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                 *rl = cast_rl(get_type(arg), *rl);
  47         }
  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
 273
 274 static void find_module_init_exit(struct symbol_list *sym_list)
 275 {
 276         struct symbol *sym;
 277         struct symbol *fn;
 278         struct statement *stmt;
 279         char *name;
 280         int init;
 281         int count;
 282
 283         /*
 284          * This is more complicated because Sparse ignores the "alias"
 285          * attribute.  I search backwards because module_init() is normally at
 286          * the end of the file.
 287          */
 288         count = 0;
 289         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 290                 if (sym->type != SYM_NODE)
 291                         continue;
 292                 if (!(sym->ctype.modifiers & MOD_STATIC))
 293                         continue;
 294                 fn = get_base_type(sym);
 295                 if (!fn)
 296                         continue;
 297                 if (fn->type != SYM_FN)
 298                         continue;
 299                 if (!sym->ident)
 300                         continue;
 301                 if (!fn->inline_stmt)
 302                         continue;
 303                 if (strcmp(sym->ident->name, "__inittest") == 0)
 304                         init = 1;
 305                 else if (strcmp(sym->ident->name, "__exittest") == 0)
 306                         init = 0;
 307                 else
 308                         continue;
 309
 310                 count++;
 311
 312                 stmt = first_ptr_list((struct ptr_list *)fn->inline_stmt->stmts);
 313                 if (!stmt || stmt->type != STMT_RETURN)
 314                         continue;
 315                 name = expr_to_var(stmt->ret_value);
 316                 if (!name)
 317                         continue;
 318                 if (init)
 319                         sql_insert_function_ptr(name, "(struct module)->init");
 320                 else
 321                         sql_insert_function_ptr(name, "(struct module)->exit");
 322                 free_string(name);
 323                 if (count >= 2)
 324                         return;
 325         } END_FOR_EACH_PTR_REVERSE(sym);
 326 }
 327
 328 static void match_end_file(struct symbol_list *sym_list)
 329 {
 330         struct symbol *sym;
 331
 332         /* find the last static symbol in the file */
 333         FOR_EACH_PTR_REVERSE(sym_list, sym) {
 334                 if (!(sym->ctype.modifiers & MOD_STATIC))
 335                         continue;
 336                 if (!sym->scope)
 337                         continue;
 338                 find_module_init_exit(sym->scope->symbols);
 339                 return;
 340         } END_FOR_EACH_PTR_REVERSE(sym);
 341 }
 342
 343 static struct expression *get_val_expr(struct expression *expr)
 344 {
 345         struct symbol *sym, *val;
 346
 347         if (expr->type != EXPR_DEREF)
 348                 return NULL;
 349         expr = expr->deref;
 350         if (expr->type != EXPR_SYMBOL)
 351                 return NULL;
 352         if (strcmp(expr->symbol_name->name, "__u") != 0)
 353                 return NULL;
 354         sym = get_base_type(expr->symbol);
 355         val = first_ptr_list((struct ptr_list *)sym->symbol_list);
 356         if (!val || strcmp(val->ident->name, "__val") != 0)
 357                 return NULL;
 358         return member_expression(expr, '.', val->ident);
 359 }
 360
 361 static void match__write_once_size(const char *fn, struct expression *call,
 362                                void *unused)
 363 {
 364         struct expression *dest, *data, *assign;
 365         struct range_list *rl;
 366
 367         dest = get_argument_from_call_expr(call->args, 0);
 368         if (dest->type != EXPR_PREOP || dest->op != '&')
 369                 return;
 370         dest = strip_expr(dest->unop);
 371
 372         data = get_argument_from_call_expr(call->args, 1);
 373         data = get_val_expr(data);
 374         if (!data)
 375                 return;
 376         get_absolute_rl(data, &rl);
 377         assign = assign_expression(dest, '=', data);
 378
 379         __in_fake_assign++;
 380         __split_expr(assign);
 381         __in_fake_assign--;
 382 }
 383
 384 static void match__read_once_size(const char *fn, struct expression *call,
 385                                void *unused)
 386 {
 387         struct expression *dest, *data, *assign;
 388         struct symbol *type, *val_sym;
 389
 390         /*
 391          * We want to change:
 392          *      __read_once_size_nocheck(&(x), __u.__c, sizeof(x));
 393          * into a fake assignment:
 394          *      __u.val = x;
 395          *
 396          */
 397
 398         data = get_argument_from_call_expr(call->args, 0);
 399         if (data->type != EXPR_PREOP || data->op != '&')
 400                 return;
 401         data = strip_parens(data->unop);
 402
 403         dest = get_argument_from_call_expr(call->args, 1);
 404         if (dest->type != EXPR_DEREF || dest->op != '.')
