1 /*
2 * Copyright (C) 2009 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 * There are several types of function hooks:
20 * add_function_hook() - For any time a function is called.
21 * add_function_assign_hook() - foo = the_function().
22 * add_implied_return_hook() - Calculates the implied return value.
23 * add_macro_assign_hook() - foo = the_macro().
24 * return_implies_state() - For when a return value of 1 implies locked
25 * and 0 implies unlocked. etc. etc.
26 *
27 */
28
29 #include <stdlib.h>
30 #include <stdio.h>
31 #include "smatch.h"
32 #include "smatch_slist.h"
33 #include "smatch_extra.h"
34 #include "smatch_function_hashtable.h"
35
36 struct fcall_back {
37 int type;
38 struct data_range *range;
39 union {
40 func_hook *call_back;
41 implication_hook *ranged;
42 implied_return_hook *implied_return;
43 } u;
44 void *info;
45 };
46
47 ALLOCATOR(fcall_back, "call backs");
48 DECLARE_PTR_LIST(call_back_list, struct fcall_back);
49
50 DEFINE_FUNCTION_HASHTABLE_STATIC(callback, struct fcall_back, struct call_back_list);
51 static struct hashtable *func_hash;
52
53 int __in_fake_parameter_assign;
54
55 #define REGULAR_CALL 0
56 #define RANGED_CALL 1
57 #define ASSIGN_CALL 2
58 #define IMPLIED_RETURN 3
59 #define MACRO_ASSIGN 4
60 #define MACRO_ASSIGN_EXTRA 5
61
62 struct return_implies_callback {
63 int type;
64 return_implies_hook *callback;
65 };
66 ALLOCATOR(return_implies_callback, "return_implies callbacks");
67 DECLARE_PTR_LIST(db_implies_list, struct return_implies_callback);
68 static struct db_implies_list *db_return_states_list;
69
70 typedef void (void_fn)(void);
71 DECLARE_PTR_LIST(void_fn_list, void_fn *);
72 static struct void_fn_list *return_states_before;
73 static struct void_fn_list *return_states_after;
74
75 static struct fcall_back *alloc_fcall_back(int type, void *call_back,
76 void *info)
77 {
78 struct fcall_back *cb;
79
80 cb = __alloc_fcall_back(0);
81 cb->type = type;
82 cb->u.call_back = call_back;
83 cb->info = info;
84 return cb;
85 }
86
87 void add_function_hook(const char *look_for, func_hook *call_back, void *info)
88 {
89 struct fcall_back *cb;
90
91 cb = alloc_fcall_back(REGULAR_CALL, call_back, info);
92 add_callback(func_hash, look_for, cb);
93 }
94
95 void add_function_assign_hook(const char *look_for, func_hook *call_back,
96 void *info)
97 {
98 struct fcall_back *cb;
99
100 cb = alloc_fcall_back(ASSIGN_CALL, call_back, info);
101 add_callback(func_hash, look_for, cb);
102 }
103
104 void add_implied_return_hook(const char *look_for,
105 implied_return_hook *call_back,
106 void *info)
107 {
108 struct fcall_back *cb;
109
110 cb = alloc_fcall_back(IMPLIED_RETURN, call_back, info);
111 add_callback(func_hash, look_for, cb);
112 }
113
114 void add_macro_assign_hook(const char *look_for, func_hook *call_back,
115 void *info)
116 {
117 struct fcall_back *cb;
118
119 cb = alloc_fcall_back(MACRO_ASSIGN, call_back, info);
120 add_callback(func_hash, look_for, cb);
121 }
122
123 void add_macro_assign_hook_extra(const char *look_for, func_hook *call_back,
124 void *info)
125 {
126 struct fcall_back *cb;
127
128 cb = alloc_fcall_back(MACRO_ASSIGN_EXTRA, call_back, info);
129 add_callback(func_hash, look_for, cb);
130 }
131
132 void return_implies_state(const char *look_for, long long start, long long end,
133 implication_hook *call_back, void *info)
134 {
135 struct fcall_back *cb;
136
137 cb = alloc_fcall_back(RANGED_CALL, call_back, info);
138 cb->range = alloc_range_perm(ll_to_sval(start), ll_to_sval(end));
139 add_callback(func_hash, look_for, cb);
140 }
141
142 void return_implies_state_sval(const char *look_for, sval_t start, sval_t end,
143 implication_hook *call_back, void *info)
144 {
145 struct fcall_back *cb;
146
147 cb = alloc_fcall_back(RANGED_CALL, call_back, info);
148 cb->range = alloc_range_perm(start, end);
149 add_callback(func_hash, look_for, cb);
150 }
151
152 void select_return_states_hook(int type, return_implies_hook *callback)
153 {
