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 *rl = cast_rl(get_type(arg), *rl);
38 }
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 *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 call_results_to_rl(call_expr, &ptr_ctype, "0,(-4095)-(-1)", &rl);
114 rl = rl_intersection(estate_rl(pre_state), rl);
115 rl = cast_rl(get_type(arg), rl);
116 end_state = alloc_estate_rl(rl);
117 set_extra_expr_nomod(arg, end_state);
118 }
119
120 static void match_not_err(const char *fn, struct expression *call_expr,
121 struct expression *assign_expr, void *unused)
122 {
123 struct expression *arg;
124 struct smatch_state *pre_state;
125 struct range_list *rl;
126
127 arg = get_argument_from_call_expr(call_expr->args, 0);
128 pre_state = get_state_expr(SMATCH_EXTRA, arg);
129 if (estate_rl(pre_state)) {
130 rl = estate_rl(pre_state);
131 rl = remove_range(rl, err_ptr_min, err_ptr_max);
132 } else {
133 rl = alloc_rl(valid_ptr_min_sval, valid_ptr_max_sval);
134 }
135 rl = cast_rl(get_type(arg), rl);
136 set_extra_expr_nomod(arg, alloc_estate_rl(rl));
137 }
138
139 static void match_err(const char *fn, struct expression *call_expr,
140 struct expression *assign_expr, void *unused)
141 {
142 struct expression *arg;
143 struct smatch_state *pre_state;
144 struct range_list *rl;
145
146 arg = get_argument_from_call_expr(call_expr->args, 0);
147 pre_state = get_state_expr(SMATCH_EXTRA, arg);
148 rl = estate_rl(pre_state);
149 if (!rl)
150 rl = alloc_rl(err_ptr_min, err_ptr_max);
151 rl = rl_intersection(rl, alloc_rl(err_ptr_min, err_ptr_max));
152 rl = cast_rl(get_type(arg), rl);
153 set_extra_expr_nomod(arg, alloc_estate_rl(rl));
154 }
155
156 static void match_container_of_macro(const char *fn, struct expression *expr, void *unused)
157 {
158 set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
159 }
160
161 static void match_container_of(struct expression *expr)
162 {
163 struct expression *right = expr->right;
164 char *macro;
165
166 /*
167 * The problem here is that sometimes the container_of() macro is itself
168 * inside a macro and get_macro() only returns the name of the outside
169 * macro.
170 */
171
172 /*
173 * This actually an expression statement assignment but smatch_flow
174 * pre-mangles it for us so we only get the last chunk:
175 * sk = (typeof(sk))((char *)__mptr - offsetof(...))
176 */
177
178 macro = get_macro_name(right->pos);
179 if (!macro)
180 return;
181 if (right->type != EXPR_CAST)
182 return;
183 right = strip_expr(right);
184 if (right->type != EXPR_BINOP || right->op != '-' ||
185 right->left->type != EXPR_CAST)
186 return;
187 right = strip_expr(right->left);
188 if (right->type != EXPR_SYMBOL)
189 return;
190 if (!right->symbol->ident ||
191 strcmp(right->symbol->ident->name, "__mptr") != 0)
192 return;
193 set_extra_expr_mod(expr->left, alloc_estate_range(valid_ptr_min_sval, valid_ptr_max_sval));
194 }
195
196 static int match_next_bit(struct expression *call, void *unused, struct range_list **rl)
197 {
198 struct expression *start_arg;
199 struct expression *size_arg;
200 struct symbol *type;
201 sval_t min, max, tmp;
202
203 size_arg = get_argument_from_call_expr(call->args, 1);
204 /* btw. there isn't a start_arg for find_first_bit() */
205 start_arg = get_argument_from_call_expr(call->args, 2);
206
207 type = get_type(call);
208 min = sval_type_val(type, 0);
209 max = sval_type_val(type, sizeof(long long) * 8);
210
211 if (get_implied_max(size_arg, &tmp) && tmp.uvalue < max.value)
212 max = tmp;
213 if (start_arg && get_implied_min(start_arg, &tmp) && !sval_is_negative(tmp))
214 min = tmp;
215 if (sval_cmp(min, max) > 0)
216 max = min;
217 min = sval_cast(type, min);
218 max = sval_cast(type, max);
219 *rl = alloc_rl(min, max);
220 return 1;
221 }
222
223 static int match_fls(struct expression *call, void *unused, struct range_list **rl)
224 {
225 struct expression *arg;
226 struct range_list *arg_rl;
227 sval_t zero = {};
228 sval_t start, end, sval;
229
230 start.type = &int_ctype;
231 start.value = 0;
