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 static bool binop_capped(struct expression *expr)
  70 {
  71         struct range_list *left_rl, *right_rl;
  72         sval_t sval;
  73
  74         if (expr->op == '&' && !get_value(expr->right, &sval))
  75                 return true;
  76         if (expr->op == SPECIAL_RIGHTSHIFT)
  77                 return false;
  78         if (expr->op == '%' &&
  79             !get_value(expr->right, &sval) && is_capped(expr->right))
  80                 return true;
  81         if (!is_capped(expr->left))
  82                 return false;
  83         if (expr->op == '/')
  84                 return true;
  85         if (!is_capped(expr->right))
  86                 return false;
  87         if (expr->op == '*') {
  88                 get_absolute_rl(expr->left, &left_rl);
  89                 get_absolute_rl(expr->right, &right_rl);
  90                 if (sval_is_negative(rl_min(left_rl)) ||
  91                     sval_is_negative(rl_min(right_rl)))
  92                         return false;
  93         }
  94         return true;
  95 }
  96
  97 int is_capped(struct expression *expr)
  98 {
  99         struct symbol *type;
 100
 101         expr = strip_expr(expr);
 102         while (expr && expr->type == EXPR_POSTOP) {
 103                 expr = strip_expr(expr->unop);
 104         }
 105         if (!expr)
 106                 return 0;
 107
 108         type = get_type(expr);
 109         if (is_ptr_type(type))
 110                 return 0;
 111         if (type == &bool_ctype)
 112                 return 0;
 113         if (type_bits(type) >= 0 && type_bits(type) <= 2)
 114                 return 0;
 115
 116         if (is_capped_macro(expr))
 117                 return 1;
 118
 119         if (expr->type == EXPR_BINOP)
 120                 return binop_capped(expr);
 121
 122         if (get_state_expr(my_id, expr) == &capped)
 123                 return 1;
 124         return 0;
 125 }
 126
 127 int is_capped_var_sym(const char *name, struct symbol *sym)
 128 {
 129         if (get_state(my_id, name, sym) == &capped)
 130                 return 1;
 131         return 0;
 132 }
 133
 134 void set_param_capped_data(const char *name, struct symbol *sym, char *key, char *value)
 135 {
 136         char fullname[256];
 137
 138         if (strncmp(key, "$", 1))
 139                 return;
 140         snprintf(fullname, 256, "%s%s", name, key + 1);
 141         set_state(my_id, fullname, sym, &capped);
 142 }
 143
 144 static void match_condition(struct expression *expr)
 145 {
 146         struct expression *left, *right;
 147         struct smatch_state *left_true = NULL;
 148         struct smatch_state *left_false = NULL;
 149         struct smatch_state *right_true = NULL;
 150         struct smatch_state *right_false = NULL;
 151         sval_t sval;
 152
 153
 154         if (expr->type != EXPR_COMPARE)
 155                 return;
 156
 157         left = strip_expr(expr->left);
 158         right = strip_expr(expr->right);
 159
 160         while (left->type == EXPR_ASSIGNMENT)
 161                 left = strip_expr(left->left);
 162
 163         /* If we're dealing with known expressions, that's for smatch_extra.c */
 164         if (get_implied_value(left, &sval) ||
 165             get_implied_value(right, &sval))
 166                 return;
 167
 168         switch (expr->op) {
 169         case '<':
 170         case SPECIAL_LTE:
 171         case SPECIAL_UNSIGNED_LT:
 172         case SPECIAL_UNSIGNED_LTE:
 173                 left_true = &capped;
 174                 right_false = &capped;
 175                 break;
 176         case '>':
 177         case SPECIAL_GTE:
 178         case SPECIAL_UNSIGNED_GT:
 179         case SPECIAL_UNSIGNED_GTE:
 180                 left_false = &capped;
 181                 right_true = &capped;
 182                 break;
 183         case SPECIAL_EQUAL:
 184                 left_true = &capped;
 185                 right_true = &capped;
 186                 break;
 187         case SPECIAL_NOTEQUAL:
 188                 left_false = &capped;
 189                 right_false = &capped;
 190                 break;
 191
 192         default:
 193                 return;
 194         }
 195
 196         set_true_false_states_expr(my_id, left, left_true, left_false);
 197         set_true_false_states_expr(my_id, right, right_true, right_false);
 198 }
 199
 200 static void match_assign(struct expression *expr)
 201 {
 202         struct symbol *type;
 203
 204         type = get_type(expr);
 205         if (is_ptr_type(type))
 206                 return;
 207         if (type == &bool_ctype)
 208                 return;
 209         if (type_bits(type) >= 0 && type_bits(type) <= 2)
 210                 return;
 211
 212         if (is_capped(expr->right)) {
 213                 set_state_expr(my_id, expr->left, &capped);
 214         } else {
 215                 if (get_state_expr(my_id, expr->left))
 216                         set_state_expr(my_id, expr->left, &uncapped);
 217         }
