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