check_frees_argument.c

   1 /*
   2  * Copyright (C) 2009 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 script is for finding functions like hcd_buffer_free() which free
  20  * their arguments.  After running it, add those functions to check_memory.c
  21  */
  22
  23 #include "smatch.h"
  24 #include "smatch_slist.h"
  25
  26 static int my_id;
  27
  28 STATE(freed);
  29
  30 static struct symbol *this_func;
  31 static struct tracker_list *freed_args = NULL;
  32
  33 static void match_function_def(struct symbol *sym)
  34 {
  35         this_func = sym;
  36 }
  37
  38 static int is_arg(char *name, struct symbol *sym)
  39 {
  40         struct symbol *arg;
  41         const char *arg_name;
  42
  43         FOR_EACH_PTR(this_func->ctype.base_type->arguments, arg) {
  44                 arg_name = (arg->ident?arg->ident->name:"-");
  45                 if (sym == arg && !strcmp(name, arg_name))
  46                         return 1;
  47         } END_FOR_EACH_PTR(arg);
  48         return 0;
  49 }
  50
  51 static void match_kfree(const char *fn, struct expression *expr, void *info)
  52 {
  53         struct expression *tmp;
  54         struct symbol *sym;
  55         char *name;
  56
  57         tmp = get_argument_from_call_expr(expr->args, 0);
  58         tmp = strip_expr(tmp);
  59         name = expr_to_var_sym(tmp, &sym);
  60         if (is_arg(name, sym)) {
  61                 set_state(my_id, name, sym, &freed);
  62         }
  63         free_string(name);
  64 }
  65
  66 static int return_count = 0;
  67 static void match_return(struct expression *ret_value)
  68 {
  69         struct stree *stree;
  70         struct sm_state *tmp;
  71         struct tracker *tracker;
  72
  73         if (__inline_fn)
  74                 return;
  75
  76         if (!return_count) {
  77                 stree = __get_cur_stree();
  78                 FOR_EACH_MY_SM(my_id, stree, tmp) {
  79                         if (tmp->state == &freed)
  80                                 add_tracker(&freed_args, my_id, tmp->name,
  81                                             tmp->sym);
  82                 } END_FOR_EACH_SM(tmp);
  83         } else {
  84                 FOR_EACH_PTR(freed_args, tracker) {
  85                         tmp = get_sm_state(my_id, tracker->name, tracker->sym);
  86                         if (tmp && tmp->state != &freed)
  87                                 del_tracker(&freed_args, my_id, tracker->name,
  88                                             tracker->sym);
  89                 } END_FOR_EACH_PTR(tracker);
  90         }
  91 }
  92
  93 static void print_arg(struct symbol *sym)
  94 {
  95         struct symbol *arg;
  96         int i = 0;
  97
  98         FOR_EACH_PTR(this_func->ctype.base_type->arguments, arg) {
  99                 if (sym == arg) {
 100                         sm_info("free_arg %s %d", get_function(), i);
 101                         return;
 102                 }
 103                 i++;
 104         } END_FOR_EACH_PTR(arg);
 105 }
 106
 107 static void match_end_func(struct symbol *sym)
 108 {
 109         if (__inline_fn)
 110                 return;
 111         if (is_reachable())
 112                 match_return(NULL);
 113 }
 114
 115 static void match_after_func(struct symbol *sym)
 116 {
 117         struct tracker *tracker;
 118
 119         if (__inline_fn)
 120                 return;
 121
 122         FOR_EACH_PTR(freed_args, tracker) {
 123                 print_arg(tracker->sym);
 124         } END_FOR_EACH_PTR(tracker);
 125
 126         free_trackers_and_list(&freed_args);
 127         return_count = 0;
 128 }
 129
 130 void check_frees_argument(int id)
 131 {
 132         if (!option_info)
 133                 return;
 134
 135         my_id = id;
 136         add_hook(&match_function_def, FUNC_DEF_HOOK);
 137         if (option_project == PROJ_KERNEL)
 138                 add_function_hook("kfree", &match_kfree, NULL);
 139         else
 140                 add_function_hook("free", &match_kfree, NULL);
 141         add_hook(&match_return, RETURN_HOOK);
 142         add_hook(&match_end_func, END_FUNC_HOOK);
 143         add_hook(&match_after_func, AFTER_FUNC_HOOK);
 144 }