154 struct return_implies_callback *cb = __alloc_return_implies_callback(0);
155
156 cb->type = type;
157 cb->callback = callback;
158 add_ptr_list(&db_return_states_list, cb);
159 }
160
161 void select_return_states_before(void_fn *fn)
162 {
163 void_fn **p = malloc(sizeof(void_fn *));
164 *p = fn;
165 add_ptr_list(&return_states_before, p);
166 }
167
168 void select_return_states_after(void_fn *fn)
169 {
170 void_fn **p = malloc(sizeof(void_fn *));
171 *p = fn;
172 add_ptr_list(&return_states_after, p);
173 }
174
175 static void call_return_states_before_hooks(void)
176 {
177 void_fn **fn;
178
179 FOR_EACH_PTR(return_states_before, fn) {
180 (*fn)();
181 } END_FOR_EACH_PTR(fn);
182 }
183
184 static void call_return_states_after_hooks(struct expression *expr)
185 {
186 void_fn **fn;
187
188 FOR_EACH_PTR(return_states_after, fn) {
189 (*fn)();
190 } END_FOR_EACH_PTR(fn);
191 __pass_to_client(expr, FUNCTION_CALL_HOOK_AFTER_DB);
192 }
193
194 static int call_call_backs(struct call_back_list *list, int type,
195 const char *fn, struct expression *expr)
196 {
197 struct fcall_back *tmp;
198 int handled = 0;
199
200 FOR_EACH_PTR(list, tmp) {
201 if (tmp->type == type) {
202 (tmp->u.call_back)(fn, expr, tmp->info);
203 handled = 1;
204 }
205 } END_FOR_EACH_PTR(tmp);
206
207 return handled;
208 }
209
210 static void call_ranged_call_backs(struct call_back_list *list,
211 const char *fn, struct expression *call_expr,
212 struct expression *assign_expr)
213 {
214 struct fcall_back *tmp;
215
216 FOR_EACH_PTR(list, tmp) {
217 (tmp->u.ranged)(fn, call_expr, assign_expr, tmp->info);
218 } END_FOR_EACH_PTR(tmp);
219 }
220
221 static struct call_back_list *get_same_ranged_call_backs(struct call_back_list *list,
222 struct data_range *drange)
223 {
224 struct call_back_list *ret = NULL;
225 struct fcall_back *tmp;
226
227 FOR_EACH_PTR(list, tmp) {
228 if (tmp->type != RANGED_CALL)
229 continue;
230 if (ranges_equiv(tmp->range, drange))
231 add_ptr_list(&ret, tmp);
232 } END_FOR_EACH_PTR(tmp);
233 return ret;
234 }
235
236 static int in_list_exact_sval(struct range_list *list, struct data_range *drange)
237 {
238 struct data_range *tmp;
239
240 FOR_EACH_PTR(list, tmp) {
241 if (ranges_equiv(tmp, drange))
242 return 1;
243 } END_FOR_EACH_PTR(tmp);
244 return 0;
245 }
246
247 static int assign_ranged_funcs(const char *fn, struct expression *expr,
248 struct call_back_list *call_backs)
249 {
250 struct fcall_back *tmp;
251 struct sm_state *sm;
252 char *var_name;
253 struct symbol *sym;
254 struct smatch_state *estate;
255 struct stree *tmp_stree;
256 struct stree *final_states = NULL;
257 struct range_list *handled_ranges = NULL;
258 struct call_back_list *same_range_call_backs = NULL;
259 struct range_list *rl;
260 int handled = 0;
261
262 if (!call_backs)
263 return 0;
264
265 var_name = expr_to_var_sym(expr->left, &sym);
266 if (!var_name || !sym)
267 goto free;
268
269 FOR_EACH_PTR(call_backs, tmp) {
270 if (tmp->type != RANGED_CALL)
271 continue;
272
273 if (in_list_exact_sval(handled_ranges, tmp->range))
274 continue;
275 __push_fake_cur_stree();
276 tack_on(&handled_ranges, tmp->range);
277
278 same_range_call_backs = get_same_ranged_call_backs(call_backs, tmp->range);
279 call_ranged_call_backs(same_range_call_backs, fn, expr->right, expr);
280 __free_ptr_list((struct ptr_list **)&same_range_call_backs);
281
282 rl = alloc_rl(tmp->range->min, tmp->range->max);
283 rl = cast_rl(get_type(expr->left), rl);
284 estate = alloc_estate_rl(rl);
285 set_extra_mod(var_name, sym, expr->left, estate);
286
287 tmp_stree = __pop_fake_cur_stree();
288 merge_fake_stree(&final_states, tmp_stree);
289 free_stree(&tmp_stree);
290 handled = 1;
291 } END_FOR_EACH_PTR(tmp);
292
293 FOR_EACH_SM(final_states, sm) {
294 __set_sm(sm);
295 } END_FOR_EACH_SM(sm);
296
297 free_stree(&final_states);
298 free:
299 free_string(var_name);
300 return handled;
301 }
302
303 static void call_implies_callbacks(int comparison, struct expression *expr, sval_t sval, int left, struct stree **implied_true, struct stree **implied_false)
