check_kernel.c

   1 /*
   2  * Copyright (C) 2010 Dan Carpenter.
   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 kernel specific stuff for smatch_extra.
  20  */
  21
  22 #include "scope.h"
  23 #include "smatch.h"
  24 #include "smatch_extra.h"
  25
  26 static sval_t err_ptr_min = {
  27         .type = &ptr_ctype,
  28         .value = -4095,
  29 };
  30 static sval_t err_ptr_max = {
  31         .type = &ptr_ctype,
  32         .value = -1,
  33 };
  34 static sval_t null_ptr = {
  35         .type = &ptr_ctype,
  36         .value = 0,
  37 };
  38
  39 static int implied_err_cast_return(struct expression *call, void *unused, struct range_list **rl)
  40 {
  41         struct expression *arg;
  42
  43         arg = get_argument_from_call_expr(call->args, 0);
  44         if (!get_implied_rl(arg, rl))
  45                 *rl = alloc_rl(err_ptr_min, err_ptr_max);
  46
  47         *rl = cast_rl(get_type(call), *rl);
  48         return 1;
  49 }
  50
  51 static void hack_ERR_PTR(struct symbol *sym)
  52 {
  53         struct symbol *arg;
  54         struct smatch_state *estate;
  55         struct range_list *after;
  56         sval_t low_error = {
  57                 .type = &long_ctype,
  58                 .value = -4095,
  59         };
  60         sval_t minus_one = {
  61                 .type = &long_ctype,
  62                 .value = -1,
  63         };
  64         sval_t zero = {
  65                 .type = &long_ctype,
  66                 .value = 0,
  67         };
  68
  69         if (!sym || !sym->ident)
  70                 return;
  71         if (strcmp(sym->ident->name, "ERR_PTR") != 0)
  72                 return;
  73
  74         arg = first_ptr_list((struct ptr_list *)sym->ctype.base_type->arguments);
  75         if (!arg || !arg->ident)
  76                 return;
  77
  78         estate = get_state(SMATCH_EXTRA, arg->ident->name, arg);
  79         if (!estate) {
  80                 after = alloc_rl(low_error, minus_one);
  81         } else {
  82                 after = rl_intersection(estate_rl(estate), alloc_rl(low_error, zero));
  83                 if (rl_equiv(estate_rl(estate), after))
  84                         return;
  85         }
  86         set_state(SMATCH_EXTRA, arg->ident->name, arg, alloc_estate_rl(after));
  87 }
  88
  89 static void match_param_valid_ptr(const char *fn, struct expression *call_expr,
  90                         struct expression *assign_expr, void *_param)
  91 {
  92         int param = PTR_INT(_param);
  93         struct expression *arg;
  94         struct smatch_state *pre_state;
  95         struct smatch_state *end_state;
  96         struct range_list *rl;
  97
  98         arg = get_argument_from_call_expr(call_expr->args, param);
  99         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 100         if (estate_rl(pre_state)) {
 101                 rl = estate_rl(pre_state);
 102                 rl = remove_range(rl, null_ptr, null_ptr);
 103                 rl = remove_range(rl, err_ptr_min, err_ptr_max);
 104         } else {
 105                 rl = alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
 106         }
 107         end_state = alloc_estate_rl(rl);
 108         set_extra_expr_nomod(arg, end_state);
 109 }
 110
 111 static void match_param_err_or_null(const char *fn, struct expression *call_expr,
 112                         struct expression *assign_expr, void *_param)
 113 {
 114         int param = PTR_INT(_param);
 115         struct expression *arg;
 116         struct range_list *pre, *rl;
 117         struct smatch_state *pre_state;
 118         struct smatch_state *end_state;
 119
 120         arg = get_argument_from_call_expr(call_expr->args, param);
 121         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 122         if (pre_state)
 123                 pre = estate_rl(pre_state);
 124         else
 125                 pre = alloc_whole_rl(&ptr_ctype);
 126         call_results_to_rl(call_expr, &ptr_ctype, "0,(-4095)-(-1)", &rl);
 127         rl = rl_intersection(pre, rl);
 128         rl = cast_rl(get_type(arg), rl);
 129         end_state = alloc_estate_rl(rl);
 130         set_extra_expr_nomod(arg, end_state);
 131 }
 132
 133 static void match_not_err(const char *fn, struct expression *call_expr,
 134                         struct expression *assign_expr, void *unused)
 135 {
 136         struct expression *arg;
 137         struct smatch_state *pre_state;
 138         struct range_list *rl;
 139
 140         arg = get_argument_from_call_expr(call_expr->args, 0);
 141         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 142         if (pre_state)
 143                 return;
 144         rl = alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
 145         rl = cast_rl(get_type(arg), rl);
 146         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 147 }
 148
 149 static void match_err(const char *fn, struct expression *call_expr,
 150                         struct expression *assign_expr, void *unused)
 151 {
 152         struct expression *arg;
 153         struct smatch_state *pre_state;
 154         struct range_list *rl;
 155
 156         arg = get_argument_from_call_expr(call_expr->args, 0);
 157         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 158         rl = estate_rl(pre_state);
 159         if (!rl)
 160                 rl = alloc_rl(err_ptr_min, err_ptr_max);
 161         rl = rl_intersection(rl, alloc_rl(err_ptr_min, err_ptr_max));
 162         rl = cast_rl(get_type(arg), rl);
 163         if (pre_state && rl) {
 164                 /*
 165                  * Ideally this would all be handled by smatch_implied.c
 166                  * but it doesn't work very well for impossible paths.
