1 /*
2 * Copyright (C) 2012 Oracle.
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 almost the same as smatch_param_filter.c. The difference is that
20 * this only deals with values passed on the stack and param filter only deals
21 * with values changed so that the caller sees the new value. It other words
22 * the key for these should always be "$" and the key for param_filter should
23 * never be "$". Also smatch_param_set() should never use "$" as the key.
24 * Param set should work together with param_filter to determine the value that
25 * the caller sees at the end.
26 *
27 * This is for functions like this:
28 *
29 * int foo(int a)
30 * {
31 * if (a >= 0 && a < 10) {
32 * a = 42;
33 * return 1;
34 * }
35 * return 0;
36 * }
37 *
38 * If we pass in 5, it returns 1.
39 *
40 * It's a bit complicated because we can't just consider the final value, we
41 * have to always consider the passed in value.
42 *
43 */
44
45 #include "scope.h"
46 #include "smatch.h"
47 #include "smatch_extra.h"
48 #include "smatch_slist.h"
49
50 static int my_id;
51
52 static struct stree *start_states;
53 static struct stree_stack *saved_stack;
54
save_start_states(struct statement * stmt)55 static void save_start_states(struct statement *stmt)
56 {
57 start_states = get_all_states_stree(SMATCH_EXTRA);
58 }
59
free_start_states(void)60 static void free_start_states(void)
61 {
62 free_stree(&start_states);
63 }
64
unmatched_state(struct sm_state * sm)65 static struct smatch_state *unmatched_state(struct sm_state *sm)
66 {
67 struct smatch_state *state;
68
69 state = __get_state(SMATCH_EXTRA, sm->name, sm->sym);
70 if (state)
71 return state;
72 return alloc_estate_whole(estate_type(sm->state));
73 }
74
get_orig_estate(const char * name,struct symbol * sym)75 struct smatch_state *get_orig_estate(const char *name, struct symbol *sym)
76 {
77 struct smatch_state *state;
78
79 state = get_state(my_id, name, sym);
80 if (state)
81 return state;
82
83 state = get_state(SMATCH_EXTRA, name, sym);
84 if (state)
85 return state;
86 return alloc_estate_rl(alloc_whole_rl(get_real_base_type(sym)));
87 }
88
get_orig_estate_type(const char * name,struct symbol * sym,struct symbol * type)89 struct smatch_state *get_orig_estate_type(const char *name, struct symbol *sym, struct symbol *type)
90 {
91 struct smatch_state *state;
92
93 state = get_state(my_id, name, sym);
94 if (state)
95 return state;
96
97 state = get_state(SMATCH_EXTRA, name, sym);
98 if (state)
99 return state;
100 return alloc_estate_rl(alloc_whole_rl(type));
101 }
102
generify_mtag_range(struct smatch_state * state)103 static struct range_list *generify_mtag_range(struct smatch_state *state)
104 {
105 struct range_list *rl;
106 struct data_range *drange;
107
108 if (!estate_type(state) || estate_type(state)->type != SYM_PTR)
109 return estate_rl(state);
110
111 /*
112 * The problem is that we get too specific on our param limits when we
113 * know exactly what pointers are passed to a function. It gets to the
114 * point where we say "pointer x will succeed, but everything else will
115 * fail." And then we introduce a new caller which passes a different
116 * pointer and it's like, "Sorry bro, that's not possible."
117 *
118 */
119 rl = estate_rl(state);
120 FOR_EACH_PTR(rl, drange) {
121 if (drange->min.value != drange->max.value)
122 continue;
123 if (drange->min.value == 0)
124 continue;
125 if (is_err_ptr(drange->min))
126 continue;
127 return rl_union(valid_ptr_rl, rl);
128 } END_FOR_EACH_PTR(drange);
129
130 return estate_rl(state);
131 }
132
print_return_value_param(int return_id,char * return_ranges,struct expression * expr)133 static void print_return_value_param(int return_id, char *return_ranges, struct expression *expr)
134 {
135 struct smatch_state *state, *old;
136 struct sm_state *tmp;
137 struct range_list *rl;
138 const char *param_name;
139 int param;
140
141 FOR_EACH_MY_SM(SMATCH_EXTRA, __get_cur_stree(), tmp) {
142 param = get_param_num_from_sym(tmp->sym);
143 if (param < 0)
144 continue;
145
146 param_name = get_param_name(tmp);
147 if (!param_name)
148 continue;
149
150 state = __get_state(my_id, tmp->name, tmp->sym);
151 if (!state)
152 state = tmp->state;
153
154 if (estate_is_whole(state) || estate_is_empty(state))
155 continue;
156 old = get_state_stree(start_states, SMATCH_EXTRA, tmp->name, tmp->sym);
157 if (old && rl_equiv(estate_rl(old), estate_rl(state)))
158 continue;
159
160 if (is_ignored_kernel_data(param_name))
161 continue;
162
163 rl = generify_mtag_range(state);
164 sql_insert_return_states(return_id, return_ranges, PARAM_LIMIT,
165 param, param_name, show_rl(rl));
166 } END_FOR_EACH_SM(tmp);
167 }
168
extra_mod_hook(const char * name,struct symbol * sym,struct expression * expr,struct smatch_state * state)169 static void extra_mod_hook(const char *name, struct symbol *sym, struct expression *expr, struct smatch_state *state)
170 {
171 struct smatch_state *orig_vals;
172 int param;
173
174 param = get_param_num_from_sym(sym);
175 if (param < 0)
176 return;
177
178 orig_vals = get_orig_estate_type(name, sym, estate_type(state));
179 set_state(my_id, name, sym, orig_vals);
180 }
181
match_save_states(struct expression * expr)182 static void match_save_states(struct expression *expr)
183 {
184 push_stree(&saved_stack, start_states);
185 start_states = NULL;
186 }
187
match_restore_states(struct expression * expr)188 static void match_restore_states(struct expression *expr)
189 {
190 free_stree(&start_states);
191 start_states = pop_stree(&saved_stack);
192 }
193
register_param_limit(int id)194 void register_param_limit(int id)
195 {
196 my_id = id;
197
198 set_dynamic_states(my_id);
199 add_hook(&save_start_states, AFTER_DEF_HOOK);
200 add_hook(&free_start_states, AFTER_FUNC_HOOK);
201
202 add_extra_mod_hook(&extra_mod_hook);
203 add_unmatched_state_hook(my_id, &unmatched_state);
204 add_merge_hook(my_id, &merge_estates);
205
206 add_hook(&match_save_states, INLINE_FN_START);
207 add_hook(&match_restore_states, INLINE_FN_END);
208
209 add_split_return_callback(&print_return_value_param);
210 }
211
212