304 {
305 struct call_back_list *call_backs;
306 struct fcall_back *tmp;
307 const char *fn;
308 struct data_range *value_range;
309 struct stree *true_states = NULL;
310 struct stree *false_states = NULL;
311 struct stree *tmp_stree;
312
313 *implied_true = NULL;
314 *implied_false = NULL;
315 if (expr->fn->type != EXPR_SYMBOL || !expr->fn->symbol)
316 return;
317 fn = expr->fn->symbol->ident->name;
318 call_backs = search_callback(func_hash, (char *)expr->fn->symbol->ident->name);
319 if (!call_backs)
320 return;
321 value_range = alloc_range(sval, sval);
322
323 /* set true states */
324 __push_fake_cur_stree();
325 FOR_EACH_PTR(call_backs, tmp) {
326 if (tmp->type != RANGED_CALL)
327 continue;
328 if (!true_comparison_range_LR(comparison, tmp->range, value_range, left))
329 continue;
330 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
331 } END_FOR_EACH_PTR(tmp);
332 tmp_stree = __pop_fake_cur_stree();
333 merge_fake_stree(&true_states, tmp_stree);
334 free_stree(&tmp_stree);
335
336 /* set false states */
337 __push_fake_cur_stree();
338 FOR_EACH_PTR(call_backs, tmp) {
339 if (tmp->type != RANGED_CALL)
340 continue;
341 if (!false_comparison_range_LR(comparison, tmp->range, value_range, left))
342 continue;
343 (tmp->u.ranged)(fn, expr, NULL, tmp->info);
344 } END_FOR_EACH_PTR(tmp);
345 tmp_stree = __pop_fake_cur_stree();
346 merge_fake_stree(&false_states, tmp_stree);
347 free_stree(&tmp_stree);
348
349 *implied_true = true_states;
350 *implied_false = false_states;
351 }
352
353 struct db_callback_info {
354 int true_side;
355 int comparison;
356 struct expression *expr;
357 struct range_list *rl;
358 int left;
359 struct stree *stree;
360 struct db_implies_list *callbacks;
361 int prev_return_id;
362 int cull;
363 int has_states;
364 char *ret_str;
365 struct smatch_state *ret_state;
366 struct expression *var_expr;
367 int handled;
368 };
369
370 static void store_return_state(struct db_callback_info *db_info, const char *ret_str, struct smatch_state *state)
371 {
372 db_info->ret_str = alloc_sname(ret_str),
373 db_info->ret_state = state;
374 }
375
376 static bool fake_a_param_assignment(struct expression *expr, const char *return_str, struct smatch_state *orig)
377 {
378 struct expression *arg, *left, *right, *tmp, *fake_assign;
379 char *p;
380 int param;
381 char buf[256];
382 char *str;
383
384 if (expr->type != EXPR_ASSIGNMENT || expr->op != '=')
385 return false;
386 left = expr->left;
387 right = expr->right;
388
389 while (right->type == EXPR_ASSIGNMENT)
390 right = strip_expr(right->right);
391 if (!right || right->type != EXPR_CALL)
392 return false;
393
394 p = strchr(return_str, '[');
395 if (!p)
396 return false;
397
398 p++;
399 if (p[0] == '=' && p[1] == '=')
400 p += 2;
401 if (p[0] != '$')
402 return false;
403
404 snprintf(buf, sizeof(buf), "%s", p);
405
406 p = buf;
407 p += 1;
408 param = strtol(p, &p, 10);
409
410 p = strchr(p, ']');
411 if (!p || *p != ']')
412 return false;
413 *p = '\0';
414
415 arg = get_argument_from_call_expr(right->args, param);
416 if (!arg)
417 return false;
418
419 /* There should be a get_other_name() function which returns an expr */
420 tmp = get_assigned_expr(arg);
421 if (tmp)
422 arg = tmp;
423
424 /*
425 * This is a sanity check to prevent side effects from evaluating stuff
426 * twice.
427 */
428 str = expr_to_chunk_sym_vsl(arg, NULL, NULL);
429 if (!str)
430 return false;
431 free_string(str);
432
433 right = gen_expression_from_key(arg, buf);
434 if (!right) /* Mostly fails for binops like [$0 + 4032] */
435 return false;
436 fake_assign = assign_expression(left, '=', right);
437 __in_fake_parameter_assign++;
438 __split_expr(fake_assign);
439 __in_fake_parameter_assign--;
440
441 /*
442 * If the return is "0-65531[$0->nla_len - 4]" the faked expression
443 * is maybe (-4)-65531 but we know it is in the 0-65531 range so both
444 * parts have to be considered. We use _nomod() because it's not really
445 * another modification, it's just a clarification.
