check_unwind.c

   1 /*
   2  * Copyright (C) 2010 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 is a kernel check to make sure we unwind everything on
  20  * on errors.
  21  *
  22  */
  23
  24 #include "smatch.h"
  25 #include "smatch_extra.h"
  26 #include "smatch_slist.h"
  27
  28 #define EBUSY 16
  29 #define MAX_ERRNO 4095
  30
  31 static int my_id;
  32
  33 STATE(allocated);
  34 STATE(unallocated);
  35
  36 /* state of unwind function */
  37 STATE(called);
  38
  39 static int was_passed_as_param(struct expression *expr)
  40 {
  41         char *name;
  42         struct symbol *sym;
  43         struct symbol *arg;
  44
  45         name = expr_to_var_sym(expr, &sym);
  46         if (!name)
  47                 return 0;
  48         free_string(name);
  49
  50         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
  51                 if (arg == sym)
  52                         return 1;
  53         } END_FOR_EACH_PTR(arg);
  54         return 0;
  55 }
  56
  57 static void print_unwind_functions(const char *fn, struct expression *expr, void *_arg_no)
  58 {
  59         struct expression *arg_expr;
  60         int arg_no = PTR_INT(_arg_no);
  61         static struct symbol *last_printed = NULL;
  62
  63         arg_expr = get_argument_from_call_expr(expr->args, arg_no);
  64         if (!was_passed_as_param(arg_expr))
  65                 return;
  66         if (last_printed == cur_func_sym)
  67                 return;
  68         last_printed = cur_func_sym;
  69         sm_msg("info: is unwind function");
  70 }
  71
  72 static void request_granted(const char *fn, struct expression *call_expr,
  73                         struct expression *assign_expr, void *_arg_no)
  74 {
  75         struct expression *arg_expr;
  76         int arg_no = PTR_INT(_arg_no);
  77
  78         if (arg_no == -1)
  79                 arg_expr = assign_expr->left;
  80         else
  81                 arg_expr = get_argument_from_call_expr(call_expr->args, arg_no);
  82         set_state_expr(my_id, arg_expr, &allocated);
  83 }
  84
  85 static void request_denied(const char *fn, struct expression *call_expr,
  86                         struct expression *assign_expr, void *_arg_no)
  87 {
  88         struct expression *arg_expr;
  89         int arg_no = PTR_INT(_arg_no);
  90
  91         if (arg_no == -1)
  92                 arg_expr = assign_expr->left;
  93         else
  94                 arg_expr = get_argument_from_call_expr(call_expr->args, arg_no);
  95         set_state_expr(my_id, arg_expr, &unallocated);
  96 }
  97
  98 static void match_release(const char *fn, struct expression *expr, void *_arg_no)
  99 {
 100         struct expression *arg_expr;
 101         int arg_no = PTR_INT(_arg_no);
 102
 103         arg_expr = get_argument_from_call_expr(expr->args, arg_no);
 104         if (get_state_expr(my_id, arg_expr))
 105                 set_state_expr(my_id, arg_expr, &unallocated);
 106         set_equiv_state_expr(my_id, arg_expr, &unallocated);
 107 }
 108
 109 static void match_unwind_function(const char *fn, struct expression *expr, void *unused)
 110 {
 111         set_state(my_id, "unwind_function", NULL, &called);
 112 }
 113
 114 static int func_returns_int(void)
 115 {
 116         struct symbol *type;
 117
 118         type = get_base_type(cur_func_sym);
 119         if (!type || type->type != SYM_FN)
 120                 return 0;
 121         type = get_base_type(type);
 122         if (type->ctype.base_type == &int_type) {
 123                 return 1;
 124         }
 125         return 0;
 126 }
 127
 128 static void match_return(struct expression *ret_value)
 129 {
 130         struct stree *stree;
 131         struct sm_state *tmp;
 132         sval_t sval;
 133
 134         if (!func_returns_int())
 135                 return;
 136         if (get_value(ret_value, &sval) && sval_cmp_val(sval, 0) >= 0)
 137                 return;
 138         if (!implied_not_equal(ret_value, 0))
 139                 return;
 140         if (get_state(my_id, "unwind_function", NULL) == &called)
 141                 return;
