check_uninitialized.c

   1 /*
   2  * Copyright (C) 2014 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 #include "smatch.h"
  19 #include "smatch_slist.h"
  20 #include "smatch_extra.h"
  21
  22 static int my_id;
  23
  24 STATE(uninitialized);
  25 STATE(initialized);
  26
  27 static void pre_merge_hook(struct sm_state *cur, struct sm_state *other)
  28 {
  29         if (is_impossible_path())
  30                 set_state(my_id, cur->name, cur->sym, &initialized);
  31 }
  32
  33 static void mark_members_uninitialized(struct symbol *sym)
  34 {
  35         struct symbol *struct_type, *tmp, *base_type;
  36         char buf[256];
  37
  38         struct_type = get_real_base_type(sym);
  39         FOR_EACH_PTR(struct_type->symbol_list, tmp) {
  40                 if (!tmp->ident)
  41                         continue;
  42                 base_type = get_real_base_type(tmp);
  43                 if (!base_type ||
  44                     base_type->type == SYM_STRUCT ||
  45                     base_type->type == SYM_ARRAY ||
  46                     base_type->type == SYM_UNION)
  47                         continue;
  48                 snprintf(buf, sizeof(buf), "%s.%s", sym->ident->name, tmp->ident->name);
  49                 set_state(my_id, buf, sym, &uninitialized);
  50         } END_FOR_EACH_PTR(tmp);
  51 }
  52
  53 static void match_declarations(struct symbol *sym)
  54 {
  55         struct symbol *type;
  56
  57         if (sym->initializer)
  58                 return;
  59
  60         type = get_real_base_type(sym);
  61         /* Smatch is crap at tracking arrays */
  62         if (type->type == SYM_ARRAY)
  63                 return;
  64         if (type->type == SYM_UNION)
  65                 return;
  66         if (sym->ctype.modifiers & MOD_STATIC)
  67                 return;
  68
  69         if (!sym->ident)
  70                 return;
  71
  72         if (type->type == SYM_STRUCT) {
  73                 mark_members_uninitialized(sym);
  74                 return;
  75         }
  76
  77         set_state(my_id, sym->ident->name, sym, &uninitialized);
  78 }
  79
  80 static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
  81 {
  82         if (__in_fake_struct_assign)
  83                 return;
  84         if (expr && expr->smatch_flags & Fake)
  85                 return;
  86         if (!sym || !sym->ident)
  87                 return;
  88         if (strcmp(name, sym->ident->name) != 0)
  89                 return;
  90         set_state(my_id, name, sym, &initialized);
  91 }
  92
  93 static void match_assign(struct expression *expr)
  94 {
  95         struct expression *right;
  96
  97         right = strip_expr(expr->right);
  98         if (right->type == EXPR_PREOP && right->op == '&')
  99                 set_state_expr(my_id, right->unop, &initialized);
 100 }
 101
 102 static void match_negative_comparison(struct expression *expr)
 103 {
 104         struct expression *success;
 105         struct sm_state *sm;
 106         sval_t max;
 107
 108         /*
 109          * In the kernel, people don't use "if (ret) {" and "if (ret < 0) {"
 110          * consistently.  Ideally Smatch would know the return but often it
 111          * doesn't.