446 *
447 */
448 if (estate_rl(orig)) {
449 struct smatch_state *faked;
450 struct range_list *rl;
451
452 faked = get_extra_state(left);
453 if (estate_rl(faked)) {
454 rl = rl_intersection(estate_rl(faked), estate_rl(orig));
455 if (rl)
456 set_extra_expr_nomod(expr, alloc_estate_rl(rl));
457 }
458 }
459
460 return true;
461 }
462
463 static void set_return_assign_state(struct db_callback_info *db_info)
464 {
465 struct expression *expr = db_info->expr->left;
466 struct smatch_state *state;
467
468 if (!db_info->ret_state)
469 return;
470
471 state = alloc_estate_rl(cast_rl(get_type(expr), clone_rl(estate_rl(db_info->ret_state))));
472 if (!fake_a_param_assignment(db_info->expr, db_info->ret_str, state))
473 set_extra_expr_mod(expr, state);
474
475 db_info->ret_state = NULL;
476 db_info->ret_str = NULL;
477 }
478
479 static void set_other_side_state(struct db_callback_info *db_info)
480 {
481 struct expression *expr = db_info->var_expr;
482 struct smatch_state *state;
483
484 if (!db_info->ret_state)
485 return;
486
487 state = alloc_estate_rl(cast_rl(get_type(expr), clone_rl(estate_rl(db_info->ret_state))));
488 set_extra_expr_nomod(expr, state);
489 db_info->ret_state = NULL;
490 db_info->ret_str = NULL;
491 }
492
493 static void handle_ret_equals_param(char *ret_string, struct range_list *rl, struct expression *call)
494 {
495 char *str;
496 long long param;
497 struct expression *arg;
498 struct range_list *orig;
499
500 str = strstr(ret_string, "==$");
501 if (!str)
502 return;
503 str += 3;
504 param = strtoll(str, NULL, 10);
505 arg = get_argument_from_call_expr(call->args, param);
506 if (!arg)
507 return;
508 get_absolute_rl(arg, &orig);
509 rl = rl_intersection(orig, rl);
510 if (!rl)
511 return;
512 set_extra_expr_nomod(arg, alloc_estate_rl(rl));
513 }
514
515 static int impossible_limit(struct expression *expr, int param, char *key, char *value)
516 {
517 struct expression *arg;
518 struct smatch_state *state;
519 struct range_list *passed;
520 struct range_list *limit;
521 struct symbol *compare_type;
522
523 while (expr->type == EXPR_ASSIGNMENT)
524 expr = strip_expr(expr->right);
525 if (expr->type != EXPR_CALL)
526 return 0;
527
528 arg = get_argument_from_call_expr(expr->args, param);
529 if (!arg)
530 return 0;
531
532 if (strcmp(key, "$") == 0) {
533 if (!get_implied_rl(arg, &passed))
534 return 0;
535
536 compare_type = get_arg_type(expr->fn, param);
537 } else {
538 char *name;
539 struct symbol *sym;
540
541 name = get_variable_from_key(arg, key, &sym);
542 if (!name || !sym)
543 return 0;
544
545 state = get_state(SMATCH_EXTRA, name, sym);
546 if (!state) {
547 free_string(name);
548 return 0;
549 }
550 passed = estate_rl(state);
551 if (!passed || is_whole_rl(passed)) {
552 free_string(name);
553 return 0;
554 }
555
556 compare_type = get_member_type_from_key(arg, key);
557 }
558
559 passed = cast_rl(compare_type, passed);
560 call_results_to_rl(expr, compare_type, value, &limit);
561 if (!limit || is_whole_rl(limit))
562 return 0;
563 if (possibly_true_rl(passed, SPECIAL_EQUAL, limit))
564 return 0;
565 if (option_debug || local_debug)
566 sm_msg("impossible: %d '%s' limit '%s' == '%s'", param, key, show_rl(passed), value);
567 return 1;
568 }
569
570 static int is_impossible_data(int type, struct expression *expr, int param, char *key, char *value)
571 {
572 if (type == PARAM_LIMIT && impossible_limit(expr, param, key, value))
573 return 1;
574 if (type == COMPARE_LIMIT && param_compare_limit_is_impossible(expr, param, key, value)) {
575 if (local_debug)
576 sm_msg("param_compare_limit_is_impossible: %d %s %s", param, key, value);
577 return 1;
578 }
579 return 0;
580 }
581
582 static int func_type_mismatch(struct expression *expr, const char *value)
583 {
584 struct symbol *type;
585
586 /* This makes faking returns easier */
587 if (!value || value[0] == '\0')
588 return 0;
589
590 while (expr->type == EXPR_ASSIGNMENT)
591 expr = strip_expr(expr->right);
592
593 /*
594 * Short cut: We only care about function pointers that are struct
595 * members.
596 *
597 */
598 if (expr->fn->type == EXPR_SYMBOL)
599 return 0;
600
601 type = get_type(expr->fn);
602 if (!type)
603 return 0;
604 if (type->type == SYM_PTR)
605 type = get_real_base_type(type);
606
607 if (strcmp(type_to_str(type), value) == 0)
608 return 0;
609
610 return 1;
611 }
612
613 static int db_compare_callback(void *_info, int argc, char **argv, char **azColName)
614 {
615 struct db_callback_info *db_info = _info;
616 struct range_list *var_rl = db_info->rl;
617 struct range_list *ret_range;
618 int type, param;
619 char *ret_str, *key, *value;
620 struct return_implies_callback *tmp;
621 struct stree *stree;
622 int return_id;
623 int comparison;
624
625 if (argc != 6)
626 return 0;
627
628 return_id = atoi(argv[0]);
629 ret_str = argv[1];
630 type = atoi(argv[2]);
631 param = atoi(argv[3]);
632 key = argv[4];
633 value = argv[5];
634
635 db_info->has_states = 1;
