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 (estate_rl(pre_state)) {
 143                 rl = estate_rl(pre_state);
 144                 rl = remove_range(rl, err_ptr_min, err_ptr_max);
 145         } else {
 146                 rl = alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
 147         }
 148         rl = cast_rl(get_type(arg), rl);
 149         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 150 }
 151
 152 static void match_err(const char *fn, struct expression *call_expr,
 153                         struct expression *assign_expr, void *unused)
 154 {
 155         struct expression *arg;
 156         struct smatch_state *pre_state;
 157         struct range_list *rl;
 158
 159         arg = get_argument_from_call_expr(call_expr->args, 0);
 160         pre_state = get_state_expr(SMATCH_EXTRA, arg);
 161         rl = estate_rl(pre_state);
 162         if (!rl)
 163                 rl = alloc_rl(err_ptr_min, err_ptr_max);
 164         rl = rl_intersection(rl, alloc_rl(err_ptr_min, err_ptr_max));
 165         rl = cast_rl(get_type(arg), rl);
 166         set_extra_expr_nomod(arg, alloc_estate_rl(rl));
 167 }
 168
 169 static void match_container_of_macro(const char *fn, struct expression *expr, void *unused)
 170 {
 171         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 172 }
 173
 174 static void match_container_of(struct expression *expr)
 175 {
 176         struct expression *right = expr->right;
 177         char *macro;
 178
 179         /*
 180          * The problem here is that sometimes the container_of() macro is itself
 181          * inside a macro and get_macro() only returns the name of the outside
 182          * macro.
 183          */
 184
 185         /*
 186          * This actually an expression statement assignment but smatch_flow
 187          * pre-mangles it for us so we only get the last chunk:
 188          * sk = (typeof(sk))((char *)__mptr - offsetof(...))
 189          */
 190
 191         macro = get_macro_name(right->pos);
 192         if (!macro)
 193                 return;
 194         if (right->type != EXPR_CAST)
 195                 return;
 196         right = strip_expr(right);
 197         if (right->type != EXPR_BINOP || right->op != '-' ||
 198             right->left->type != EXPR_CAST)
 199                 return;
 200         right = strip_expr(right->left);
 201         if (right->type != EXPR_SYMBOL)
 202                 return;
 203         if (!right->symbol->ident ||
 204             strcmp(right->symbol->ident->name, "__mptr") != 0)
 205                 return;
 206         set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
 207 }
 208
 209 static int match_next_bit(struct expression *call, void *unused, struct range_list **rl)
 210 {
 211         struct expression *start_arg;
 212         struct expression *size_arg;
 213         struct symbol *type;
 214         sval_t min, max, tmp;
 215
 216         size_arg = get_argument_from_call_expr(call->args, 1);
 217         /* btw. there isn't a start_arg for find_first_bit() */
 218         start_arg = get_argument_from_call_expr(call->args, 2);
 219
 220         type = get_type(call);
 221         min = sval_type_val(type, 0);
 222         max = sval_type_val(type, sizeof(long long) * 8);
 223
 224         if (get_implied_max(size_arg, &tmp) && tmp.uvalue < max.value)
 225                 max = tmp;
 226         if (start_arg && get_implied_min(start_arg, &tmp) && !sval_is_negative(tmp))
 227                 min = tmp;
 228         if (sval_cmp(min, max) > 0)
 229                 max = min;
 230         min = sval_cast(type, min);
 231         max = sval_cast(type, max);
 232         *rl = alloc_rl(min, max);
 233         return 1;
 234 }
 235
 236 static int match_fls(struct expression *call, void *unused, struct range_list **rl)
 237 {
 238         struct expression *arg;
 239         struct range_list *arg_rl;
 240         sval_t zero = {};
 241         sval_t start = {
 242                 .type = &int_ctype,
 243                 .value = 0,
 244         };
 245         sval_t end = {
 246                 .type = &int_ctype,
 247                 .value = 32,
 248         };
 249         sval_t sval;
 250
 251         arg = get_argument_from_call_expr(call->args, 0);
 252         if (!get_implied_rl(arg, &arg_rl))
 253                 return 0;
 254         if (rl_to_sval(arg_rl, &sval)) {
 255                 int i;
 256
 257                 for (i = 63; i >= 0; i--) {
 258                         if (sval.uvalue & 1ULL << i)
 259                                 break;
 260                 }
 261                 sval.value = i + 1;
 262                 *rl = alloc_rl(sval, sval);
 263                 return 1;
 264         }
 265         zero.type = rl_type(arg_rl);
 266         if (!rl_has_sval(arg_rl, zero))
 267                 start.value = 1;
 268         *rl = alloc_rl(start, end);
 269         return 1;
 270 }
 271
 272 static void find_module_init_exit(struct symbol_list *sym_list)
 273 {
 274         struct symbol *sym;
 275         struct symbol *fn;
 276         struct statement *stmt;
 277         char *name;
 278         int init;
 279         int count;
 280
 281         /*
 282          * This is more complicated because Sparse ignores the "alias"
 283          * attribute.  I search backwards because module_init() is normally at
 284          * the end of the file.