 167                  *
 168                  */
 169                 return;
 170         }
 171         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 172 }
 173
 174 static void match_container_of_macro(const char *fn, struct expression *expr, void *unused)
 175 {
 176         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 177 }
 178
 179 static void match_container_of(struct expression *expr)
 180 {
 181         struct expression *right = expr->right;
 182         char *macro;
 183
 184         /*
 185          * The problem here is that sometimes the container_of() macro is itself
 186          * inside a macro and get_macro() only returns the name of the outside
 187          * macro.
 188          */
 189
 190         /*
 191          * This actually an expression statement assignment but smatch_flow
 192          * pre-mangles it for us so we only get the last chunk:
 193          * sk = (typeof(sk))((char *)__mptr - offsetof(...))
 194          */
 195
 196         macro = get_macro_name(right->pos);
 197         if (!macro)
 198                 return;
 199         if (right->type != EXPR_CAST)
 200                 return;
 201         right = strip_expr(right);
 202         if (right->type != EXPR_BINOP || right->op != '-' ||
 203             right->left->type != EXPR_CAST)
 204                 return;
 205         right = strip_expr(right->left);
 206         if (right->type != EXPR_SYMBOL)
 207                 return;
 208         if (!right->symbol->ident ||
 209             strcmp(right->symbol->ident->name, "__mptr") != 0)
 210                 return;
 211         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 212 }
 213
 214 static int match_next_bit(struct expression *call, void *unused, struct range_list **rl)
 215 {
 216         struct expression *start_arg;
 217         struct expression *size_arg;
 218         struct symbol *type;
 219         sval_t min, max, tmp;
 220
 221         size_arg = get_argument_from_call_expr(call->args, 1);
 222         /* btw. there isn't a start_arg for find_first_bit() */
 223         start_arg = get_argument_from_call_expr(call->args, 2);
 224
 225         type = get_type(call);
 226         min = sval_type_val(type, 0);
 227         max = sval_type_val(type, sizeof(long long) * 8);
 228
 229         if (get_implied_max(size_arg, &tmp) && tmp.uvalue < max.value)
 230                 max = tmp;
 231         if (start_arg && get_implied_min(start_arg, &tmp) && !sval_is_negative(tmp))
 232                 min = tmp;
 233         if (sval_cmp(min, max) > 0)
 234                 max = min;
 235         min = sval_cast(type, min);
 236         max = sval_cast(type, max);
 237         *rl = alloc_rl(min, max);
 238         return 1;
 239 }
 240
 241 static int match_fls(struct expression *call, void *unused, struct range_list **rl)
 242 {
 243         struct expression *arg;
 244         struct range_list *arg_rl;
 245         sval_t zero = {};
 246         sval_t start = {
 247                 .type = &int_ctype,
 248                 .value = 0,
 249         };
 250         sval_t end = {
 251                 .type = &int_ctype,
 252                 .value = 32,
 253         };
 254         sval_t sval;
 255
 256         arg = get_argument_from_call_expr(call->args, 0);
 257         if (!get_implied_rl(arg, &arg_rl))
 258                 return 0;
 259         if (rl_to_sval(arg_rl, &sval)) {
 260                 int i;
 261
 262                 for (i = 63; i >= 0; i--) {
 263                         if (sval.uvalue & 1ULL << i)
 264                                 break;
 265                 }
 266                 sval.value = i + 1;
 267                 *rl = alloc_rl(sval, sval);
 268                 return 1;
 269         }
 270         zero.type = rl_type(arg_rl);
 271         if (!rl_has_sval(arg_rl, zero))
 272                 start.value = 1;
 273         *rl = alloc_rl(start, end);
 274         return 1;
 275 }
 276
 277 static void find_module_init_exit(struct symbol_list *sym_list)
 278 {
 279         struct symbol *sym;
 280         struct symbol *fn;
 281         struct statement *stmt;
 282         char *name;
 283         int init;
 284         int count;
 285
 286         /*
 287          * This is more complicated because Sparse ignores the "alias"
 288          * attribute.  I search backwards because module_init() is normally at
 289          * the end of the file.
