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 int is_arg(struct expression *expr)
  35 {
  36         struct symbol *arg;
  37
  38         if (expr->type != EXPR_SYMBOL)
  39                 return 0;
  40
  41         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
  42                 if (arg == expr->symbol)
  43                         return 1;
  44         } END_FOR_EACH_PTR(arg);
  45         return 0;
  46 }
  47
  48 static void set_ignore(struct sm_state *sm, struct expression *mod_expr)
  49 {
  50         if (sm->state == &freed)
  51                 return;
  52         set_state(my_id, sm->name, sm->sym, &ignore);
  53 }
  54
  55 static void match_function_def(struct symbol *sym)
  56 {
  57         struct symbol *arg;
  58         int i;
  59
  60         i = -1;
  61         FOR_EACH_PTR(sym->ctype.base_type->arguments, arg) {
  62                 i++;
  63                 if (!arg->ident)
  64                         continue;
  65                 set_state(my_id, arg->ident->name, arg, &param);
  66         } END_FOR_EACH_PTR(arg);
  67 }
  68
  69 static void freed_variable(struct expression *expr)
  70 {
  71         struct sm_state *sm;
  72
  73         expr = strip_expr(expr);
  74         if (!is_arg(expr))
  75                 return;
  76
  77         sm = get_sm_state_expr(my_id, expr);
  78         if (sm && slist_has_state(sm->possible, &ignore))
  79                 return;
  80         set_state_expr(my_id, expr, &freed);
  81 }
  82
  83 static void match_free(const char *fn, struct expression *expr, void *param)
  84 {
  85         struct expression *arg;
  86
  87         arg = get_argument_from_call_expr(expr->args, PTR_INT(param));
  88         if (!arg)
  89                 return;
  90         freed_variable(arg);
  91 }
  92
  93 static void set_param_freed(struct expression *arg, char *key, char *unused)
  94 {
  95         /* XXX FIXME: call_implies has been updated with more information */
  96         if (strcmp(key, "$$") != 0)
  97                 return;
  98         freed_variable(arg);
  99 }
 100
 101 static void process_states(struct stree *stree)
 102 {
 103         struct symbol *arg;
 104         int i;
 105
 106         i = -1;
 107         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 108                 i++;
 109                 if (!arg->ident)
 110                         continue;
 111                 if (get_state_stree(stree, my_id, arg->ident->name, arg) == &freed)
 112                         sql_insert_call_implies(PARAM_FREED, i, "$$", "1");
 113         } END_FOR_EACH_PTR(arg);
 114 }
 115
 116 void check_frees_param(int id)
 117 {
 118         my_id = id;
 119
 120         add_hook(&match_function_def, FUNC_DEF_HOOK);
 121
 122         if (option_project == PROJ_KERNEL) {
 123                 add_function_hook("kfree", &match_free, INT_PTR(0));
 124                 add_function_hook("kmem_cache_free", &match_free, INT_PTR(1));
 125         } else {
 126                 add_function_hook("free", &match_free, INT_PTR(0));
 127         }
 128
 129         select_call_implies_hook(PARAM_FREED, &set_param_freed);
 130         add_modification_hook(my_id, &set_ignore);
 131
 132         all_return_states_hook(&process_states);
 133 }