check_frees_argument.c

   1 /*
   2  * sparse/check_frees_argument.c
   3  *
   4  * Copyright (C) 2009 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * This script is for finding functions like hcd_buffer_free() which free
  12  * their arguments.  After running it, add those functions to check_memory.c
  13  */
  14
  15 #include "smatch.h"
  16 #include "smatch_slist.h"
  17
  18 static int my_id;
  19
  20 STATE(freed);
  21
  22 static struct symbol *this_func;
  23 static struct tracker_list *freed_args = NULL;
  24
  25 static void match_function_def(struct symbol *sym)
  26 {
  27         this_func = sym;
  28 }
  29
  30 static int is_arg(char *name, struct symbol *sym)
  31 {
  32         struct symbol *arg;
  33         const char *arg_name;
  34
  35         FOR_EACH_PTR(this_func->ctype.base_type->arguments, arg) {
  36                 arg_name = (arg->ident?arg->ident->name:"-");
  37                 if (sym == arg && !strcmp(name, arg_name))
  38                         return 1;
  39         } END_FOR_EACH_PTR(arg);
  40         return 0;
  41 }
  42
  43 static void match_kfree(const char *fn, struct expression *expr, void *info)
  44 {
  45         struct expression *tmp;
  46         struct symbol *sym;
  47         char *name;
  48
  49         tmp = get_argument_from_call_expr(expr->args, 0);
  50         tmp = strip_expr(tmp);
  51         name = get_variable_from_expr(tmp, &sym);
  52         if (is_arg(name, sym)) {
  53                 set_state(my_id, name, sym, &freed);
  54         }
  55         free_string(name);
  56 }
  57
  58 static int return_count = 0;
  59 static void match_return(struct expression *ret_value)
  60 {
  61         struct state_list *slist;
  62         struct sm_state *tmp;
  63         struct tracker *tracker;
  64
  65         if (!return_count) {
  66                 slist = get_all_states(my_id);
  67                 FOR_EACH_PTR(slist, tmp) {
  68                         if (tmp->state == &freed)
  69                                 add_tracker(&freed_args, my_id, tmp->name,
  70                                             tmp->sym);
  71                 } END_FOR_EACH_PTR(tmp);
  72                 free_slist(&slist);
  73         } else {
  74                 FOR_EACH_PTR(freed_args, tracker) {
  75                         tmp = get_sm_state(my_id, tracker->name, tracker->sym);
  76                         if (tmp && tmp->state != &freed)
  77                                 del_tracker(&freed_args, my_id, tracker->name,
  78                                             tracker->sym);
  79                 } END_FOR_EACH_PTR(tracker);
  80
  81         }
  82 }
  83
  84 static void print_arg(struct symbol *sym)
  85 {
  86         struct symbol *arg;
  87         int i = 0;
  88
  89         FOR_EACH_PTR(this_func->ctype.base_type->arguments, arg) {
  90                 if (sym == arg) {
  91                         sm_printf("info: free_arg %s %d\n", get_function(), i);
  92                         return;
  93                 }
  94                 i++;
  95         } END_FOR_EACH_PTR(arg);
  96 }
  97
  98 static void match_end_func(struct symbol *sym)
  99 {
 100         struct tracker *tracker;
 101
 102         if (is_reachable())
 103                 match_return(NULL);
 104
 105         FOR_EACH_PTR(freed_args, tracker) {
 106                 print_arg(tracker->sym);
 107         } END_FOR_EACH_PTR(tracker);
 108
 109         free_trackers_and_list(&freed_args);
 110         return_count = 0;
 111 }
 112
 113 void check_frees_argument(int id)
 114 {
 115         if (!option_spammy)
 116                 return;
 117
 118         my_id = id;
 119         add_hook(&match_function_def, FUNC_DEF_HOOK);
 120         if (option_project == PROJ_KERNEL)
 121                 add_function_hook("kfree", &match_kfree, NULL);
 122         else
 123                 add_function_hook("free", &match_kfree, NULL);
 124         add_hook(&match_return, RETURN_HOOK);
 125         add_hook(&match_end_func, END_FUNC_HOOK);
 126 }