11f5207bJohn Levon/*
21f5207bJohn Levon * Copyright (C) 2009 Dan Carpenter.
31f5207bJohn Levon *
41f5207bJohn Levon * This program is free software; you can redistribute it and/or
51f5207bJohn Levon * modify it under the terms of the GNU General Public License
61f5207bJohn Levon * as published by the Free Software Foundation; either version 2
71f5207bJohn Levon * of the License, or (at your option) any later version.
81f5207bJohn Levon *
91f5207bJohn Levon * This program is distributed in the hope that it will be useful,
101f5207bJohn Levon * but WITHOUT ANY WARRANTY; without even the implied warranty of
121f5207bJohn Levon * GNU General Public License for more details.
131f5207bJohn Levon *
141f5207bJohn Levon * You should have received a copy of the GNU General Public License
151f5207bJohn Levon * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
161f5207bJohn Levon */
171f5207bJohn Levon
181f5207bJohn Levon#include "smatch.h"
191f5207bJohn Levon#include "smatch_slist.h"
201f5207bJohn Levon#include "smatch_extra.h"
211f5207bJohn Levon
221f5207bJohn Levonstatic int my_id;
231f5207bJohn Levon
241f5207bJohn LevonSTATE(err_ptr);
251f5207bJohn LevonSTATE(checked);
261f5207bJohn Levon
271f5207bJohn Levonstatic sval_t err_ptr_min = {
281f5207bJohn Levon	.type = &int_ctype,
291f5207bJohn Levon	{.value = -4095},
301f5207bJohn Levon};
311f5207bJohn Levon
321f5207bJohn Levonstatic sval_t err_ptr_max = {
331f5207bJohn Levon	.type = &int_ctype,
341f5207bJohn Levon	{.value = -1},
351f5207bJohn Levon};
361f5207bJohn Levon
371f5207bJohn Levonstruct range_list *err_ptr_rl;
381f5207bJohn Levon
391f5207bJohn Levonstatic void ok_to_use(struct sm_state *sm, struct expression *mod_expr)
401f5207bJohn Levon{
411f5207bJohn Levon	if (sm->state != &checked)
421f5207bJohn Levon		set_state(my_id, sm->name, sm->sym, &checked);
431f5207bJohn Levon}
441f5207bJohn Levon
451f5207bJohn Levonstatic void check_is_err_ptr(struct expression *expr)
461f5207bJohn Levon{
471f5207bJohn Levon	struct sm_state *sm;
481f5207bJohn Levon	struct range_list *rl;
491f5207bJohn Levon
501f5207bJohn Levon	sm = get_sm_state_expr(my_id, expr);
511f5207bJohn Levon	if (!sm)
521f5207bJohn Levon		return;
531f5207bJohn Levon
541f5207bJohn Levon	if (!slist_has_state(sm->possible, &err_ptr))
551f5207bJohn Levon		return;
561f5207bJohn Levon
571f5207bJohn Levon	get_absolute_rl(expr, &rl);
581f5207bJohn Levon	if (!possibly_true_rl(rl, SPECIAL_EQUAL, err_ptr_rl))
591f5207bJohn Levon		return;
601f5207bJohn Levon
611f5207bJohn Levon	sm_error("'%s' dereferencing possible ERR_PTR()", sm->name);
621f5207bJohn Levon	set_state(my_id, sm->name, sm->sym, &checked);
631f5207bJohn Levon}
641f5207bJohn Levon
651f5207bJohn Levonstatic void match_returns_err_ptr(const char *fn, struct expression *expr,
661f5207bJohn Levon				void *info)
671f5207bJohn Levon{
681f5207bJohn Levon	set_state_expr(my_id, expr->left, &err_ptr);
691f5207bJohn Levon}
701f5207bJohn Levon
711f5207bJohn Levonstatic void set_param_dereferenced(struct expression *call, struct expression *arg, char *key, char *unused)
721f5207bJohn Levon{
731f5207bJohn Levon	struct sm_state *sm;
741f5207bJohn Levon	struct smatch_state *estate;
751f5207bJohn Levon	struct symbol *sym;
761f5207bJohn Levon	char *name;
771f5207bJohn Levon
781f5207bJohn Levon	name = get_variable_from_key(arg, key, &sym);
791f5207bJohn Levon	if (!name || !sym)
801f5207bJohn Levon		goto free;
811f5207bJohn Levon
821f5207bJohn Levon	sm = get_sm_state(my_id, name, sym);
831f5207bJohn Levon	if (!sm)
841f5207bJohn Levon		goto free;
851f5207bJohn Levon
861f5207bJohn Levon	if (!slist_has_state(sm->possible, &err_ptr))
871f5207bJohn Levon		goto free;
881f5207bJohn Levon
891f5207bJohn Levon	estate = get_state(SMATCH_EXTRA, name, sym);
