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(maybe_freed);
  32 STATE(ignore);
  33
  34 static void set_ignore(struct sm_state *sm, struct expression *mod_expr)
  35 {
  36         set_state(my_id, sm->name, sm->sym, &ignore);
  37 }
  38
  39 static void freed_variable(struct expression *expr)
  40 {
  41         struct sm_state *sm;
  42
  43         expr = strip_expr(expr);
  44         if (get_param_num(expr) < 0)
  45                 return;
  46
  47         sm = get_sm_state_expr(my_id, expr);
  48         if (sm && slist_has_state(sm->possible, &ignore))
  49                 return;
  50         set_state_expr(my_id, expr, &freed);
  51 }
  52
  53 static void match_free(const char *fn, struct expression *expr, void *param)
  54 {
  55         struct expression *arg;
  56
  57         arg = get_argument_from_call_expr(expr->args, PTR_INT(param));
  58         if (!arg)
  59                 return;
  60         freed_variable(arg);
  61 }
  62
  63 static void set_param_freed(struct expression *call, struct expression *arg, char *key, char *unused)
  64 {
  65         /* XXX FIXME: return_implies has been updated with more information */
  66         if (strcmp(key, "$") != 0)
  67                 return;
  68         freed_variable(arg);
  69 }
  70
  71 static void process_states(void)
  72 {
  73         struct sm_state *sm;
  74         int param;
  75         const char *param_name;
  76
  77         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
  78                 // FIXME: how can this be maybe_freed?
  79                 if (sm->state != &freed && sm->state != &maybe_freed)
  80                         continue;
  81                 param = get_param_num_from_sym(sm->sym);
  82                 if (param < 0)
  83                         continue;
  84                 param_name = get_param_name(sm);
  85                 if (!param_name)
  86                         continue;
  87                 sql_insert_return_implies(
  88                         (sm->state == &freed) ? PARAM_FREED : MAYBE_FREED,
  89                         param, param_name, "1");
  90         } END_FOR_EACH_SM(sm);
  91
  92 }
  93
  94 void check_frees_param(int id)
  95 {
  96         my_id = id;
  97
  98         if (option_project == PROJ_KERNEL) {
  99                 /* The kernel uses check_frees_param_strict.c */
 100                 return;
 101         }
 102
 103         add_function_hook("free", &match_free, INT_PTR(0));
 104
 105         select_return_implies_hook(PARAM_FREED, &set_param_freed);
 106         add_modification_hook(my_id, &set_ignore);
 107
 108         all_return_states_hook(&process_states);
 109 }