 285          */
 286         count = 0;
 287         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 288                 if (sym->type != SYM_NODE)
 289                         continue;
 290                 if (!(sym->ctype.modifiers & MOD_STATIC))
 291                         continue;
 292                 fn = get_base_type(sym);
 293                 if (!fn)
 294                         continue;
 295                 if (fn->type != SYM_FN)
 296                         continue;
 297                 if (!sym->ident)
 298                         continue;
 299                 if (!fn->inline_stmt)
 300                         continue;
 301                 if (strcmp(sym->ident->name, "__inittest") == 0)
 302                         init = 1;
 303                 else if (strcmp(sym->ident->name, "__exittest") == 0)
 304                         init = 0;
 305                 else
 306                         continue;
 307
 308                 count++;
 309
 310                 stmt = first_ptr_list((struct ptr_list *)fn->inline_stmt->stmts);
 311                 if (!stmt || stmt->type != STMT_RETURN)
 312                         continue;
 313                 name = expr_to_var(stmt->ret_value);
 314                 if (!name)
 315                         continue;
 316                 if (init)
 317                         sql_insert_function_ptr(name, "(struct module)->init");
 318                 else
 319                         sql_insert_function_ptr(name, "(struct module)->exit");
 320                 free_string(name);
 321                 if (count >= 2)
 322                         return;
 323         } END_FOR_EACH_PTR_REVERSE(sym);
 324 }
 325
 326 static void match_end_file(struct symbol_list *sym_list)
 327 {
 328         struct symbol *sym;
 329
 330         /* find the last static symbol in the file */
 331         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 332                 if (!(sym->ctype.modifiers & MOD_STATIC))
 333                         continue;
 334                 if (!sym->scope)
 335                         continue;
 336                 find_module_init_exit(sym->scope->symbols);
 337                 return;
 338         } END_FOR_EACH_PTR_REVERSE(sym);
 339 }
 340
 341 static struct expression *get_val_expr(struct expression *expr)
 342 {
 343         struct symbol *sym, *val;
 344
 345         if (expr->type != EXPR_DEREF)
 346                 return NULL;
 347         expr = expr->deref;
 348         if (expr->type != EXPR_SYMBOL)
 349                 return NULL;
 350         if (strcmp(expr->symbol_name->name, "__u") != 0)
 351                 return NULL;
 352         sym = get_base_type(expr->symbol);
 353         val = first_ptr_list((struct ptr_list *)sym->symbol_list);
 354         if (!val || strcmp(val->ident->name, "__val") != 0)
 355                 return NULL;
 356         return member_expression(expr, '.', val->ident);
 357 }
 358
 359 static void match__write_once_size(const char *fn, struct expression *call,
 360                                void *unused)
 361 {
 362         struct expression *dest, *data, *assign;
 363         struct range_list *rl;
 364
 365         dest = get_argument_from_call_expr(call->args, 0);
 366         if (dest->type != EXPR_PREOP || dest->op != '&')
 367                 return;
 368         dest = strip_expr(dest->unop);
 369
 370         data = get_argument_from_call_expr(call->args, 1);
 371         data = get_val_expr(data);
 372         if (!data)
 373                 return;
 374         get_absolute_rl(data, &rl);
 375         assign = assign_expression(dest, '=', data);
 376
 377         __in_fake_assign++;
 378         __split_expr(assign);
 379         __in_fake_assign--;
 380 }
 381
 382 static void match__read_once_size(const char *fn, struct expression *call,
 383                                void *unused)
 384 {
 385         struct expression *dest, *data, *assign;
 386         struct symbol *type, *val_sym;
 387
 388         /*
 389          * We want to change:
 390          *      __read_once_size_nocheck(&(x), __u.__c, sizeof(x));
 391          * into a fake assignment:
 392          *      __u.val = x;
 393          *
 394          */
 395
 396         data = get_argument_from_call_expr(call->args, 0);
 397         if (data->type != EXPR_PREOP || data->op != '&')
 398                 return;
 399         data = strip_parens(data->unop);
 400
 401         dest = get_argument_from_call_expr(call->args, 1);
 402         if (dest->type != EXPR_DEREF || dest->op != '.')
