check_unwind.c

   1 /*
   2  * smatch/check_unwind.c
   3  *
   4  * Copyright (C) 2010 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * This is a kernel check to make sure we unwind everything on
  12  * on errors.
  13  *
  14  */
  15
  16 #include "smatch.h"
  17 #include "smatch_extra.h"
  18 #include "smatch_slist.h"
  19
  20 #define EBUSY 16
  21 #define MAX_ERRNO 4095
  22
  23 static int my_id;
  24
  25 STATE(allocated);
  26 STATE(unallocated);
  27
  28 /* state of unwind function */
  29 STATE(called);
  30
  31 static int was_passed_as_param(struct expression *expr)
  32 {
  33         char *name;
  34         struct symbol *sym;
  35         struct symbol *arg;
  36
  37         name = get_variable_from_expr(expr, &sym);
  38         if (!name)
  39                 return 0;
  40         free_string(name);
  41
  42         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
  43                 if (arg == sym)
  44                         return 1;
  45         } END_FOR_EACH_PTR(arg);
  46         return 0;
  47 }
  48
  49 static void print_unwind_functions(const char *fn, struct expression *expr, void *_arg_no)
  50 {
  51         struct expression *arg_expr;
  52         int arg_no = (int)_arg_no;
  53         static struct symbol *last_printed = NULL;
  54
  55         arg_expr = get_argument_from_call_expr(expr->args, arg_no);
  56         if (!was_passed_as_param(arg_expr))
  57                 return;
  58         if (last_printed == cur_func_sym)
  59                 return;
  60         last_printed = cur_func_sym;
  61         sm_msg("info: is unwind function");
  62 }
  63
  64 static void request_granted(const char *fn, struct expression *call_expr,
  65                         struct expression *assign_expr, void *_arg_no)
  66 {
  67         struct expression *arg_expr;
  68         int arg_no = (int)_arg_no;
  69
  70         if (arg_no == -1)
  71                 arg_expr = assign_expr->left;
  72         else
  73                 arg_expr = get_argument_from_call_expr(call_expr->args, arg_no);
  74         set_state_expr(my_id, arg_expr, &allocated);
  75 }
  76
  77 static void request_denied(const char *fn, struct expression *call_expr,
  78                         struct expression *assign_expr, void *_arg_no)
  79 {
  80         struct expression *arg_expr;
  81         int arg_no = (int)_arg_no;
  82
  83         if (arg_no == -1)
  84                 arg_expr = assign_expr->left;
  85         else
  86                 arg_expr = get_argument_from_call_expr(call_expr->args, arg_no);
  87         set_state_expr(my_id, arg_expr, &unallocated);
  88 }
  89
  90 static void match_release(const char *fn, struct expression *expr, void *_arg_no)
  91 {
  92         struct expression *arg_expr;
  93         int arg_no = (int)_arg_no;
  94
  95         arg_expr = get_argument_from_call_expr(expr->args, arg_no);
  96         if (get_state_expr(my_id, arg_expr))
  97                 set_state_expr(my_id, arg_expr, &unallocated);
  98         set_equiv_state_expr(my_id, arg_expr, &unallocated);
  99 }
 100
 101 static void match_unwind_function(const char *fn, struct expression *expr, void *unused)
 102 {
 103         set_state(my_id, "unwind_function", NULL, &called);
 104 }
 105
 106 static int func_returns_int()
 107 {
 108         struct symbol *type;
 109
 110         type = get_base_type(cur_func_sym);
 111         if (!type || type->type != SYM_FN)
 112                 return 0;
 113         type = get_base_type(type);
 114         if (type->ctype.base_type == &int_type) {
 115                 return 1;
 116         }
 117         return 0;
 118 }
 119
 120 static void match_return(struct expression *ret_value)
 121 {
 122         struct state_list *slist;
 123         struct sm_state *tmp;
 124
 125         if (!func_returns_int())