 405                 return;
 406         if (!dest->member || strcmp(dest->member->name, "__c") != 0)
 407                 return;
 408         dest = dest->deref;
 409         type = get_type(dest);
 410         if (!type)
 411                 return;
 412         val_sym = first_ptr_list((struct ptr_list *)type->symbol_list);
 413         dest = member_expression(dest, '.', val_sym->ident);
 414
 415         assign = assign_expression(dest, '=', data);
 416         __in_fake_assign++;
 417         __split_expr(assign);
 418         __in_fake_assign--;
 419 }
 420
 421 bool is_ignored_kernel_data(const char *name)
 422 {
 423         if (option_project != PROJ_KERNEL)
 424                 return false;
 425
 426         /*
 427          * On the file I was looking at lockdep was 25% of the DB.
 428          */
 429         if (strstr(name, ".dep_map."))
 430                 return true;
 431         if (strstr(name, ".lockdep_map."))
 432                 return true;
 433         return false;
 434 }
 435
 436 void check_kernel(int id)
 437 {
 438         if (option_project != PROJ_KERNEL)
 439                 return;
 440
 441         err_ptr_min = sval_cast(&ptr_ctype, err_ptr_min);
 442         err_ptr_max = sval_cast(&ptr_ctype, err_ptr_max);
 443
 444         add_implied_return_hook("ERR_PTR", &implied_err_cast_return, NULL);
 445         add_implied_return_hook("ERR_CAST", &implied_err_cast_return, NULL);
 446         add_implied_return_hook("PTR_ERR", &implied_err_cast_return, NULL);
 447         add_hook(hack_ERR_PTR, AFTER_DEF_HOOK);
 448         return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_param_valid_ptr, (void *)0);
 449         return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_param_err_or_null, (void *)0);
 450         return_implies_state("IS_ERR", 0, 0, &match_not_err, NULL);
 451         return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
 452         return_implies_state("tomoyo_memory_ok", 1, 1, &match_param_valid_ptr, (void *)0);
 453
 454         add_macro_assign_hook_extra("container_of", &match_container_of_macro, NULL);
 455         add_hook(match_container_of, ASSIGNMENT_HOOK);
 456
 457         add_implied_return_hook("find_next_bit", &match_next_bit, NULL);
 458         add_implied_return_hook("find_next_zero_bit", &match_next_bit, NULL);
 459         add_implied_return_hook("find_first_bit", &match_next_bit, NULL);
 460         add_implied_return_hook("find_first_zero_bit", &match_next_bit, NULL);
 461
 462         add_implied_return_hook("fls", &match_fls, NULL);
 463         add_implied_return_hook("fls64", &match_fls, NULL);
 464
 465         add_function_hook("__ftrace_bad_type", &__match_nullify_path_hook, NULL);
 466         add_function_hook("__write_once_size", &match__write_once_size, NULL);
 467
 468         add_function_hook("__read_once_size", &match__read_once_size, NULL);
 469         add_function_hook("__read_once_size_nocheck", &match__read_once_size, NULL);
 470
 471         if (option_info)
 472                 add_hook(match_end_file, END_FILE_HOOK);
 473 }