 218 }
 219
 220 static void match_caller_info(struct expression *expr)
 221 {
 222         struct expression *tmp;
 223         sval_t sval;
 224         int i;
 225
 226         i = -1;
 227         FOR_EACH_PTR(expr->args, tmp) {
 228                 i++;
 229                 if (get_implied_value(tmp, &sval))
 230                         continue;
 231                 if (!is_capped(tmp))
 232                         continue;
 233                 sql_insert_caller_info(expr, CAPPED_DATA, i, "$", "1");
 234         } END_FOR_EACH_PTR(tmp);
 235 }
 236
 237 static void struct_member_callback(struct expression *call, int param, char *printed_name, struct sm_state *sm)
 238 {
 239         struct smatch_state *estate;
 240         sval_t sval;
 241
 242         if (sm->state != &capped)
 243                 return;
 244         estate = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
 245         if (estate_get_single_value(estate, &sval))
 246                 return;
 247         sql_insert_caller_info(call, CAPPED_DATA, param, printed_name, "1");
 248 }
 249
 250 static void print_return_implies_capped(int return_id, char *return_ranges, struct expression *expr)
 251 {
 252         struct smatch_state *orig, *estate;
 253         struct sm_state *sm;
 254         struct symbol *ret_sym;
 255         const char *param_name;
 256         char *return_str;
 257         int param;
 258         sval_t sval;
 259         bool return_found = false;
 260
 261         expr = strip_expr(expr);
 262         return_str = expr_to_str(expr);
 263         ret_sym = expr_to_sym(expr);
 264
 265         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 266                 if (sm->state != &capped)
 267                         continue;
 268
 269                 param = get_param_num_from_sym(sm->sym);
 270                 if (param < 0)
 271                         continue;
 272
 273                 estate = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
 274                 if (estate_get_single_value(estate, &sval))
 275                         continue;
 276
 277                 orig = get_state_stree(get_start_states(), my_id, sm->name, sm->sym);
 278                 if (orig == &capped && !param_was_set_var_sym(sm->name, sm->sym))
 279                         continue;
 280
 281                 param_name = get_param_name(sm);
 282                 if (!param_name)
 283                         continue;
 284
 285                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 286                                          param, param_name, "1");
 287         } END_FOR_EACH_SM(sm);
 288
 289         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 290                 if (!ret_sym)
 291                         break;
 292                 if (sm->state != &capped)
 293                         continue;
 294                 if (ret_sym != sm->sym)
 295                         continue;
 296
 297                 estate = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
 298                 if (estate_get_single_value(estate, &sval))
 299                         continue;
 300
 301                 param_name = state_name_to_param_name(sm->name, return_str);
 302                 if (!param_name)
 303                         continue;
 304                 if (strcmp(param_name, "$") == 0)
 305                         return_found = true;
 306                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 307                                          -1, param_name, "1");
 308         } END_FOR_EACH_SM(sm);
 309
 310         if (return_found)
 311                 goto free_string;
 312
 313         if (option_project == PROJ_KERNEL && get_function() &&
 314             strstr(get_function(), "nla_get_"))
 315                 sql_insert_return_states(return_id, return_ranges, CAPPED_DATA,
 316                                          -1, "$", "1");
 317
 318 free_string:
 319         free_string(return_str);
 320 }
 321
 322 static void db_return_states_capped(struct expression *expr, int param, char *key, char *value)
 323 {
 324         char *name;
 325         struct symbol *sym;
 326
 327         name = return_state_to_var_sym(expr, param, key, &sym);
 328         if (!name || !sym)
 329                 goto free;
 330
 331         set_state(my_id, name, sym, &capped);
 332 free:
 333         free_string(name);
 334 }
 335
 336 void register_capped(int id)
 337 {
 338         my_id = id;
 339
 340         add_unmatched_state_hook(my_id, &unmatched_state);
 341         select_caller_info_hook(set_param_capped_data, CAPPED_DATA);
 342         add_hook(&match_condition, CONDITION_HOOK);
 343         add_hook(&match_assign, ASSIGNMENT_HOOK);
 344         add_modification_hook(my_id, &set_uncapped);
 345
 346         add_hook(&match_caller_info, FUNCTION_CALL_HOOK);
 347         add_member_info_callback(my_id, struct_member_callback);
 348
 349         add_split_return_callback(print_return_implies_capped);
 350         select_return_states_hook(CAPPED_DATA, &db_return_states_capped);
 351 }