 290          */
 291         count = 0;
 292         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 293                 if (sym->type != SYM_NODE)
 294                         continue;
 295                 if (!(sym->ctype.modifiers & MOD_STATIC))
 296                         continue;
 297                 fn = get_base_type(sym);
 298                 if (!fn)
 299                         continue;
 300                 if (fn->type != SYM_FN)
 301                         continue;
 302                 if (!sym->ident)
 303                         continue;
 304                 if (!fn->inline_stmt)
 305                         continue;
 306                 if (strcmp(sym->ident->name, "__inittest") == 0)
 307                         init = 1;
 308                 else if (strcmp(sym->ident->name, "__exittest") == 0)
 309                         init = 0;
 310                 else
 311                         continue;
 312
 313                 count++;
 314
 315                 stmt = first_ptr_list((struct ptr_list *)fn->inline_stmt->stmts);
 316                 if (!stmt || stmt->type != STMT_RETURN)
 317                         continue;
 318                 name = expr_to_var(stmt->ret_value);
 319                 if (!name)
 320                         continue;
 321                 if (init)
 322                         sql_insert_function_ptr(name, "(struct module)->init");
 323                 else
 324                         sql_insert_function_ptr(name, "(struct module)->exit");
 325                 free_string(name);
 326                 if (count >= 2)
 327                         return;
 328         } END_FOR_EACH_PTR_REVERSE(sym);
 329 }
 330
 331 static void match_end_file(struct symbol_list *sym_list)
 332 {
 333         struct symbol *sym;
 334
 335         /* find the last static symbol in the file */
 336         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 337                 if (!(sym->ctype.modifiers & MOD_STATIC))
 338                         continue;
 339                 if (!sym->scope)
 340                         continue;
 341                 find_module_init_exit(sym->scope->symbols);
 342                 return;
 343         } END_FOR_EACH_PTR_REVERSE(sym);
 344 }
 345
 346 static struct expression *get_val_expr(struct expression *expr)
 347 {
 348         struct symbol *sym, *val;
 349
 350         if (expr->type != EXPR_DEREF)
 351                 return NULL;
 352         expr = expr->deref;
 353         if (expr->type != EXPR_SYMBOL)
 354                 return NULL;
 355         if (strcmp(expr->symbol_name->name, "__u") != 0)
 356                 return NULL;
 357         sym = get_base_type(expr->symbol);
 358         val = first_ptr_list((struct ptr_list *)sym->symbol_list);
 359         if (!val || strcmp(val->ident->name, "__val") != 0)
 360                 return NULL;
 361         return member_expression(expr, '.', val->ident);
 362 }
 363
 364 static void match__write_once_size(const char *fn, struct expression *call,
 365                                void *unused)
 366 {
 367         struct expression *dest, *data, *assign;
 368         struct range_list *rl;
 369
 370         dest = get_argument_from_call_expr(call->args, 0);
 371         if (dest->type != EXPR_PREOP || dest->op != '&')
 372                 return;
 373         dest = strip_expr(dest->unop);
 374
 375         data = get_argument_from_call_expr(call->args, 1);
 376         data = get_val_expr(data);
 377         if (!data)
 378                 return;
 379         get_absolute_rl(data, &rl);
 380         assign = assign_expression(dest, '=', data);
 381
 382         __in_fake_assign++;
 383         __split_expr(assign);
 384         __in_fake_assign--;
 385 }
 386
 387 static void match__read_once_size(const char *fn, struct expression *call,
 388                                void *unused)
 389 {
 390         struct expression *dest, *data, *assign;
 391         struct symbol *type, *val_sym;
 392
 393         /*
 394          * We want to change:
 395          *      __read_once_size_nocheck(&(x), __u.__c, sizeof(x));
 396          * into a fake assignment:
 397          *      __u.val = x;
 398          *
 399          */
 400
 401         data = get_argument_from_call_expr(call->args, 0);
 402         if (data->type != EXPR_PREOP || data->op != '&')
 403                 return;
 404         data = strip_parens(data->unop);
 405
 406         dest = get_argument_from_call_expr(call->args, 1);
 407         if (dest->type != EXPR_DEREF || dest->op != '.')
