check_freeing_devm.c

   1 /*
   2  * Copyright (C) 2013 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 #include "smatch.h"
  19
  20 STATE(devm);
  21
  22 static int my_id;
  23
  24 static void match_assign(const char *fn, struct expression *expr, void *unused)
  25 {
  26         set_state_expr(my_id, expr->left, &devm);
  27 }
  28
  29 static void match_allocation(struct expression *expr,
  30                              const char *name, struct symbol *sym,
  31                              struct allocation_info *info)
  32 {
  33         /*
  34          * Only handle devm_ memory allocator
  35          */
  36         if (strncmp(info->fn_name, "devm_", 5) == 0)
  37                 match_assign(name, expr, NULL);
  38 }
  39
  40 /*
  41  * This hook deals with things like:
  42  * ptr = devm_kmalloc(...);
  43  * if (!ptr)
  44  *      return -ENOMEM;
  45  * another_val = ptr;                   <==
  46  */
  47 static void match_reassign(struct expression *expr)
  48 {
  49         struct expression *left, *right;
  50
  51         if (expr->op != '=')
  52                 return;
  53
  54         right = strip_expr(expr->right);
  55         if (!get_state_expr(my_id, right))
  56                 return;
  57
  58         left = strip_expr(expr->left);
  59
  60         set_state_expr(my_id, left, &devm);
  61 }
  62
  63 static void match_free_func(const char *fn, struct expression *expr, void *_arg)
  64 {
  65         struct expression *arg_expr;
  66         int arg = PTR_INT(_arg);
  67         char *name;
  68
  69         arg_expr = get_argument_from_call_expr(expr->args, arg);
  70         if (!get_state_expr(my_id, arg_expr))
  71                 return;
  72         name = expr_to_str(arg_expr);
  73         sm_warning("passing devm_ allocated variable to %s. '%s'", fn, name);
  74         free_string(name);
  75 }
  76
  77 static void register_funcs_from_file(void)
  78 {
  79         struct token *token;
  80         const char *func;
  81         int arg;
  82
  83         token = get_tokens_file("kernel.frees_argument");
  84         if (!token)
  85                 return;
  86         if (token_type(token) != TOKEN_STREAMBEGIN)
  87                 return;
  88         token = token->next;
  89         while (token_type(token) != TOKEN_STREAMEND) {
  90                 if (token_type(token) != TOKEN_IDENT)
  91                         return;
  92                 func = show_ident(token->ident);
  93                 token = token->next;
  94                 if (token_type(token) != TOKEN_NUMBER)
  95                         return;
  96                 arg = atoi(token->number);
  97                 add_function_hook(func, &match_free_func, INT_PTR(arg));
  98                 token = token->next;
  99         }
 100         clear_token_alloc();
 101 }
 102
 103 void check_freeing_devm(int id)
 104 {
 105         if (option_project != PROJ_KERNEL)
 106                 return;
 107
 108         my_id = id;
 109
 110         /*
 111          * We register all allocation functions, but only devm_ will be handled
 112          * in match_allocation()
 113          */
 114         add_allocation_hook(&match_allocation);
 115
 116         add_function_assign_hook("devm_kstrdup", &match_assign, NULL);
 117         add_function_assign_hook("devm_kasprintf", &match_assign, NULL);
 118         add_function_assign_hook("devm_kvasprintf", &match_assign, NULL);
 119
 120         add_function_hook("kfree", &match_free_func, INT_PTR(0));
 121         add_function_hook("krealloc", &match_free_func, INT_PTR(0));
 122         register_funcs_from_file();
 123
 124         add_hook(&match_reassign, ASSIGNMENT_HOOK);
 125 }