232 end.type = &int_ctype;
233 end.value = 32;
234
235 arg = get_argument_from_call_expr(call->args, 0);
236 if (!get_implied_rl(arg, &arg_rl))
237 return 0;
238 if (rl_to_sval(arg_rl, &sval)) {
239 int i;
240
241 for (i = 63; i >= 0; i--) {
242 if (sval.uvalue & 1ULL << i)
243 break;
244 }
245 sval.value = i + 1;
246 *rl = alloc_rl(sval, sval);
247 return 1;
248 }
249 zero.type = rl_type(arg_rl);
250 if (!rl_has_sval(arg_rl, zero))
251 start.value = 1;
252 *rl = alloc_rl(start, end);
253 return 1;
254 }
255
256
257
258 static void find_module_init_exit(struct symbol_list *sym_list)
259 {
260 struct symbol *sym;
261 struct symbol *fn;
262 struct statement *stmt;
263 char *name;
264 int init;
265 int count;
266
267 /*
268 * This is more complicated because Sparse ignores the "alias"
269 * attribute. I search backwards because module_init() is normally at
270 * the end of the file.
271 */
272 count = 0;
273 FOR_EACH_PTR_REVERSE(sym_list, sym) {
274 if (sym->type != SYM_NODE)
275 continue;
276 if (!(sym->ctype.modifiers & MOD_STATIC))
277 continue;
278 fn = get_base_type(sym);
279 if (!fn)
280 continue;
281 if (fn->type != SYM_FN)
282 continue;
283 if (!sym->ident)
284 continue;
285 if (!fn->inline_stmt)
286 continue;
287 if (strcmp(sym->ident->name, "__inittest") == 0)
288 init = 1;
289 else if (strcmp(sym->ident->name, "__exittest") == 0)
290 init = 0;
291 else
292 continue;
293
294 count++;
295
296 stmt = first_ptr_list((struct ptr_list *)fn->inline_stmt->stmts);
297 if (!stmt || stmt->type != STMT_RETURN)
298 continue;
299 name = expr_to_var(stmt->ret_value);
300 if (!name)
301 continue;
302 if (init)
303 sql_insert_function_ptr(name, "(struct module)->init");
304 else
305 sql_insert_function_ptr(name, "(struct module)->exit");
306 free_string(name);
307 if (count >= 2)
308 return;
309 } END_FOR_EACH_PTR_REVERSE(sym);
310 }
311
312 static void match_end_file(struct symbol_list *sym_list)
313 {
314 struct symbol *sym;
315
316 /* find the last static symbol in the file */
317 FOR_EACH_PTR_REVERSE(sym_list, sym) {
318 if (!(sym->ctype.modifiers & MOD_STATIC))
319 continue;
320 if (!sym->scope)
321 continue;
322 find_module_init_exit(sym->scope->symbols);
323 return;
324 } END_FOR_EACH_PTR_REVERSE(sym);
325 }
326
327 static struct expression *get_val_expr(struct expression *expr)
328 {
329 struct symbol *sym, *val;
330
331 if (expr->type != EXPR_DEREF)
332 return NULL;
333 expr = expr->deref;
334 if (expr->type != EXPR_SYMBOL)
335 return NULL;
336 if (strcmp(expr->symbol_name->name, "__u") != 0)
337 return NULL;
338 sym = get_base_type(expr->symbol);
339 val = first_ptr_list((struct ptr_list *)sym->symbol_list);
340 if (!val || strcmp(val->ident->name, "__val") != 0)
341 return NULL;
342 return member_expression(expr, '.', val->ident);
343 }
344
345 static void match__write_once_size(const char *fn, struct expression *call,
346 void *unused)
347 {
348 struct expression *dest, *data, *assign;
349 struct range_list *rl;
350
351 dest = get_argument_from_call_expr(call->args, 0);
352 if (dest->type != EXPR_PREOP || dest->op != '&')
353 return;
354 dest = strip_expr(dest->unop);
355
356 data = get_argument_from_call_expr(call->args, 1);
357 data = get_val_expr(data);
358 if (!data)
359 return;
360 get_absolute_rl(data, &rl);
361 assign = assign_expression(dest, '=', data);
362
363 __in_fake_assign++;
364 __split_expr(assign);
365 __in_fake_assign--;
366 }
367
368 static void match__read_once_size(const char *fn, struct expression *call,
369 void *unused)
370 {
371 struct expression *dest, *data, *assign;
372 struct symbol *type, *val_sym;
373
374 /*
375 * We want to change:
376 * __read_once_size_nocheck(&(x), __u.__c, sizeof(x));
377 * into a fake assignment:
378 * __u.val = x;
379 *
380 */
381
382 data = get_argument_from_call_expr(call->args, 0);
383 if (data->type != EXPR_PREOP || data->op != '&')
384 return;
385 data = strip_parens(data->unop);
386
387 dest = get_argument_from_call_expr(call->args, 1);
388 if (dest->type != EXPR_DEREF || dest->op != '.')
