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 STATE(param);
  33
  34 static void set_ignore(struct sm_state *sm, struct expression *mod_expr)
  35 {
  36         if (sm->state == &freed)
  37                 return;
  38         set_state(my_id, sm->name, sm->sym, &ignore);
  39 }
  40
  41 static void match_function_def(struct symbol *sym)
  42 {
  43         struct symbol *arg;
  44         int i;
  45
  46         i = -1;
  47         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
  48                 i++;
  49                 if (!arg->ident)
  50                         continue;
  51                 set_state(my_id, arg->ident->name, arg, &param);
  52         } END_FOR_EACH_PTR(arg);
  53 }
  54
  55 static void freed_variable(struct expression *expr)
  56 {
  57         struct sm_state *sm;
  58
  59         expr = strip_expr(expr);
  60         if (get_param_num(expr) < 0)
  61                 return;
  62
  63         sm = get_sm_state_expr(my_id, expr);
  64         if (sm && slist_has_state(sm->possible, &ignore))
  65                 return;
  66         set_state_expr(my_id, expr, &freed);
  67 }
  68
  69 static void match_free(const char *fn, struct expression *expr, void *param)
  70 {
  71         struct expression *arg;
  72
  73         arg = get_argument_from_call_expr(expr->args, PTR_INT(param));
  74         if (!arg)
  75                 return;
  76         freed_variable(arg);
  77 }
  78
  79 static void set_param_freed(struct expression *arg, char *key, char *unused)
  80 {
  81         /* XXX FIXME: call_implies has been updated with more information */
  82         if (strcmp(key, "$") != 0)
  83                 return;
  84         freed_variable(arg);
  85 }
  86
  87 static void process_states(struct stree *stree)
  88 {
  89         struct sm_state *sm;
  90         int param;
  91         const char *param_name;
  92
  93         FOR_EACH_MY_SM(my_id, stree, sm) {
  94                 if (sm->state != &freed)
  95                         continue;
  96                 param = get_param_num_from_sym(sm->sym);
  97                 if (param < 0)
  98                         continue;
  99                 param_name = get_param_name(sm);
 100                 if (!param_name)
 101                         continue;
 102                 sql_insert_call_implies(PARAM_FREED, param, param_name, "1");
 103         } END_FOR_EACH_SM(sm);
 104
 105 }
 106
 107 void check_frees_param(int id)
 108 {
 109         my_id = id;
 110
 111         add_hook(&match_function_def, FUNC_DEF_HOOK);
 112
 113         if (option_project == PROJ_KERNEL) {
 114                 add_function_hook("kfree", &match_free, INT_PTR(0));
 115                 add_function_hook("kmem_cache_free", &match_free, INT_PTR(1));
 116         } else {
 117                 add_function_hook("free", &match_free, INT_PTR(0));
 118         }
 119
 120         select_call_implies_hook(PARAM_FREED, &set_param_freed);
 121         add_modification_hook(my_id, &set_ignore);
 122
 123         all_return_states_hook(&process_states);
 124 }