check_unwind.c

   1 /*
   2  * Copyright (C) 2020 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 <ctype.h>
  19
  20 #include "smatch.h"
  21 #include "smatch_extra.h"
  22 #include "smatch_slist.h"
  23
  24 static int my_id;
  25
  26 STATE(alloc);
  27 STATE(release);
  28 STATE(param_released);
  29 STATE(ignore);
  30
  31 static unsigned long fn_has_alloc;
  32
  33 struct ref_func_info {
  34         const char *name;
  35         int type;
  36         int param;
  37         const char *key;
  38         const sval_t *implies_start, *implies_end;
  39         func_hook *call_back;
  40 };
  41
  42 static struct ref_func_info func_table[] = {
  43         { "clk_prepare_enable", ALLOC, 0, "$", &int_zero, &int_zero },
  44         { "clk_disable_unprepare", RELEASE, 0, "$" },
  45
  46         { "alloc_etherdev_mqs", ALLOC, -1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
  47         { "free_netdev", RELEASE, 0, "$" },
  48
  49         /*
  50          * FIXME: A common pattern in release functions like amd76xrom_cleanup()
  51          * is to do:
  52          *
  53          *      if (window->rsrc.parent)
  54          *              release_resource(&window->rsrc);
  55          *
  56          * Which is slightly tricky to know how to merge the states so let's
  57          * hold off checking request_resource() for now.
  58          *
  59          * { "request_resource", ALLOC,   1, "$", &int_zero, &int_zero },
  60          * { "release_resource", RELEASE, 0, "$" },
  61          *
  62          */
  63
  64         { "pci_request_regions", ALLOC,   0, "$", &int_zero, &int_zero },
  65         { "pci_release_regions", RELEASE, 0, "$" },
  66
  67         { "request_free_mem_region", ALLOC,   -1, "$->start", &valid_ptr_min_sval, &valid_ptr_max_sval },
  68         { "__request_region", ALLOC,   1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
  69         { "__release_region", RELEASE, 1, "$" },
  70
  71         { "ioremap", ALLOC,  -1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
  72         { "of_iomap", ALLOC,  -1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
  73         { "ioremap_encrypted", ALLOC,  -1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
  74         { "iounmap", RELEASE, 0, "$" },
  75
  76         { "request_threaded_irq", ALLOC,   0, "$", &int_zero, &int_zero },
  77         { "request_irq", ALLOC,   0, "$", &int_zero, &int_zero },
  78         { "free_irq",    RELEASE, 0, "$" },
  79         { "pci_request_irq", ALLOC,   1, "$", &int_zero, &int_zero },
  80         { "pci_free_irq",    RELEASE, 1, "$" },
  81
  82         { "register_netdev",   ALLOC,   0, "$", &int_zero, &int_zero },
  83         { "unregister_netdev", RELEASE, 0, "$" },
  84
  85         { "misc_register",   ALLOC,   0, "$", &int_zero, &int_zero },
  86         { "misc_deregister", RELEASE, 0, "$" },
  87
  88         { "ieee80211_alloc_hw", ALLOC,  -1, "$", &valid_ptr_min_sval, &valid_ptr_max_sval },
  89         { "ieee80211_free_hw",  RELEASE, 0, "$" },
  90 };
  91
  92 struct smatch_state *unmatched_state(struct sm_state *sm)
  93 {
  94         struct smatch_state *state;
  95
  96         if (sm->state != &param_released)
  97                 return &undefined;
  98
  99         if (is_impossible_path())
 100                 return &param_released;
 101
 102         state = get_state(SMATCH_EXTRA, sm->name, sm->sym);
 103         if (!state)
 104                 return &undefined;
 105         if (!estate_rl(state) || is_err_or_null(estate_rl(state)))
 106                 return &param_released;
 107         if (parent_is_err_or_null_var_sym(sm->name, sm->sym))
 108                 return &param_released;
 109
 110          return &undefined;
 111 }
 112
 113 static struct sm_state *get_start_sm(const char *name, struct symbol *sym)
 114 {
 115         struct sm_state *sm;
 116
 117         sm = get_sm_state(my_id, name, sym);
 118         if (sm)
 119                 return sm;
 120
 121         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 122                 if (get_comparison_strings(name, sm->name) == SPECIAL_EQUAL)
 123                         return sm;
 124         } END_FOR_EACH_SM(sm);
 125
 126         return NULL;
 127 }
 128
 129 static bool is_param_var_sym(const char *name, struct symbol *sym)
 130 {
 131         const char *key;
 132