389 return;
390 if (!dest->member || strcmp(dest->member->name, "__c") != 0)
391 return;
392 dest = dest->deref;
393 type = get_type(dest);
394 if (!type)
395 return;
396 val_sym = first_ptr_list((struct ptr_list *)type->symbol_list);
397 dest = member_expression(dest, '.', val_sym->ident);
398
399 assign = assign_expression(dest, '=', data);
400 __in_fake_assign++;
401 __split_expr(assign);
402 __in_fake_assign--;
403 }
404
405 bool is_ignored_kernel_data(const char *name)
406 {
407 if (option_project != PROJ_KERNEL)
408 return false;
409
410 /*
411 * On the file I was looking at lockdep was 25% of the DB.
412 */
413 if (strstr(name, ".dep_map."))
414 return true;
415 if (strstr(name, ".lockdep_map."))
416 return true;
417 return false;
418 }
419
420 void check_kernel(int id)
421 {
422 if (option_project != PROJ_KERNEL)
423 return;
424
425 err_ptr_min.type = &ptr_ctype;
426 err_ptr_min.value = -4095;
427 err_ptr_max.type = &ptr_ctype;
428 err_ptr_max.value = -1l;
429 null_ptr.type = &ptr_ctype;
430 null_ptr.value = 0;
431
432 err_ptr_min = sval_cast(&ptr_ctype, err_ptr_min);
433 err_ptr_max = sval_cast(&ptr_ctype, err_ptr_max);
434
435 add_implied_return_hook("ERR_PTR", &implied_err_cast_return, NULL);
436 add_implied_return_hook("ERR_CAST", &implied_err_cast_return, NULL);
437 add_implied_return_hook("PTR_ERR", &implied_err_cast_return, NULL);
438 add_hook(hack_ERR_PTR, AFTER_DEF_HOOK);
439 return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_param_valid_ptr, (void *)0);
440 return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_param_err_or_null, (void *)0);
441 return_implies_state("IS_ERR", 0, 0, &match_not_err, NULL);
442 return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
443 return_implies_state("tomoyo_memory_ok", 1, 1, &match_param_valid_ptr, (void *)0);
444
445 add_macro_assign_hook_extra("container_of", &match_container_of_macro, NULL);
446 add_hook(match_container_of, ASSIGNMENT_HOOK);
447
448 add_implied_return_hook("find_next_bit", &match_next_bit, NULL);
449 add_implied_return_hook("find_next_zero_bit", &match_next_bit, NULL);
450 add_implied_return_hook("find_first_bit", &match_next_bit, NULL);
451 add_implied_return_hook("find_first_zero_bit", &match_next_bit, NULL);
452
453 add_implied_return_hook("fls", &match_fls, NULL);
454 add_implied_return_hook("fls64", &match_fls, NULL);
455
456 add_function_hook("__ftrace_bad_type", &__match_nullify_path_hook, NULL);
457 add_function_hook("__write_once_size", &match__write_once_size, NULL);
458
459 add_function_hook("__read_once_size", &match__read_once_size, NULL);
460 add_function_hook("__read_once_size_nocheck", &match__read_once_size, NULL);
461
462 if (option_info)
463 add_hook(match_end_file, END_FILE_HOOK);
464 }