901f5207bJohn Levon	if (!estate || !possibly_true_rl(estate_rl(estate), SPECIAL_EQUAL, err_ptr_rl))
911f5207bJohn Levon		goto free;
921f5207bJohn Levon
931f5207bJohn Levon	sm_error("'%s' dereferencing possible ERR_PTR()", sm->name);
941f5207bJohn Levon	set_state(my_id, sm->name, sm->sym, &checked);
951f5207bJohn Levon
961f5207bJohn Levonfree:
971f5207bJohn Levon	free_string(name);
981f5207bJohn Levon}
991f5207bJohn Levon
1001f5207bJohn Levonstatic void match_checked(const char *fn, struct expression *call_expr,
1011f5207bJohn Levon			struct expression *assign_expr, void *unused)
1021f5207bJohn Levon{
1031f5207bJohn Levon	struct expression *arg;
1041f5207bJohn Levon
1051f5207bJohn Levon	arg = get_argument_from_call_expr(call_expr->args, 0);
1061f5207bJohn Levon	arg = strip_expr(arg);
1071f5207bJohn Levon	while (arg->type == EXPR_ASSIGNMENT)
1081f5207bJohn Levon		arg = strip_expr(arg->left);
1091f5207bJohn Levon	set_state_expr(my_id, arg, &checked);
1101f5207bJohn Levon}
1111f5207bJohn Levon
1121f5207bJohn Levonstatic void match_err(const char *fn, struct expression *call_expr,
1131f5207bJohn Levon			struct expression *assign_expr, void *unused)
1141f5207bJohn Levon{
1151f5207bJohn Levon	struct expression *arg;
1161f5207bJohn Levon
1171f5207bJohn Levon	arg = get_argument_from_call_expr(call_expr->args, 0);
1181f5207bJohn Levon	arg = strip_expr(arg);
1191f5207bJohn Levon	while (arg->type == EXPR_ASSIGNMENT)
1201f5207bJohn Levon		arg = strip_expr(arg->left);
1211f5207bJohn Levon	set_state_expr(my_id, arg, &err_ptr);
1221f5207bJohn Levon}
1231f5207bJohn Levon
1241f5207bJohn Levonstatic void match_dereferences(struct expression *expr)
1251f5207bJohn Levon{
1261f5207bJohn Levon	if (expr->type != EXPR_PREOP)
1271f5207bJohn Levon		return;
1281f5207bJohn Levon	check_is_err_ptr(expr->unop);
1291f5207bJohn Levon}
1301f5207bJohn Levon
1311f5207bJohn Levonstatic void match_kfree(const char *fn, struct expression *expr, void *_arg_nr)
1321f5207bJohn Levon{
1331f5207bJohn Levon	int arg_nr = PTR_INT(_arg_nr);
1341f5207bJohn Levon	struct expression *arg;
1351f5207bJohn Levon
1361f5207bJohn Levon	arg = get_argument_from_call_expr(expr->args, arg_nr);
1371f5207bJohn Levon	check_is_err_ptr(arg);
1381f5207bJohn Levon}
1391f5207bJohn Levon
1401f5207bJohn Levonstatic void match_condition(struct expression *expr)
1411f5207bJohn Levon{
1421f5207bJohn Levon	if (expr->type == EXPR_ASSIGNMENT) {
1431f5207bJohn Levon		match_condition(expr->right);
1441f5207bJohn Levon		match_condition(expr->left);
1451f5207bJohn Levon	}
1461f5207bJohn Levon	if (!get_state_expr(my_id, expr))
1471f5207bJohn Levon		return;
1481f5207bJohn Levon	/* If we know the variable is zero that means it's not an ERR_PTR */
1491f5207bJohn Levon	set_true_false_states_expr(my_id, expr, NULL, &checked);
1501f5207bJohn Levon}
1511f5207bJohn Levon
1521f5207bJohn Levonstatic void register_err_ptr_funcs(void)
1531f5207bJohn Levon{
1541f5207bJohn Levon	struct token *token;
1551f5207bJohn Levon	const char *func;
1561f5207bJohn Levon
1571f5207bJohn Levon	token = get_tokens_file("kernel.returns_err_ptr");
1581f5207bJohn Levon	if (!token)
1591f5207bJohn Levon		return;
1601f5207bJohn Levon	if (token_type(token) != TOKEN_STREAMBEGIN)
1611f5207bJohn Levon		return;
1621f5207bJohn Levon	token = token->next;
1631f5207bJohn Levon	while (token_type(token) != TOKEN_STREAMEND) {
1641f5207bJohn Levon		if (token_type(token) != TOKEN_IDENT)
1651f5207bJohn Levon			return;
1661f5207bJohn Levon		func = show_ident(token->ident);
1671f5207bJohn Levon		add_function_assign_hook(func, &match_returns_err_ptr, NULL);
1681f5207bJohn Levon		token = token->next;
1691f5207bJohn Levon	}
1701f5207bJohn Levon	clear_token_alloc();
1711f5207bJohn Levon}
1721f5207bJohn Levon