636 if (db_info->prev_return_id != -1 && type == INTERNAL) {
637 set_other_side_state(db_info);
638 stree = __pop_fake_cur_stree();
639
640 if (!db_info->cull)
641 merge_fake_stree(&db_info->stree, stree);
642 free_stree(&stree);
643 __push_fake_cur_stree();
644 db_info->cull = 0;
645 }
646 db_info->prev_return_id = return_id;
647
648 if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
649 db_info->cull = 1;
650 if (db_info->cull)
651 return 0;
652 if (type == CULL_PATH) {
653 db_info->cull = 1;
654 return 0;
655 }
656
657 if (is_impossible_data(type, db_info->expr, param, key, value)) {
658 db_info->cull = 1;
659 return 0;
660 }
661
662 call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), ret_str, &ret_range);
663 ret_range = cast_rl(get_type(db_info->expr), ret_range);
664 if (!ret_range)
665 ret_range = alloc_whole_rl(get_type(db_info->expr));
666
667 comparison = db_info->comparison;
668 if (db_info->left)
669 comparison = flip_comparison(comparison);
670
671 if (db_info->true_side) {
672 if (!possibly_true_rl(var_rl, comparison, ret_range))
673 return 0;
674 if (type == PARAM_LIMIT)
675 param_limit_implications(db_info->expr, param, key, value);
676 filter_by_comparison(&var_rl, comparison, ret_range);
677 filter_by_comparison(&ret_range, flip_comparison(comparison), var_rl);
678 } else {
679 if (!possibly_false_rl(var_rl, comparison, ret_range))
680 return 0;
681 if (type == PARAM_LIMIT)
682 param_limit_implications(db_info->expr, param, key, value);
683 filter_by_comparison(&var_rl, negate_comparison(comparison), ret_range);
684 filter_by_comparison(&ret_range, flip_comparison(negate_comparison(comparison)), var_rl);
685 }
686
687 handle_ret_equals_param(ret_str, ret_range, db_info->expr);
688
689 if (type == INTERNAL) {
690 set_state(-1, "unnull_path", NULL, &true_state);
691 __add_return_comparison(strip_expr(db_info->expr), ret_str);
692 __add_return_to_param_mapping(db_info->expr, ret_str);
693 store_return_state(db_info, ret_str, alloc_estate_rl(clone_rl(var_rl)));
694 }
695
696 FOR_EACH_PTR(db_info->callbacks, tmp) {
697 if (tmp->type == type)
698 tmp->callback(db_info->expr, param, key, value);
699 } END_FOR_EACH_PTR(tmp);
700
701 return 0;
702 }
703
704 static void compare_db_return_states_callbacks(struct expression *left, int comparison, struct expression *right, struct stree *implied_true, struct stree *implied_false)
705 {
706 struct stree *orig_states;
707 struct stree *stree;
708 struct stree *true_states;
709 struct stree *false_states;
710 struct sm_state *sm;
711 struct db_callback_info db_info = {};
712 struct expression *var_expr;
713 struct expression *call_expr;
714 struct range_list *rl;
715 int call_on_left;
716
717 orig_states = clone_stree(__get_cur_stree());
718
719 /* legacy cruft. need to fix call_implies_callbacks(). */
720 call_on_left = 1;
721 call_expr = left;
722 var_expr = right;
723 if (left->type != EXPR_CALL) {
724 call_on_left = 0;
725 call_expr = right;
726 var_expr = left;
727 }
728
729 get_absolute_rl(var_expr, &rl);
730
731 db_info.comparison = comparison;
732 db_info.expr = call_expr;
733 db_info.rl = rl;
734 db_info.left = call_on_left;
735 db_info.callbacks = db_return_states_list;
736 db_info.var_expr = var_expr;
737
738 call_return_states_before_hooks();
739
740 db_info.true_side = 1;
741 db_info.stree = NULL;
742 db_info.prev_return_id = -1;
743 __push_fake_cur_stree();
744 sql_select_return_states("return_id, return, type, parameter, key, value",
745 call_expr, db_compare_callback, &db_info);
746 set_other_side_state(&db_info);
747 stree = __pop_fake_cur_stree();
748 if (!db_info.cull)
749 merge_fake_stree(&db_info.stree, stree);
750 free_stree(&stree);
751 true_states = db_info.stree;
752 if (!true_states && db_info.has_states) {
753 __push_fake_cur_stree();
754 set_path_impossible();
755 true_states = __pop_fake_cur_stree();
756 }
757
758 nullify_path();
759 __unnullify_path();
760 FOR_EACH_SM(orig_states, sm) {
761 __set_sm_cur_stree(sm);
762 } END_FOR_EACH_SM(sm);
763
764 db_info.true_side = 0;
765 db_info.stree = NULL;
766 db_info.prev_return_id = -1;
767 db_info.cull = 0;
768 __push_fake_cur_stree();
769 sql_select_return_states("return_id, return, type, parameter, key, value", call_expr,
770 db_compare_callback, &db_info);
771 set_other_side_state(&db_info);
772 stree = __pop_fake_cur_stree();
773 if (!db_info.cull)
774 merge_fake_stree(&db_info.stree, stree);
775 free_stree(&stree);
776 false_states = db_info.stree;
777 if (!false_states && db_info.has_states) {
778 __push_fake_cur_stree();
779 set_path_impossible();
780 false_states = __pop_fake_cur_stree();
781 }
782
783 nullify_path();
784 __unnullify_path();
785 FOR_EACH_SM(orig_states, sm) {
786 __set_sm_cur_stree(sm);
787 } END_FOR_EACH_SM(sm);
788
789 free_stree(&orig_states);
790
791 FOR_EACH_SM(true_states, sm) {
792 __set_true_false_sm(sm, NULL);
793 } END_FOR_EACH_SM(sm);
794 FOR_EACH_SM(false_states, sm) {