 126                 return;
 127         if (!implied_not_equal(ret_value, 0))
 128                 return;
 129         if (get_state(my_id, "unwind_function", NULL) == &called)
 130                 return;
 131
 132         slist = get_all_states(my_id);
 133         FOR_EACH_PTR(slist, tmp) {
 134                 if (slist_has_state(tmp->possible, &allocated))
 135                         sm_msg("warn: '%s' was not released on error", tmp->name);
 136         } END_FOR_EACH_PTR(tmp);
 137         free_slist(&slist);
 138 }
 139
 140 static void register_unwind_functions(void)
 141 {
 142         struct token *token;
 143         const char *func;
 144
 145         token = get_tokens_file("kernel.unwind_functions");
 146         if (!token)
 147                 return;
 148         if (token_type(token) != TOKEN_STREAMBEGIN)
 149                 return;
 150         token = token->next;
 151         while (token_type(token) != TOKEN_STREAMEND) {
 152                 if (token_type(token) != TOKEN_IDENT)
 153                         return;
 154                 func = show_ident(token->ident);
 155                 add_function_hook(func, &match_unwind_function, NULL);
 156                 token = token->next;
 157         }
 158         clear_token_alloc();
 159 }
 160
 161 void check_unwind(int id)
 162 {
 163         if (option_project != PROJ_KERNEL)
 164                 return;
 165         my_id = id;
 166
 167         register_unwind_functions();
 168
 169         return_implies_state("request_resource", 0, 0, &request_granted, INT_PTR(1));
 170         return_implies_state("request_resource", -EBUSY, -EBUSY, &request_denied, INT_PTR(1));
 171         add_function_hook("release_resource", &match_release, INT_PTR(0));
 172
 173         return_implies_state("__request_region", 1, POINTER_MAX, &request_granted, INT_PTR(1));
 174         return_implies_state("__request_region", 0, 0, &request_denied, INT_PTR(1));
 175         add_function_hook("__release_region", &match_release, INT_PTR(1));
 176
 177         return_implies_state("ioremap", 1, POINTER_MAX, &request_granted, INT_PTR(-1));
 178         return_implies_state("ioremap", 0, 0, &request_denied, INT_PTR(-1));
 179         add_function_hook("iounmap", &match_release, INT_PTR(0));
 180
 181         return_implies_state("pci_iomap", 1, POINTER_MAX, &request_granted, INT_PTR(-1));
 182         return_implies_state("pci_iomap", 0, 0, &request_denied, INT_PTR(-1));
 183         add_function_hook("pci_iounmap", &match_release, INT_PTR(1));
 184
 185         return_implies_state("__create_workqueue_key", 1, POINTER_MAX, &request_granted,
 186                         INT_PTR(-1));
 187         return_implies_state("__create_workqueue_key", 0, 0, &request_denied, INT_PTR(-1));
 188         add_function_hook("destroy_workqueue", &match_release, INT_PTR(0));
 189
 190         return_implies_state("request_irq", 0, 0, &request_granted, INT_PTR(0));
 191         return_implies_state("request_irq", -MAX_ERRNO, -1, &request_denied, INT_PTR(0));
 192         add_function_hook("free_irq", &match_release, INT_PTR(0));
 193
 194         return_implies_state("register_netdev", 0, 0, &request_granted, INT_PTR(0));
 195         return_implies_state("register_netdev", -MAX_ERRNO, -1, &request_denied, INT_PTR(0));
 196         add_function_hook("unregister_netdev", &match_release, INT_PTR(0));
 197
 198         return_implies_state("misc_register", 0, 0, &request_granted, INT_PTR(0));
 199         return_implies_state("misc_register", -MAX_ERRNO, -1, &request_denied, INT_PTR(0));
 200         add_function_hook("misc_deregister", &match_release, INT_PTR(0));
 201
 202         add_hook(&match_return, RETURN_HOOK);
 203
 204         if (option_info)
 205                 add_function_hook("free_irq", &print_unwind_functions, INT_PTR(0));
 206 }