 142
 143         stree = __get_cur_stree();
 144         FOR_EACH_MY_SM(my_id, stree, tmp) {
 145                 if (slist_has_state(tmp->possible, &allocated))
 146                         sm_msg("warn: '%s' was not released on error", tmp->name);
 147         } END_FOR_EACH_SM(tmp);
 148 }
 149
 150 static void register_unwind_functions(void)
 151 {
 152         struct token *token;
 153         const char *func;
 154
 155         token = get_tokens_file("kernel.unwind_functions");
 156         if (!token)
 157                 return;
 158         if (token_type(token) != TOKEN_STREAMBEGIN)
 159                 return;
 160         token = token->next;
 161         while (token_type(token) != TOKEN_STREAMEND) {
 162                 if (token_type(token) != TOKEN_IDENT)
 163                         return;
 164                 func = show_ident(token->ident);
 165                 add_function_hook(func, &match_unwind_function, NULL);
 166                 token = token->next;
 167         }
 168         clear_token_alloc();
 169 }
 170
 171 static void release_function_indicator(const char *name)
 172 {
 173         if (!option_info)
 174                 return;
 175         add_function_hook(name, &print_unwind_functions, INT_PTR(0));
 176 }
 177
 178 void check_unwind(int id)
 179 {
 180         if (option_project != PROJ_KERNEL || !option_spammy)
 181                 return;
 182         my_id = id;
 183
 184         register_unwind_functions();
 185
 186         return_implies_state("request_resource", 0, 0, &request_granted, INT_PTR(1));
 187         return_implies_state("request_resource", -EBUSY, -EBUSY, &request_denied, INT_PTR(1));
 188         add_function_hook("release_resource", &match_release, INT_PTR(0));
 189         release_function_indicator("release_resource");
 190
 191         return_implies_state("__request_region", valid_ptr_min, valid_ptr_max, &request_granted, INT_PTR(1));
 192         return_implies_state("__request_region", 0, 0, &request_denied, INT_PTR(1));
 193         add_function_hook("__release_region", &match_release, INT_PTR(1));
 194         release_function_indicator("__release_region");
 195
 196         return_implies_state("ioremap", valid_ptr_min, valid_ptr_max, &request_granted, INT_PTR(-1));
 197         return_implies_state("ioremap", 0, 0, &request_denied, INT_PTR(-1));
 198         add_function_hook("iounmap", &match_release, INT_PTR(0));
 199
 200         return_implies_state("pci_iomap", valid_ptr_min, valid_ptr_max, &request_granted, INT_PTR(-1));
 201         return_implies_state("pci_iomap", 0, 0, &request_denied, INT_PTR(-1));
 202         add_function_hook("pci_iounmap", &match_release, INT_PTR(1));
 203         release_function_indicator("pci_iounmap");
 204
 205         return_implies_state("__create_workqueue_key", valid_ptr_min, valid_ptr_max, &request_granted,
 206                         INT_PTR(-1));
 207         return_implies_state("__create_workqueue_key", 0, 0, &request_denied, INT_PTR(-1));
 208         add_function_hook("destroy_workqueue", &match_release, INT_PTR(0));
 209
 210         return_implies_state("request_irq", 0, 0, &request_granted, INT_PTR(0));
 211         return_implies_state("request_irq", -MAX_ERRNO, -1, &request_denied, INT_PTR(0));
 212         add_function_hook("free_irq", &match_release, INT_PTR(0));
 213         release_function_indicator("free_irq");
 214
 215         return_implies_state("register_netdev", 0, 0, &request_granted, INT_PTR(0));
 216         return_implies_state("register_netdev", -MAX_ERRNO, -1, &request_denied, INT_PTR(0));
 217         add_function_hook("unregister_netdev", &match_release, INT_PTR(0));
 218         release_function_indicator("unregister_netdev");
 219
 220         return_implies_state("misc_register", 0, 0, &request_granted, INT_PTR(0));
 221         return_implies_state("misc_register", -MAX_ERRNO, -1, &request_denied, INT_PTR(0));
 222         add_function_hook("misc_deregister", &match_release, INT_PTR(0));
 223         release_function_indicator("misc_deregister");
 224
 225
 226         add_hook(&match_return, RETURN_HOOK);
 227 }