795 __set_true_false_sm(NULL, sm);
796 } END_FOR_EACH_SM(sm);
797
798 free_stree(&true_states);
799 free_stree(&false_states);
800
801 call_return_states_after_hooks(call_expr);
802
803 FOR_EACH_SM(implied_true, sm) {
804 __set_true_false_sm(sm, NULL);
805 } END_FOR_EACH_SM(sm);
806 FOR_EACH_SM(implied_false, sm) {
807 __set_true_false_sm(NULL, sm);
808 } END_FOR_EACH_SM(sm);
809 }
810
811 void function_comparison(struct expression *left, int comparison, struct expression *right)
812 {
813 struct expression *var_expr;
814 struct expression *call_expr;
815 struct stree *implied_true = NULL;
816 struct stree *implied_false = NULL;
817 struct range_list *rl;
818 sval_t sval;
819 int call_on_left;
820
821 if (unreachable())
822 return;
823
824 /* legacy cruft. need to fix call_implies_callbacks(). */
825 call_on_left = 1;
826 call_expr = left;
827 var_expr = right;
828 if (left->type != EXPR_CALL) {
829 call_on_left = 0;
830 call_expr = right;
831 var_expr = left;
832 }
833
834 get_absolute_rl(var_expr, &rl);
835
836 if (rl_to_sval(rl, &sval))
837 call_implies_callbacks(comparison, call_expr, sval, call_on_left, &implied_true, &implied_false);
838
839 compare_db_return_states_callbacks(left, comparison, right, implied_true, implied_false);
840 free_stree(&implied_true);
841 free_stree(&implied_false);
842 }
843
844 static void call_ranged_return_hooks(struct db_callback_info *db_info)
845 {
846 struct call_back_list *call_backs;
847 struct expression *expr;
848 struct fcall_back *tmp;
849 char *fn;
850
851 expr = strip_expr(db_info->expr);
852 while (expr->type == EXPR_ASSIGNMENT)
853 expr = strip_expr(expr->right);
854 if (expr->type != EXPR_CALL ||
855 expr->fn->type != EXPR_SYMBOL)
856 return;
857
858 fn = expr->fn->symbol_name->name;
859
860 call_backs = search_callback(func_hash, fn);
861 FOR_EACH_PTR(call_backs, tmp) {
862 struct range_list *range_rl;
863
864 if (tmp->type != RANGED_CALL)
865 continue;
866 range_rl = alloc_rl(tmp->range->min, tmp->range->max);
867 range_rl = cast_rl(estate_type(db_info->ret_state), range_rl);
868 if (possibly_true_rl(range_rl, SPECIAL_EQUAL, estate_rl(db_info->ret_state)))
869 (tmp->u.ranged)(fn, expr, db_info->expr, tmp->info);
870 } END_FOR_EACH_PTR(tmp);
871 }
872
873 static int db_assign_return_states_callback(void *_info, int argc, char **argv, char **azColName)
874 {
875 struct db_callback_info *db_info = _info;
876 struct range_list *ret_range;
877 int type, param;
878 char *ret_str, *key, *value;
879 struct return_implies_callback *tmp;
880 struct stree *stree;
881 int return_id;
882
883 if (argc != 6)
884 return 0;
885
886 return_id = atoi(argv[0]);
887 ret_str = argv[1];
888 type = atoi(argv[2]);
889 param = atoi(argv[3]);
890 key = argv[4];
891 value = argv[5];
892
893 if (db_info->prev_return_id != -1 && type == INTERNAL) {
894 call_ranged_return_hooks(db_info);
895 set_return_assign_state(db_info);
896 stree = __pop_fake_cur_stree();
897 if (!db_info->cull)
898 merge_fake_stree(&db_info->stree, stree);
899 free_stree(&stree);
900 __push_fake_cur_stree();
901 db_info->cull = 0;
902 }
903 db_info->prev_return_id = return_id;
904
905 if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
906 db_info->cull = 1;
907 if (db_info->cull)
908 return 0;
909 if (type == CULL_PATH) {
910 db_info->cull = 1;
911 return 0;
912 }
913 if (is_impossible_data(type, db_info->expr, param, key, value)) {
914 db_info->cull = 1;
915 return 0;
916 }
917
918 if (type == PARAM_LIMIT)
919 param_limit_implications(db_info->expr, param, key, value);
920
921 db_info->handled = 1;
922 call_results_to_rl(db_info->expr->right, get_type(strip_expr(db_info->expr->right)), ret_str, &ret_range);
923 if (!ret_range)
924 ret_range = alloc_whole_rl(get_type(strip_expr(db_info->expr->right)));
925 ret_range = cast_rl(get_type(db_info->expr->right), ret_range);
926
927 if (type == INTERNAL) {
928 set_state(-1, "unnull_path", NULL, &true_state);
929 __add_return_comparison(strip_expr(db_info->expr->right), ret_str);
930 __add_comparison_info(db_info->expr->left, strip_expr(db_info->expr->right), ret_str);
931 __add_return_to_param_mapping(db_info->expr, ret_str);
932 store_return_state(db_info, ret_str, alloc_estate_rl(ret_range));
933 }
934
935 FOR_EACH_PTR(db_return_states_list, tmp) {
936 if (tmp->type == type)
937 tmp->callback(db_info->expr, param, key, value);
938 } END_FOR_EACH_PTR(tmp);
939
940 return 0;
941 }
942
943 static int db_return_states_assign(struct expression *expr)
944 {
945 struct expression *right;
946 struct sm_state *sm;
947 struct stree *stree;
948 struct db_callback_info db_info = {};
949
950 right = strip_expr(expr->right);
951
952 db_info.prev_return_id = -1;
953 db_info.expr = expr;
954 db_info.stree = NULL;
955 db_info.handled = 0;
956
957 call_return_states_before_hooks();
958
959 __push_fake_cur_stree();
960 sql_select_return_states("return_id, return, type, parameter, key, value",