 133         return get_param_key_from_var_sym(name, sym, NULL, &key) >= 0;
 134 }
 135
 136 static void mark_matches_as_undefined(const char *key)
 137 {
 138         struct sm_state *sm;
 139         int start_pos, state_len, key_len;
 140         char *p;
 141
 142         while ((p = strchr(key, '-'))) {
 143                 if (p[1] != '>')
 144                         return;
 145                 key = p + 2;
 146         }
 147         key_len = strlen(key);
 148
 149         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 150                 state_len = strlen(sm->name);
 151                 if (state_len < key_len)
 152                         continue;
 153                 if (!slist_has_state(sm->possible, &alloc))
 154                         continue;
 155
 156                 start_pos = state_len - key_len;
 157                 if ((start_pos == 0 || !isalnum(sm->name[start_pos - 1])) &&
 158                     strcmp(sm->name + start_pos, key) == 0)
 159                         set_state(my_id, sm->name, sm->sym, &undefined);
 160
 161         } END_FOR_EACH_SM(sm);
 162 }
 163
 164 static bool is_alloc_primitive(struct expression *expr)
 165 {
 166         int i;
 167
 168         while (expr->type == EXPR_ASSIGNMENT)
 169                 expr = strip_expr(expr->right);
 170         if (expr->type != EXPR_CALL)
 171                 return false;
 172
 173         if (expr->fn->type != EXPR_SYMBOL)
 174                 return false;
 175
 176         for (i = 0; i < ARRAY_SIZE(func_table); i++) {
 177                 if (sym_name_is(func_table[i].name, expr->fn))
 178                         return true;
 179         }
 180
 181         return false;
 182 }
 183
 184 static void return_param_alloc(struct expression *expr, const char *name, struct symbol *sym, void *data)
 185 {
 186         fn_has_alloc = true;
 187         set_state(my_id, name, sym, &alloc);
 188 }
 189
 190 static void return_param_release(struct expression *expr, const char *name, struct symbol *sym, void *data)
 191 {
 192         struct sm_state *start_sm;
 193
 194         /* The !data means this comes from the DB (not hard coded). */
 195         if (!data && is_alloc_primitive(expr))
 196                 return;
 197
 198         start_sm = get_start_sm(name, sym);
 199         if (!start_sm) {
 200                 if (fn_has_alloc) {
 201                         mark_matches_as_undefined(name);
 202                         return;
 203                 }
 204                 if (is_param_var_sym(name, sym))
 205                         set_state(my_id, name, sym, &param_released);
 206                 return;
 207         }
 208
 209         if (start_sm)
 210                 set_state(my_id, start_sm->name, start_sm->sym, &release);
 211         else
 212                 set_state(my_id, name, sym, &release);
 213 }
 214
 215 static void ignore_path(const char *fn, struct expression *expr, void *data)
 216 {
 217         set_state(my_id, "path", NULL, &ignore);
 218 }
 219
 220 static void match_return_info(int return_id, char *return_ranges, struct expression *expr)
 221 {
 222         struct sm_state *sm;
 223         const char *param_name;
 224         int param;
 225
 226         if (is_impossible_path())
 227                 return;
 228
 229         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 230                 if (sm->state != &param_released)
 231                         continue;
 232                 param = get_param_key_from_sm(sm, expr, &param_name);
 233                 if (param < 0)
 234                         continue;
 235                 sql_insert_return_states(return_id, return_ranges, RELEASE,
 236                                          param, param_name, "");
 237         } END_FOR_EACH_SM(sm);
 238 }
 239
 240 enum {
 241         UNKNOWN, FAIL, SUCCESS, NUM_BUCKETS
 242 };
 243
 244 static int success_fail_positive(struct range_list *rl)
 245 {
 246         if (!rl)
 247                 return UNKNOWN;
 248
 249         if (sval_is_negative(rl_min(rl)) && sval_is_negative(rl_max(rl)))
 250                 return FAIL;
 251
 252         if (rl_min(rl).value == 0)
 253                 return SUCCESS;
 254
 255         return UNKNOWN;
 256 }
 257
 258 static void check_balance(const char *name, struct symbol *sym)
 259 {
 260         struct range_list *inc_lines = NULL;
 261         int inc_buckets[NUM_BUCKETS] = {};