 403                 return;
 404         if (!dest->member || strcmp(dest->member->name, "__c") != 0)
 405                 return;
 406         dest = dest->deref;
 407         type = get_type(dest);
 408         if (!type)
 409                 return;
 410         val_sym = first_ptr_list((struct ptr_list *)type->symbol_list);
 411         dest = member_expression(dest, '.', val_sym->ident);
 412
 413         assign = assign_expression(dest, '=', data);
 414         __in_fake_assign++;
 415         __split_expr(assign);
 416         __in_fake_assign--;
 417 }
 418
 419 static void match_closure_call(const char *name, struct expression *call,
 420                                void *unused)
 421 {
 422         struct expression *cl, *fn, *fake_call;
 423         struct expression_list *args = NULL;
 424
 425         cl = get_argument_from_call_expr(call->args, 0);
 426         fn = get_argument_from_call_expr(call->args, 1);
 427         if (!fn || !cl)
 428                 return;
 429
 430         add_ptr_list(&args, cl);
 431         fake_call = call_expression(fn, args);
 432         __split_expr(fake_call);
 433 }
 434
 435 bool is_ignored_kernel_data(const char *name)
 436 {
 437         if (option_project != PROJ_KERNEL)
 438                 return false;
 439
 440         /*
 441          * On the file I was looking at lockdep was 25% of the DB.
 442          */
 443         if (strstr(name, ".dep_map."))
 444                 return true;
 445         if (strstr(name, ".lockdep_map."))
 446                 return true;
 447         return false;
 448 }
 449
 450 void check_kernel(int id)
 451 {
 452         if (option_project != PROJ_KERNEL)
 453                 return;
 454
 455         err_ptr_min = sval_cast(&ptr_ctype, err_ptr_min);
 456         err_ptr_max = sval_cast(&ptr_ctype, err_ptr_max);
 457
 458         add_implied_return_hook("ERR_PTR", &implied_err_cast_return, NULL);
 459         add_implied_return_hook("ERR_CAST", &implied_err_cast_return, NULL);
 460         add_implied_return_hook("PTR_ERR", &implied_err_cast_return, NULL);
 461         add_hook(hack_ERR_PTR, AFTER_DEF_HOOK);
 462         return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_param_valid_ptr, (void *)0);
 463         return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_param_err_or_null, (void *)0);
 464         return_implies_state("IS_ERR", 0, 0, &match_not_err, NULL);
 465         return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
 466         return_implies_state("tomoyo_memory_ok", 1, 1, &match_param_valid_ptr, (void *)0);
 467
 468         add_macro_assign_hook_extra("container_of", &match_container_of_macro, NULL);
 469         add_hook(match_container_of, ASSIGNMENT_HOOK);
 470
 471         add_implied_return_hook("find_next_bit", &match_next_bit, NULL);
 472         add_implied_return_hook("find_next_zero_bit", &match_next_bit, NULL);
 473         add_implied_return_hook("find_first_bit", &match_next_bit, NULL);
 474         add_implied_return_hook("find_first_zero_bit", &match_next_bit, NULL);
 475
 476         add_implied_return_hook("fls", &match_fls, NULL);
 477         add_implied_return_hook("fls64", &match_fls, NULL);
 478
 479         add_function_hook("__ftrace_bad_type", &__match_nullify_path_hook, NULL);
 480         add_function_hook("__write_once_size", &match__write_once_size, NULL);
 481
 482         add_function_hook("__read_once_size", &match__read_once_size, NULL);
 483         add_function_hook("__read_once_size_nocheck", &match__read_once_size, NULL);
 484
 485         add_function_hook("closure_call", &match_closure_call, NULL);
 486
 487         if (option_info)
 488                 add_hook(match_end_file, END_FILE_HOOK);
 489 }