check_frees_param.c

   1 /*
   2  * Copyright (C) 2014 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 file is sort of like check_dereferences_param.c.  In theory the one
  20  * difference should be that the param is NULL it should still be counted as a
  21  * free.  But for now I don't handle that case.
  22  */
  23
  24 #include "smatch.h"
  25 #include "smatch_extra.h"
  26 #include "smatch_slist.h"
  27
  28 static int my_id;
  29
  30 STATE(freed);
  31 STATE(ignore);
  32
  33 static void set_ignore(struct sm_state *sm, struct expression *mod_expr)
  34 {
  35         set_state(my_id, sm->name, sm->sym, &ignore);
  36 }
  37
  38 static void freed_variable(struct expression *expr)
  39 {
  40         struct sm_state *sm;
  41
  42         expr = strip_expr(expr);
  43         if (get_param_num(expr) < 0)
  44                 return;
  45
  46         sm = get_sm_state_expr(my_id, expr);
  47         if (sm && slist_has_state(sm->possible, &ignore))
  48                 return;
  49         set_state_expr(my_id, expr, &freed);
  50 }
  51
  52 static void match_free(const char *fn, struct expression *expr, void *param)
  53 {
  54         struct expression *arg;
  55
  56         arg = get_argument_from_call_expr(expr->args, PTR_INT(param));
  57         if (!arg)
  58                 return;
  59         freed_variable(arg);
  60 }
  61
  62 static void set_param_freed(struct expression *call, struct expression *arg, char *key, char *unused)
  63 {
  64         /* XXX FIXME: return_implies has been updated with more information */
  65         if (strcmp(key, "$") != 0)
  66                 return;
  67         freed_variable(arg);
  68 }
  69
  70 static void process_states(void)
  71 {
  72         struct sm_state *sm;
  73         int param;
  74         const char *param_name;
  75
  76         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
  77                 if (sm->state != &freed)
  78                         continue;
  79                 param = get_param_num_from_sym(sm->sym);
  80                 if (param < 0)
  81                         continue;
  82                 param_name = get_param_name(sm);
  83                 if (!param_name)
  84                         continue;
  85                 sql_insert_return_implies(PARAM_FREED, param, param_name, "1");
  86         } END_FOR_EACH_SM(sm);
  87
  88 }
  89
  90 void check_frees_param(int id)
  91 {
  92         my_id = id;
  93
  94         if (option_project == PROJ_KERNEL) {
  95                 /* The kernel uses check_frees_param_strict.c */
  96                 return;
  97         }
  98
  99         add_function_hook("free", &match_free, INT_PTR(0));
 100
 101         select_return_implies_hook(PARAM_FREED, &set_param_freed);
 102         add_modification_hook(my_id, &set_ignore);
 103
 104         all_return_states_hook(&process_states);
 105 }