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