smatch_capped.c

   1 /*
   2  * Copyright (C) 2011 Oracle.  All rights reserved.
   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  * This is trying to make a list of the variables which
  20  * have capped values.  Sometimes we don't know what the
  21  * cap is, for example if we are comparing variables but
  22  * we don't know the values of the variables.  In that
  23  * case we only know that our variable is capped and we
  24  * sort that information here.
  25  */
  26
  27 #include "smatch.h"
  28 #include "smatch_slist.h"
  29 #include "smatch_extra.h"
  30
  31 static int my_id;
  32
  33 STATE(capped);
  34 STATE(uncapped);
  35
  36 static void set_uncapped(struct sm_state *sm, struct expression *mod_expr)
  37 {
  38         set_state(my_id, sm->name, sm->sym, &uncapped);
  39 }
  40
  41 static struct smatch_state *unmatched_state(struct sm_state *sm)
  42 {
  43         struct smatch_state *state;
  44
  45         state = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
  46         if (state && !estate_is_whole(state))
  47                 return &capped;
  48         return &uncapped;
  49 }
  50
  51 static int is_capped_macro(struct expression *expr)
  52 {
  53         char *name;
  54
  55         name = get_macro_name(expr->pos);
  56         if (!name)
  57                 return 0;
  58
  59         if (strcmp(name, "min") == 0)
  60                 return 1;
  61         if (strcmp(name, "MIN") == 0)
  62                 return 1;
  63         if (strcmp(name, "min_t") == 0)
  64                 return 1;
  65
  66         return 0;
  67 }
  68
  69 int is_capped(struct expression *expr)
  70 {
  71         struct symbol *type;
  72         sval_t dummy;
  73
  74         expr = strip_expr(expr);
  75         while (expr && expr->type == EXPR_POSTOP) {
  76                 expr = strip_expr(expr->unop);
  77         }
  78         if (!expr)
  79                 return 0;
  80
  81         type = get_type(expr);
  82         if (is_ptr_type(type))
  83                 return 0;
  84         if (type == &bool_ctype)
  85                 return 0;
  86         if (type_bits(type) >= 0 && type_bits(type) <= 2)
  87                 return 0;
  88
  89         if (get_hard_max(expr, &dummy))
  90                 return 1;
  91
  92         if (is_capped_macro(expr))
  93                 return 1;
  94
  95         if (expr->type == EXPR_BINOP) {
  96                 struct range_list *left_rl, *right_rl;
  97                 sval_t sval;
  98
  99                 if (expr->op == '&' && !get_value(expr->right, &sval))
 100                         return 1;
 101                 if (expr->op == SPECIAL_RIGHTSHIFT)
 102                         return 0;
 103                 if (expr->op == '%' &&
 104                     !get_value(expr->right, &sval) && is_capped(expr->right))
 105                         return 1;
 106                 if (!is_capped(expr->left))
 107                         return 0;
 108                 if (expr->op == '/')
 109                         return 1;
 110                 if (!is_capped(expr->right))
 111                         return 0;
 112                 if (expr->op == '*') {
 113                         get_absolute_rl(expr->left, &left_rl);
 114                         get_absolute_rl(expr->right, &right_rl);
 115                         if (sval_is_negative(rl_min(left_rl)) ||
 116                             sval_is_negative(rl_min(right_rl)))
 117                                 return 0;
 118                 }
 119                 return 1;
 120         }
 121         if (get_state_expr(my_id, expr) == &capped)
 122                 return 1;
 123         return 0;
 124 }
 125
 126 int is_capped_var_sym(const char *name, struct symbol *sym)
 127 {
 128         if (get_state(my_id, name, sym) == &capped)
 129                 return 1;
 130         return 0;
 131 }
 132
 133 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
 134 {
 135         char fullname[256];
 136
 137         if (strncmp(key, "$", 1))
 138                 return;
 139         snprintf(fullname, 256, "%s%s", name, key + 1);
 140         set_state(my_id, fullname, sym, &capped);
 141 }
 142
 143 static void match_condition(struct expression *expr)
 144 {
 145         struct expression *left, *right;
 146         struct smatch_state *left_true = NULL;
 147         struct smatch_state *left_false = NULL;
 148         struct smatch_state *right_true = NULL;
 149         struct smatch_state *right_false = NULL;
 150         sval_t sval;
 151
 152
 153         if (expr->type != EXPR_COMPARE)
 154                 return;
 155
 156         left = strip_expr(expr->left);
 157         right = strip_expr(expr->right);
 158
 159         while (left->type == EXPR_ASSIGNMENT)
 160                 left = strip_expr(left->left);
 161
 162         /* If we're dealing with known expressions, that's for smatch_extra.c */
 163         if (get_implied_value(left, &sval) ||
 164             get_implied_value(right, &sval))
 165                 return;
 166
 167         switch (expr->op) {
 168         case '<':
 169         case SPECIAL_LTE:
 170         case SPECIAL_UNSIGNED_LT:
 171         case SPECIAL_UNSIGNED_LTE:
 172                 left_true = &capped;
 173                 right_false = &capped;
 174                 break;
 175         case '>':
 176         case SPECIAL_GTE:
 177         case SPECIAL_UNSIGNED_GT:
 178         case SPECIAL_UNSIGNED_GTE:
 179                 left_false = &capped;
 180                 right_true = &capped;
 181                 break;
 182         case SPECIAL_EQUAL:
 183                 left_true = &capped;
 184                 right_true = &capped;
 185                 break;
 186         case SPECIAL_NOTEQUAL:
 187                 left_false = &capped;
 188                 right_false = &capped;
 189                 break;
 190