 262         struct stree *stree, *orig_stree;
 263         struct smatch_state *state;
 264         struct sm_state *return_sm;
 265         struct sm_state *sm;
 266         sval_t line = sval_type_val(&int_ctype, 0);
 267         int bucket;
 268
 269         FOR_EACH_PTR(get_all_return_strees(), stree) {
 270                 orig_stree = __swap_cur_stree(stree);
 271
 272                 if (is_impossible_path())
 273                         goto swap_stree;
 274                 if (db_incomplete())
 275                         goto swap_stree;
 276                 if (get_state(my_id, "path", NULL) == &ignore)
 277                         goto swap_stree;
 278
 279                 return_sm = get_sm_state(RETURN_ID, "return_ranges", NULL);
 280                 if (!return_sm)
 281                         goto swap_stree;
 282                 line.value = return_sm->line;
 283
 284                 sm = get_sm_state(my_id, name, sym);
 285                 if (!sm)
 286                         goto swap_stree;
 287
 288                 state = sm->state;
 289                 if (state == &param_released)
 290                         state = &release;
 291
 292                 if (state != &alloc &&
 293                     state != &release)
 294                         goto swap_stree;
 295
 296                 bucket = success_fail_positive(estate_rl(return_sm->state));
 297                 if (bucket != FAIL)
 298                         goto swap_stree;
 299
 300                 if (state == &alloc) {
 301                         add_range(&inc_lines, line, line);
 302                         inc_buckets[bucket] = true;
 303                 }
 304 swap_stree:
 305                 __swap_cur_stree(orig_stree);
 306         } END_FOR_EACH_PTR(stree);
 307
 308         if (inc_buckets[FAIL])
 309                 goto complain;
 310
 311         return;
 312
 313 complain:
 314         sm_warning("'%s' not released on lines: %s.", name, show_rl(inc_lines));
 315 }
 316
 317 static void match_check_balanced(struct symbol *sym)
 318 {
 319         struct sm_state *sm;
 320
 321         FOR_EACH_MY_SM(my_id, get_all_return_states(), sm) {
 322                 if (sm->sym == NULL && strcmp(sm->name, "path") == 0)
 323                         continue;
 324                 check_balance(sm->name, sm->sym);
 325         } END_FOR_EACH_SM(sm);
 326 }
 327
 328 void check_unwind(int id)
 329 {
 330         struct ref_func_info *info;
 331         int i;
 332
 333         my_id = id;
 334
 335         if (option_project != PROJ_KERNEL)
 336                 return;
 337
 338         for (i = 0; i < ARRAY_SIZE(func_table); i++) {
 339                 info = &func_table[i];
 340
 341                 if (info->call_back) {
 342                         add_function_hook(info->name, info->call_back, info);
 343                 } else if (info->implies_start && info->type == ALLOC) {
 344                         return_implies_param_key_exact(info->name,
 345                                         *info->implies_start,
 346                                         *info->implies_end,
 347                                         &return_param_alloc,
 348                                         info->param, info->key, info);
 349                 } else if (info->implies_start) {
 350                         return_implies_param_key(info->name,
 351                                         *info->implies_start,
 352                                         *info->implies_end,
 353                                         &return_param_release,
 354                                         info->param, info->key, info);
 355                 } else {
 356                         add_function_param_key_hook(info->name,
 357                                 (info->type == ALLOC) ? &return_param_alloc : &return_param_release,
 358                                 info->param, info->key, info);
 359                 }
 360         }
 361
 362         add_function_hook("devm_add_action_or_reset", &ignore_path, NULL);
 363
 364         add_unmatched_state_hook(my_id, &unmatched_state);
 365         add_function_data(&fn_has_alloc);
 366
 367         add_split_return_callback(match_return_info);
 368         select_return_param_key(RELEASE, &return_param_release);
 369         add_hook(&match_check_balanced, END_FUNC_HOOK);
 370 }