 112          *
 113          */
 114
 115         if (option_project != PROJ_KERNEL)
 116                 return;
 117
 118         if (expr->type != EXPR_COMPARE || expr->op != '<')
 119                 return;
 120         if (!expr_is_zero(expr->right))
 121                 return;
 122         if (get_implied_max(expr->left, &max) && max.value == 0)
 123                 return;
 124
 125         success = compare_expression(expr->left, SPECIAL_EQUAL, expr->right);
 126         if (!assume(success))
 127                 return;
 128
 129         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 130                 if (sm->state == &initialized)
 131                         set_true_false_states(my_id, sm->name, sm->sym, NULL, &initialized);
 132         } END_FOR_EACH_SM(sm);
 133
 134         end_assume();
 135 }
 136
 137 static int is_initialized(struct expression *expr)
 138 {
 139         struct sm_state *sm;
 140
 141         expr = strip_expr(expr);
 142         if (expr->type != EXPR_SYMBOL)
 143                 return 1;
 144         sm = get_sm_state_expr(my_id, expr);
 145         if (!sm)
 146                 return 1;
 147         if (!slist_has_state(sm->possible, &uninitialized))
 148                 return 1;
 149         return 0;
 150 }
 151
 152 static void match_dereferences(struct expression *expr)
 153 {
 154         char *name;
 155
 156         if (implications_off || parse_error)
 157                 return;
 158
 159         if (expr->type != EXPR_PREOP)
 160                 return;
 161         if (is_impossible_path())
 162                 return;
 163         if (is_initialized(expr->unop))
 164                 return;
 165
 166         name = expr_to_str(expr->unop);
 167         sm_error("potentially dereferencing uninitialized '%s'.", name);
 168         free_string(name);
 169
 170         set_state_expr(my_id, expr->unop, &initialized);
 171 }
 172
 173 static void match_condition(struct expression *expr)
 174 {
 175         char *name;
 176
 177         if (implications_off || parse_error)
 178                 return;
 179
 180         if (is_impossible_path())
 181                 return;
 182
 183         if (is_initialized(expr))
 184                 return;
 185
 186         name = expr_to_str(expr);
 187         sm_error("potentially using uninitialized '%s'.", name);
 188         free_string(name);
 189
 190         set_state_expr(my_id, expr, &initialized);
 191 }
 192
 193 static void match_call(struct expression *expr)
 194 {
 195         struct expression *arg;
 196         char *name;
 197
 198         if (parse_error)
 199                 return;
 200
 201         if (is_impossible_path())
 202                 return;
 203
 204         FOR_EACH_PTR(expr->args, arg) {
 205                 if (is_initialized(arg))
 206                         continue;
 207
 208                 name = expr_to_str(arg);
 209                 sm_warning("passing uninitialized '%s'", name);
 210                 free_string(name);
 211
 212                 set_state_expr(my_id, arg, &initialized);
 213         } END_FOR_EACH_PTR(arg);
 214 }
 215
 216 static int param_used_callback(void *found, int argc, char **argv, char **azColName)
 217 {
 218         *(int *)found = 1;
 219         return 0;
 220 }
 221
 222 static int member_is_used(struct expression *call, int param, char *printed_name)
 223 {
 224         int found;
 225
 226         /* for function pointers assume everything is used */
 227         if (call->fn->type != EXPR_SYMBOL)
 228                 return 0;
 229
 230         found = 0;
 231         run_sql(&param_used_callback, &found,
 232                 "select * from return_implies where %s and type = %d and parameter = %d and key = '%s';",
 233                 get_static_filter(call->fn->symbol), PARAM_USED, param, printed_name);
 234         return found;
 235 }
 236
 237 static void match_call_struct_members(struct expression *expr)
 238 {
 239         struct symbol *type, *sym;
 240         struct expression *arg;
 241         struct sm_state *sm;
 242         char *arg_name;
 243         char buf[256];
 244         int param;
 245
 246         return;
 247
 248         if (parse_error)
 249                 return;
 250
 251         param = -1;
 252         FOR_EACH_PTR(expr->args, arg) {
 253                 param++;
 254                 if (arg->type != EXPR_PREOP || arg->op != '&')
 255                         continue;
 256                 type = get_type(arg->unop);
 257                 if (!type || type->type != SYM_STRUCT)
 258                         continue;
 259                 arg_name = expr_to_var_sym(arg->unop, &sym);
 260                 if (!arg_name || !sym)
 261                         goto free;
 262                 FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 263                         if (sm->sym != sym)
 264                                 continue;
 265                         if (!slist_has_state(sm->possible, &uninitialized))
 266                                 continue;
 267                         snprintf(buf, sizeof(buf), "$->%s", sm->name + strlen(arg_name) + 1);
 268                         if (!member_is_used(expr, param, buf))
 269                                 goto free;
 270                         sm_warning("struct member %s is uninitialized", sm->name);
 271                 } END_FOR_EACH_SM(sm);
 272
 273 free:
 274                 free_string(arg_name);
 275         } END_FOR_EACH_PTR(arg);
 276 }
 277
 278 static int is_being_modified(struct expression *expr)
 279 {
 280         struct expression *parent;
 281         struct statement *stmt;
 282
 283         parent = expr_get_parent_expr(expr);
 284         if (!parent)
 285                 return 0;
 286         while (parent->type == EXPR_PREOP && parent->op == '(') {
 287                 parent = expr_get_parent_expr(parent);
 288                 if (!parent)
 289                         return 0;
 290         }
 291         if (parent->type == EXPR_PREOP && parent->op == '&')
 292                 return 1;
 293         if (parent->type == EXPR_ASSIGNMENT && expr_equiv(parent->left, expr))
 294                 return 1;
 295
 296         stmt = last_ptr_list((struct ptr_list *)big_statement_stack);
 297         if (stmt && stmt->type == STMT_ASM)
 298                 return 1;
 299
 300         return 0;
 301 }
 302
 303 static bool is_just_silencing_used_variable(struct expression *expr)
 304 {
 305         struct symbol *type;
 306
 307         while ((expr = expr_get_parent_expr(expr))) {
 308                 if (expr->type == EXPR_PREOP && expr->op == '(')
 309                         continue;
 310                 if (expr->type == EXPR_CAST) {
 311                         type = expr->cast_type;
 312
 313                         if (!type)
 314                                 return false;
 315                         if (type->type == SYM_NODE)
 316                                 type = get_real_base_type(type);
 317                         if (type == &void_ctype)
 318                                 return true;
 319                 }
 320         }
 321
 322         return false;
 323 }
 324
 325 static void match_symbol(struct expression *expr)
 326 {
 327         char *name;
 328
 329         if (implications_off || parse_error)
 330                 return;
 331
 332         if (is_impossible_path())
 333                 return;
 334
 335         if (is_initialized(expr))
 336                 return;
 337
 338         if (is_being_modified(expr))
 339                 return;
 340
 341         if (is_just_silencing_used_variable(expr))
 342                 return;
 343
 344         name = expr_to_str(expr);
 345         sm_error("uninitialized symbol '%s'.", name);
 346         free_string(name);
 347
 348         set_state_expr(my_id, expr, &initialized);
 349 }
 350
 351 static void match_untracked(struct expression *call, int param)
 352 {
 353         struct expression *arg;
 354
 355         arg = get_argument_from_call_expr(call->args, param);
 356         arg = strip_expr(arg);
 357         if (!arg || arg->type != EXPR_PREOP || arg->op != '&')
 358                 return;
 359         arg = strip_expr(arg->unop);
 360         set_state_expr(my_id, arg, &initialized);
 361 }
 362
 363 static void match_ignore_param(const char *fn, struct expression *expr, void *_arg_nr)
 364 {
 365         int arg_nr = PTR_INT(_arg_nr);
 366         struct expression *arg;
 367
 368         arg = get_argument_from_call_expr(expr->args, arg_nr);
 369         arg = strip_expr(arg);
 370         if (!arg)
 371                 return;
 372         if (arg->type != EXPR_PREOP || arg->op != '&')
 373                 return;
 374         arg = strip_expr(arg->unop);
 375         set_state_expr(my_id, arg, &initialized);
 376 }
 377
 378 static void register_ignored_params_from_file(void)
 379 {
 380         char name[256];
 381         struct token *token;
 382         const char *func;
 383         char prev_func[256];
 384         int param;
 385
 386         memset(prev_func, 0, sizeof(prev_func));
 387         snprintf(name, 256, "%s.ignore_uninitialized_param", option_project_str);
 388         name[255] = '\0';
 389         token = get_tokens_file(name);
 390         if (!token)
 391                 return;
 392         if (token_type(token) != TOKEN_STREAMBEGIN)
 393                 return;
 394         token = token->next;
 395         while (token_type(token) != TOKEN_STREAMEND) {
 396                 if (token_type(token) != TOKEN_IDENT)
 397                         return;
 398                 func = show_ident(token->ident);
 399
 400                 token = token->next;
 401                 if (token_type(token) != TOKEN_NUMBER)
 402                         return;
 403                 param = atoi(token->number);
 404
 405                 add_function_hook(func, &match_ignore_param, INT_PTR(param));
 406
 407                 token = token->next;
 408         }
 409         clear_token_alloc();
 410 }
 411
 412 void check_uninitialized(int id)
 413 {
 414         my_id = id;
 415
 416         add_hook(&match_declarations, DECLARATION_HOOK);
 417         add_extra_mod_hook(&extra_mod_hook);
 418         add_hook(&match_assign, ASSIGNMENT_HOOK);
 419         add_hook(&match_negative_comparison, CONDITION_HOOK);
 420         add_untracked_param_hook(&match_untracked);
 421         add_pre_merge_hook(my_id, &pre_merge_hook);
 422
 423         add_hook(&match_dereferences, DEREF_HOOK);
 424         add_hook(&match_condition, CONDITION_HOOK);
 425         add_hook(&match_call, FUNCTION_CALL_HOOK);
 426         add_hook(&match_call_struct_members, FUNCTION_CALL_HOOK);
 427         add_hook(&match_symbol, SYM_HOOK);
 428
 429         register_ignored_params_from_file();
 430 }