961 right, db_assign_return_states_callback, &db_info);
962 if (option_debug) {
963 sm_msg("%s return_id %d return_ranges %s",
964 db_info.cull ? "culled" : "merging",
965 db_info.prev_return_id,
966 db_info.ret_state ? db_info.ret_state->name : "'<empty>'");
967 }
968 if (db_info.handled)
969 call_ranged_return_hooks(&db_info);
970 set_return_assign_state(&db_info);
971 stree = __pop_fake_cur_stree();
972 if (!db_info.cull)
973 merge_fake_stree(&db_info.stree, stree);
974 free_stree(&stree);
975
976 if (!db_info.stree && db_info.cull) { /* this means we culled everything */
977 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
978 set_path_impossible();
979 }
980 FOR_EACH_SM(db_info.stree, sm) {
981 __set_sm(sm);
982 } END_FOR_EACH_SM(sm);
983
984 free_stree(&db_info.stree);
985 call_return_states_after_hooks(right);
986
987 return db_info.handled;
988 }
989
990 static int handle_implied_return(struct expression *expr)
991 {
992 struct range_list *rl;
993
994 if (!get_implied_return(expr->right, &rl))
995 return 0;
996 rl = cast_rl(get_type(expr->left), rl);
997 set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
998 return 1;
999 }
1000
1001 static void match_assign_call(struct expression *expr)
1002 {
1003 struct call_back_list *call_backs;
1004 const char *fn;
1005 struct expression *right;
1006 int handled = 0;
1007 struct range_list *rl;
1008
1009 if (expr->op != '=')
1010 return;
1011
1012 right = strip_expr(expr->right);
1013 if (right->fn->type != EXPR_SYMBOL || !right->fn->symbol) {
1014 handled |= db_return_states_assign(expr);
1015 if (!handled)
1016 goto assigned_unknown;
1017 return;
1018 }
1019 if (is_fake_call(right)) {
1020 set_extra_expr_mod(expr->left, alloc_estate_whole(get_type(expr->left)));
1021 return;
1022 }
1023
1024 fn = right->fn->symbol->ident->name;
1025 call_backs = search_callback(func_hash, (char *)fn);
1026
1027 /*
1028 * The ordering here is sort of important.
1029 * One example, of how this matters is that when we do:
1030 *
1031 * len = strlen(str);
1032 *
1033 * That is handled by smatch_common_functions.c and smatch_strlen.c.
1034 * They use implied_return and function_assign_hook respectively.
1035 * We want to get the implied return first before we do the function
1036 * assignment hook otherwise we end up writing the wrong thing for len
1037 * in smatch_extra.c because we assume that it already holds the
1038 * strlen() when we haven't set it yet.
1039 */
1040
1041 if (db_return_states_assign(expr) == 1)
1042 handled = 1;
1043 else
1044 handled = assign_ranged_funcs(fn, expr, call_backs);
1045 handled |= handle_implied_return(expr);
1046
1047
1048 call_call_backs(call_backs, ASSIGN_CALL, fn, expr);
1049
1050 if (handled)
1051 return;
1052
1053 assigned_unknown:
1054 get_absolute_rl(expr->right, &rl);
1055 rl = cast_rl(get_type(expr->left), rl);
1056 set_extra_expr_mod(expr->left, alloc_estate_rl(rl));
1057 }
1058
1059 static int db_return_states_callback(void *_info, int argc, char **argv, char **azColName)
1060 {
1061 struct db_callback_info *db_info = _info;
1062 struct range_list *ret_range;
1063 int type, param;
1064 char *ret_str, *key, *value;
1065 struct return_implies_callback *tmp;
1066 struct stree *stree;
1067 int return_id;
1068 char buf[64];
1069
1070 if (argc != 6)
1071 return 0;
1072
1073 return_id = atoi(argv[0]);
1074 ret_str = argv[1];
1075 type = atoi(argv[2]);
1076 param = atoi(argv[3]);
1077 key = argv[4];
1078 value = argv[5];
1079
1080 if (db_info->prev_return_id != -1 && type == INTERNAL) {
1081 stree = __pop_fake_cur_stree();
1082 if (!db_info->cull)
1083 merge_fake_stree(&db_info->stree, stree);
1084 free_stree(&stree);
1085 __push_fake_cur_stree();
1086 __unnullify_path();
1087 db_info->cull = 0;
1088 }
1089 db_info->prev_return_id = return_id;
1090
1091 if (type == INTERNAL && func_type_mismatch(db_info->expr, value))
1092 db_info->cull = 1;
1093 if (db_info->cull)
1094 return 0;
1095 if (type == CULL_PATH) {
1096 db_info->cull = 1;
1097 return 0;
1098 }
1099 if (is_impossible_data(type, db_info->expr, param, key, value)) {
1100 db_info->cull = 1;
1101 return 0;
1102 }
1103
1104 if (type == PARAM_LIMIT)
1105 param_limit_implications(db_info->expr, param, key, value);
1106
1107 call_results_to_rl(db_info->expr, get_type(strip_expr(db_info->expr)), ret_str, &ret_range);
1108 ret_range = cast_rl(get_type(db_info->expr), ret_range);
1109
1110 if (type == INTERNAL) {
1111 set_state(-1, "unnull_path", NULL, &true_state);
1112 __add_return_comparison(strip_expr(db_info->expr), ret_str);
1113 __add_return_to_param_mapping(db_info->expr, ret_str);
1114 }
1115
1116 FOR_EACH_PTR(db_return_states_list, tmp) {
1117 if (tmp->type == type)
1118 tmp->callback(db_info->expr, param, key, value);
1119 } END_FOR_EACH_PTR(tmp);
1120
1121 /*
1122 * We want to store the return values so that we can split the strees
1123 * in smatch_db.c. This uses set_state() directly because it's not a
1124 * real smatch_extra state.