1731f5207bJohn Levonstatic void match_err_ptr_positive_const(const char *fn, struct expression *expr, void *unused)
1741f5207bJohn Levon{
1751f5207bJohn Levon	struct expression *arg;
1761f5207bJohn Levon	sval_t sval;
1771f5207bJohn Levon
1781f5207bJohn Levon	arg = get_argument_from_call_expr(expr->args, 0);
1791f5207bJohn Levon
1801f5207bJohn Levon	if (!get_value(arg, &sval))
1811f5207bJohn Levon		return;
1821f5207bJohn Levon	if (sval_is_positive(sval) && sval_cmp_val(sval, 0) != 0)
1831f5207bJohn Levon		sm_error("passing non negative %s to ERR_PTR", sval_to_str(sval));
1841f5207bJohn Levon}
1851f5207bJohn Levon
1861f5207bJohn Levonstatic void match_err_ptr(const char *fn, struct expression *expr, void *unused)
1871f5207bJohn Levon{
1881f5207bJohn Levon	struct expression *arg;
1891f5207bJohn Levon	struct sm_state *sm;
1901f5207bJohn Levon	struct sm_state *tmp;
1911f5207bJohn Levon	sval_t tmp_min;
1921f5207bJohn Levon	sval_t tmp_max;
1931f5207bJohn Levon	sval_t min = sval_type_max(&llong_ctype);
1941f5207bJohn Levon	sval_t max = sval_type_min(&llong_ctype);
1951f5207bJohn Levon
1961f5207bJohn Levon	arg = get_argument_from_call_expr(expr->args, 0);
1971f5207bJohn Levon	sm = get_sm_state_expr(SMATCH_EXTRA, arg);
1981f5207bJohn Levon	if (!sm)
1991f5207bJohn Levon		return;
2001f5207bJohn Levon	FOR_EACH_PTR(sm->possible, tmp) {
2011f5207bJohn Levon		tmp_min = estate_min(tmp->state);
2021f5207bJohn Levon		if (!sval_is_a_min(tmp_min) && sval_cmp(tmp_min, min) < 0)
2031f5207bJohn Levon			min = tmp_min;
2041f5207bJohn Levon		tmp_max = estate_max(tmp->state);
2051f5207bJohn Levon		if (!sval_is_a_max(tmp_max) && sval_cmp(tmp_max, max) > 0)
2061f5207bJohn Levon			max = tmp_max;
2071f5207bJohn Levon	} END_FOR_EACH_PTR(tmp);
2081f5207bJohn Levon	if (sval_is_negative(min) && sval_cmp_val(min, -4095) < 0)
2091f5207bJohn Levon		sm_error("%s too low for ERR_PTR", sval_to_str(min));
2101f5207bJohn Levon	if (sval_is_positive(max) && sval_cmp_val(max, 0) != 0)
2111f5207bJohn Levon		sm_error("passing non negative %s to ERR_PTR", sval_to_str(max));
2121f5207bJohn Levon}
2131f5207bJohn Levon
2141f5207bJohn Levonvoid check_err_ptr_deref(int id)
2151f5207bJohn Levon{
2161f5207bJohn Levon	if (option_project != PROJ_KERNEL)
2171f5207bJohn Levon		return;
2181f5207bJohn Levon
2191f5207bJohn Levon	my_id = id;
2201f5207bJohn Levon	return_implies_state("IS_ERR", 0, 0, &match_checked, NULL);
2211f5207bJohn Levon	return_implies_state("IS_ERR", 1, 1, &match_err, NULL);
2221f5207bJohn Levon	return_implies_state("IS_ERR_OR_NULL", 0, 0, &match_checked, NULL);
2231f5207bJohn Levon	return_implies_state("IS_ERR_OR_NULL", 1, 1, &match_err, NULL);
2241f5207bJohn Levon	return_implies_state("PTR_RET", 0, 0, &match_checked, NULL);
225efe51d0John Levon	return_implies_state("PTR_RET", -4095, -1, &match_err, NULL);
2261f5207bJohn Levon	register_err_ptr_funcs();
2271f5207bJohn Levon	add_hook(&match_dereferences, DEREF_HOOK);
2281f5207bJohn Levon	add_function_hook("ERR_PTR", &match_err_ptr_positive_const, NULL);
2291f5207bJohn Levon	add_function_hook("ERR_PTR", &match_err_ptr, NULL);
2301f5207bJohn Levon	add_hook(&match_condition, CONDITION_HOOK);
2311f5207bJohn Levon	add_modification_hook(my_id, &ok_to_use);
2321f5207bJohn Levon	add_function_hook("kfree", &match_kfree, INT_PTR(0));
2331f5207bJohn Levon	add_function_hook("brelse", &match_kfree, INT_PTR(0));
2341f5207bJohn Levon	add_function_hook("kmem_cache_free", &match_kfree, INT_PTR(1));
2351f5207bJohn Levon	add_function_hook("vfree", &match_kfree, INT_PTR(0));
2361f5207bJohn Levon
2371f5207bJohn Levon	err_ptr_rl = clone_rl_permanent(alloc_rl(err_ptr_min, err_ptr_max));
2381f5207bJohn Levon
2391f5207bJohn Levon	select_return_implies_hook(DEREFERENCE, &set_param_dereferenced);
2401f5207bJohn Levon}
2411f5207bJohn Levon