 191         default:
 192                 return;
 193         }
 194
 195         set_true_false_states_expr(my_id, left, left_true, left_false);
 196         set_true_false_states_expr(my_id, right, right_true, right_false);
 197 }
 198
 199 static void match_assign(struct expression *expr)
 200 {
 201         struct symbol *type;
 202
 203         type = get_type(expr);
 204         if (is_ptr_type(type))
 205                 return;
 206         if (type == &bool_ctype)
 207                 return;
 208         if (type_bits(type) >= 0 && type_bits(type) <= 2)
 209                 return;
 210
 211         if (is_capped(expr->right)) {
 212                 set_state_expr(my_id, expr->left, &capped);
 213         } else {
 214                 if (get_state_expr(my_id, expr->left))
 215                         set_state_expr(my_id, expr->left, &uncapped);
 216         }
 217 }
 218
 219 static void match_caller_info(struct expression *expr)
 220 {
 221         struct expression *tmp;
 222         sval_t sval;
 223         int i;
 224
 225         i = -1;
 226         FOR_EACH_PTR(expr->args, tmp) {
 227                 i++;
 228                 if (get_implied_value(tmp, &sval))
 229                         continue;
 230                 if (!is_capped(tmp))
 231                         continue;
 232                 sql_insert_caller_info(expr, CAPPED_DATA, i, "$", "1");
 233         } END_FOR_EACH_PTR(tmp);
 234 }
 235
 236 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
 237 {
 238         struct smatch_state *estate;
 239         sval_t sval;
 240
 241         if (sm->state != &capped)
 242                 return;
 243         estate = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
 244         if (estate_get_single_value(estate, &sval))
 245                 return;
 246         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 247 }
 248
 249 static void print_return_implies_capped(int return_id, char *return_ranges, struct expression *expr)
 250 {
 251         struct smatch_state *orig, *estate;
 252         struct sm_state *sm;
 253         struct symbol *ret_sym;
 254         const char *param_name;
 255         char *return_str;
 256         int param;
 257         sval_t sval;
 258         bool return_found = false;
 259
 260         expr = strip_expr(expr);
 261         return_str = expr_to_str(expr);
 262         ret_sym = expr_to_sym(expr);
 263
 264         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 265                 if (sm->state != &capped)
 266                         continue;
 267
 268                 param = get_param_num_from_sym(sm->sym);
 269                 if (param < 0)
 270                         continue;
 271
 272                 estate = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
 273                 if (estate_get_single_value(estate, &sval))
 274                         continue;
 275
 276                 orig = get_state_stree(get_start_states(), my_id, sm->name, sm->sym);
 277                 if (orig == &capped && !param_was_set_var_sym(sm->name, sm->sym))
 278                         continue;
 279
 280                 param_name = get_param_name(sm);
 281                 if (!param_name)
 282                         continue;
 283
 284                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 285                                          param, param_name, "1");
 286         } END_FOR_EACH_SM(sm);
 287
 288         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 289                 if (!ret_sym)
 290                         break;
 291                 if (sm->state != &capped)
 292                         continue;
 293                 if (ret_sym != sm->sym)
 294                         continue;
 295
 296                 estate = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
 297                 if (estate_get_single_value(estate, &sval))
 298                         continue;
 299
 300                 param_name = state_name_to_param_name(sm->name, return_str);
 301                 if (!param_name)
 302                         continue;
 303                 if (strcmp(param_name, "$") == 0)
 304                         return_found = true;
 305                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 306                                          -1, param_name, "1");
 307         } END_FOR_EACH_SM(sm);
 308
 309         if (return_found)
 310                 goto free_string;
 311
 312         if (option_project == PROJ_KERNEL && get_function() &&
 313             strstr(get_function(), "nla_get_"))
 314                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 315                                          -1, "$", "1");
 316
 317 free_string:
 318         free_string(return_str);
 319 }
 320
 321 static void db_return_states_capped(struct expression *expr, int param, char *key, char *value)
 322 {
 323         char *name;
 324         struct symbol *sym;
 325
 326         name = return_state_to_var_sym(expr, param, key, &sym);
 327         if (!name || !sym)
 328                 goto free;
 329
 330         set_state(my_id, name, sym, &capped);
 331 free:
 332         free_string(name);
 333 }
 334
 335 void register_capped(int id)
 336 {
 337         my_id = id;
 338
 339         add_unmatched_state_hook(my_id, &unmatched_state);
 340         select_caller_info_hook(set_param_capped_data, CAPPED_DATA);
 341         add_hook(&match_condition, CONDITION_HOOK);
 342         add_hook(&match_assign, ASSIGNMENT_HOOK);
 343         add_modification_hook(my_id, &set_uncapped);
 344
 345         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 346         add_member_info_callback(my_id, struct_member_callback);
 347
 348         add_split_return_callback(print_return_implies_capped);
 349         select_return_states_hook(CAPPED_DATA, &db_return_states_capped);
 350 }