1125 */
1126 snprintf(buf, sizeof(buf), "return %p", db_info->expr);
1127 set_state(SMATCH_EXTRA, buf, NULL, alloc_estate_rl(ret_range));
1128
1129 return 0;
1130 }
1131
1132 static void db_return_states(struct expression *expr)
1133 {
1134 struct sm_state *sm;
1135 struct stree *stree;
1136 struct db_callback_info db_info = {};
1137
1138 if (!__get_cur_stree()) /* no return functions */
1139 return;
1140
1141 db_info.prev_return_id = -1;
1142 db_info.expr = expr;
1143 db_info.stree = NULL;
1144
1145 call_return_states_before_hooks();
1146
1147 __push_fake_cur_stree();
1148 __unnullify_path();
1149 sql_select_return_states("return_id, return, type, parameter, key, value",
1150 expr, db_return_states_callback, &db_info);
1151 stree = __pop_fake_cur_stree();
1152 if (!db_info.cull)
1153 merge_fake_stree(&db_info.stree, stree);
1154 free_stree(&stree);
1155
1156 FOR_EACH_SM(db_info.stree, sm) {
1157 __set_sm(sm);
1158 } END_FOR_EACH_SM(sm);
1159
1160 free_stree(&db_info.stree);
1161 call_return_states_after_hooks(expr);
1162 }
1163
1164 static int is_condition_call(struct expression *expr)
1165 {
1166 struct expression *tmp;
1167
1168 FOR_EACH_PTR_REVERSE(big_condition_stack, tmp) {
1169 if (expr == tmp || expr_get_parent_expr(expr) == tmp)
1170 return 1;
1171 if (tmp->pos.line < expr->pos.line)
1172 return 0;
1173 } END_FOR_EACH_PTR_REVERSE(tmp);
1174
1175 return 0;
1176 }
1177
1178 static void db_return_states_call(struct expression *expr)
1179 {
1180 if (unreachable())
1181 return;
1182
1183 if (is_assigned_call(expr))
1184 return;
1185 if (is_condition_call(expr))
1186 return;
1187 db_return_states(expr);
1188 }
1189
1190 static void match_function_call(struct expression *expr)
1191 {
1192 struct call_back_list *call_backs;
1193 struct expression *fn;
1194
1195 fn = strip_expr(expr->fn);
1196 if (fn->type == EXPR_SYMBOL && fn->symbol) {
1197 call_backs = search_callback(func_hash, (char *)fn->symbol->ident->name);
1198 if (call_backs)
1199 call_call_backs(call_backs, REGULAR_CALL,
1200 fn->symbol->ident->name, expr);
1201 }
1202 db_return_states_call(expr);
1203 }
1204
1205 static void match_macro_assign(struct expression *expr)
1206 {
1207 struct call_back_list *call_backs;
1208 const char *macro;
1209 struct expression *right;
1210
1211 right = strip_expr(expr->right);
1212 macro = get_macro_name(right->pos);
1213 call_backs = search_callback(func_hash, (char *)macro);
1214 if (!call_backs)
1215 return;
1216 call_call_backs(call_backs, MACRO_ASSIGN, macro, expr);
1217 call_call_backs(call_backs, MACRO_ASSIGN_EXTRA, macro, expr);
1218 }
1219
1220 int get_implied_return(struct expression *expr, struct range_list **rl)
1221 {
1222 struct call_back_list *call_backs;
1223 struct fcall_back *tmp;
1224 int handled = 0;
1225 char *fn;
1226
1227 *rl = NULL;
1228
1229 expr = strip_expr(expr);
1230 fn = expr_to_var(expr->fn);
1231 if (!fn)
1232 goto out;
1233
1234 call_backs = search_callback(func_hash, fn);
1235
1236 FOR_EACH_PTR(call_backs, tmp) {
1237 if (tmp->type == IMPLIED_RETURN) {
1238 (tmp->u.implied_return)(expr, tmp->info, rl);
1239 handled = 1;
1240 }
1241 } END_FOR_EACH_PTR(tmp);
1242
1243 out:
1244 free_string(fn);
1245 return handled;
1246 }
1247
1248 void create_function_hook_hash(void)
1249 {
1250 func_hash = create_function_hashtable(5000);
1251 }
1252
1253 void register_function_hooks(int id)
1254 {
1255 add_hook(&match_function_call, CALL_HOOK_AFTER_INLINE);
1256 add_hook(&match_assign_call, CALL_ASSIGNMENT_HOOK);
1257 add_hook(&match_macro_assign, MACRO_ASSIGNMENT_HOOK);
1258 }