 408                 return;
 409         if (!dest->member || strcmp(dest->member->name, "__c") != 0)
 410                 return;
 411         dest = dest->deref;
 412         type = get_type(dest);
 413         if (!type)
 414                 return;
 415         val_sym = first_ptr_list((struct ptr_list *)type->symbol_list);
 416         dest = member_expression(dest, '.', val_sym->ident);
 417
 418         assign = assign_expression(dest, '=', data);
 419         __in_fake_assign++;
 420         __split_expr(assign);
 421         __in_fake_assign--;
 422 }
 423
 424 static void match_closure_call(const char *name, struct expression *call,
 425                                void *unused)
 426 {
 427         struct expression *cl, *fn, *fake_call;
 428         struct expression_list *args = NULL;
 429
 430         cl = get_argument_from_call_expr(call->args, 0);
 431         fn = get_argument_from_call_expr(call->args, 1);
 432         if (!fn || !cl)
 433                 return;
 434
 435         add_ptr_list(&args, cl);
 436         fake_call = call_expression(fn, args);
 437         __split_expr(fake_call);
 438 }
 439
 440 bool is_ignored_kernel_data(const char *name)
 441 {
 442         if (option_project != PROJ_KERNEL)
 443                 return false;
 444
 445         /*
 446          * On the file I was looking at lockdep was 25% of the DB.
 447          */
 448         if (strstr(name, ".dep_map."))
 449                 return true;
 450         if (strstr(name, ".lockdep_map."))
 451                 return true;
 452         return false;
 453 }
 454
 455 void check_kernel(int id)
 456 {
 457         if (option_project != PROJ_KERNEL)
 458                 return;
 459
 460         err_ptr_min = sval_cast(&ptr_ctype, err_ptr_min);
 461         err_ptr_max = sval_cast(&ptr_ctype, err_ptr_max);
 462
 463         add_implied_return_hook("ERR_PTR", &implied_err_cast_return, NULL);
 464         add_implied_return_hook("ERR_CAST", &implied_err_cast_return, NULL);
 465         add_implied_return_hook("PTR_ERR", &implied_err_cast_return, NULL);
 466         add_hook(hack_ERR_PTR, AFTER_DEF_HOOK);
 467         return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_param_valid_ptr, (void *)0);
 468         return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_param_err_or_null, (void *)0);
 469         return_implies_state("IS_ERR", 0, 0, &match_not_err, NULL);
 470         return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
 471         return_implies_state("tomoyo_memory_ok", 1, 1, &match_param_valid_ptr, (void *)0);
 472
 473         add_macro_assign_hook_extra("container_of", &match_container_of_macro, NULL);
 474         add_hook(match_container_of, ASSIGNMENT_HOOK);
 475
 476         add_implied_return_hook("find_next_bit", &match_next_bit, NULL);
 477         add_implied_return_hook("find_next_zero_bit", &match_next_bit, NULL);
 478         add_implied_return_hook("find_first_bit", &match_next_bit, NULL);
 479         add_implied_return_hook("find_first_zero_bit", &match_next_bit, NULL);
 480
 481         add_implied_return_hook("fls", &match_fls, NULL);
 482         add_implied_return_hook("fls64", &match_fls, NULL);
 483
 484         add_function_hook("__ftrace_bad_type", &__match_nullify_path_hook, NULL);
 485         add_function_hook("__write_once_size", &match__write_once_size, NULL);
 486
 487         add_function_hook("__read_once_size", &match__read_once_size, NULL);
 488         add_function_hook("__read_once_size_nocheck", &match__read_once_size, NULL);
 489
 490         add_function_hook("closure_call", &match_closure_call, NULL);
 491
 492         if (option_info)
 493                 add_hook(match_end_file, END_FILE_HOOK);
 494 }