right);
 355         arg = get_argument_from_call_expr(right->args, size_arg);
 356         if (!get_implied_value(arg, &bytes))
 357                 return;
 358
 359         set_state_expr(my_size_id, expr->left, alloc_state_num(bytes));
 360
 361         if (option_info) {
 362                 char *member = get_member_name(expr->left);
 363
 364                 if (member)
 365                         sm_msg("info: '%s' allocated_buf_size %lld",
 366                                         member, bytes);
 367                 free_string(member);
 368         }
 369 }
 370
 371 static void match_calloc(const char *fn, struct expression *expr, void *unused)
 372 {
 373         struct expression *right;
 374         struct expression *arg;
 375         long long elements;
 376         long long size;
 377
 378         right = strip_expr(expr->right);
 379         arg = get_argument_from_call_expr(right->args, 0);
 380         if (!get_implied_value(arg, &elements))
 381                 return;
 382         arg = get_argument_from_call_expr(right->args, 1);
 383         if (!get_implied_value(arg, &size))
 384                 return;
 385         set_state_expr(my_size_id, expr->left, alloc_state_num(elements * size));
 386 }
 387
 388 static void match_strlen(const char *fn, struct expression *expr, void *unused)
 389 {
 390         struct expression *right;
 391         struct expression *str;
 392         struct expression *len_expr;
 393         char *len_name;
 394         struct smatch_state *state;
 395
 396         right = strip_expr(expr->right);
 397         str = get_argument_from_call_expr(right->args, 0);
 398         len_expr = strip_expr(expr->left);
 399
 400         len_name = get_variable_from_expr(len_expr, NULL);
 401         if (!len_name)
 402                 return;
 403
 404         state = __alloc_smatch_state(0);
 405         state->name = len_name;
 406         state->data = len_expr;
 407         set_state_expr(my_strlen_id, str, state);
 408 }
 409
 410 static void match_limited(const char *fn, struct expression *expr, void *_limiter)
 411 {
 412         struct limiter *limiter = (struct limiter *)_limiter;
 413         struct expression *dest;
 414         struct expression *size_expr;
 415         long long size;
 416
 417         dest = get_argument_from_call_expr(expr->args, limiter->buf_arg);
 418         size_expr = get_argument_from_call_expr(expr->args, limiter->limit_arg);
 419         if (!get_implied_max(size_expr, &size))
 420                 return;
 421         set_state_expr(my_size_id, dest, alloc_state_num(size));
 422 }
 423
 424 static void match_strcpy(const char *fn, struct expression *expr, void *unused)
 425 {
 426         struct expression fake_assign;
 427
 428         fake_assign.op = '=';
 429         fake_assign.left = get_argument_from_call_expr(expr->args, 0);
 430         fake_assign.right = get_argument_from_call_expr(expr->args, 1);
 431         match_array_assignment(&fake_assign);
 432 }
 433
 434 static void match_strndup(const char *fn, struct expression *expr, void *unused)
 435 {
 436         struct expression *fn_expr;
 437         struct expression *size_expr;
 438         long long size;
 439
 440         fn_expr = strip_expr(expr->right);
 441         size_expr = get_argument_from_call_expr(fn_expr->args, 1);
 442         if (!get_implied_max(size_expr, &size))
 443                 return;
 444
 445         /* It's easy to forget space for the NUL char */
 446         size++;
 447         set_state_expr(my_size_id, expr->left, alloc_state_num(size));
 448 }
 449
 450 static void match_call(struct expression *expr)
 451 {
 452         char *name;
 453         struct expression *arg;
 454         int bytes;
 455         int i;
 456
 457         name = get_fnptr_name(expr->fn);
 458         if (!name)
 459                 return;
 460
 461         i = 0;
 462         FOR_EACH_PTR(expr->args, arg) {
 463                 bytes = get_array_size_bytes(arg);
 464                 if (bytes > 1)
 465                         sm_msg("info: passes_buffer '%s' %d '$$' %d %s",
 466                                 name, i, bytes,
 467                                 is_static(expr->fn) ? "static" : "global");
 468                 i++;
 469         } END_FOR_EACH_PTR(arg);
 470
 471         free_string(name);
 472 }
 473
 474 static void struct_member_callback(char *fn, char *global_static, int param, char *printed_name, struct smatch_state *state)
 475 {
 476         if (state == &merged)
 477                 return;
 478         sm_msg("info: passes_buffer '%s' %d '%s' %s %s", fn, param, printed_name, state->name, global_static);
 479 }
 480
 481 static void match_func_end(struct symbol *sym)
 482 {
 483         memset(params_set, 0, sizeof(params_set));
 484 }
 485
 486 void register_buf_size(int id)
 487 {
 488         my_size_id = id;
 489
 490         add_definition_db_callback(set_param_buf_size, BUF_SIZE);
 491
 492         add_function_assign_hook("malloc", &match_alloc, INT_PTR(0));
 493         add_function_assign_hook("calloc", &match_calloc, NULL);
 494         add_function_assign_hook("memdup", &match_alloc, INT_PTR(1));
 495         if (option_project == PROJ_KERNEL) {
 496                 add_function_assign_hook("kmalloc", &match_alloc, INT_PTR(0));
 497                 add_function_assign_hook("kzalloc", &match_alloc, INT_PTR(0));
 498                 add_function_assign_hook("vmalloc", &match_alloc, INT_PTR(0));
 499                 add_function_assign_hook("__vmalloc", &match_alloc, INT_PTR(0));
 500                 add_function_assign_hook("kcalloc", &match_calloc, NULL);
 501                 add_function_assign_hook("drm_malloc_ab", &match_calloc, NULL);
 502                 add_function_assign_hook("drm_calloc_large", &match_calloc, NULL);
 503                 add_function_assign_hook("kmemdup", &match_alloc, INT_PTR(1));
 504                 add_function_assign_hook("kmemdup_user", &match_alloc, INT_PTR(1));
 505         }
 506         add_hook(&match_array_assignment, ASSIGNMENT_HOOK);
 507         add_hook(&match_strlen_condition, CONDITION_HOOK);
 508         add_function_assign_hook("strlen", &match_strlen, NULL);
 509
 510         add_function_hook("strlcpy", &match_limited, &b0_l2);
 511         add_function_hook("strlcat", &match_limited, &b0_l2);
 512         add_function_hook("memscan", &match_limited, &b0_l2);
 513
 514         add_function_hook("strcpy", &match_strcpy, NULL);
 515
 516         add_function_assign_hook("strndup", match_strndup, NULL);
 517         if (option_project == PROJ_KERNEL)
 518                 add_function_assign_hook("kstrndup", match_strndup, NULL);
 519
 520         if (option_info) {
 521                 add_hook(&match_call, FUNCTION_CALL_HOOK);
 522                 add_member_info_callback(my_size_id, struct_member_callback);
 523         }
 524
 525         add_hook(&match_func_end, END_FUNC_HOOK);
 526         add_modification_hook(my_size_id, &set_undefined);
 527 }
 528
 529 void register_strlen(int id)
 530 {
 531         my_strlen_id = id;
 532         add_modification_hook(my_strlen_id, &set_undefined);
 533 }