check_kmalloc_wrong_size.c

   1 /*
   2  * Copyright (C) 2011 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 #include "smatch.h"
  19
  20 static int my_id;
  21
  22 static int get_data_size(struct expression *ptr)
  23 {
  24         struct symbol *type;
  25         int ret;
  26
  27         type = get_type(ptr);
  28         if (!type || type->type != SYM_PTR)
  29                 return 0;
  30         type = get_base_type(type);
  31         if (!type)
  32                 return 0;
  33         ret = bits_to_bytes(type->bit_size);
  34         if (ret == -1)
  35                 return 0;
  36         return ret;
  37 }
  38
  39 static void check_size_matches(int data_size, struct expression *size_expr)
  40 {
  41         sval_t sval;
  42
  43         if (data_size == 1)  /* this is generic a buffer */
  44                 return;
  45
  46         if (!get_implied_value(size_expr, &sval))
  47                 return;
  48         if (sval_cmp_val(sval, data_size) != 0)
  49                 sm_msg("warn: double check that we're allocating correct size: %d vs %s", data_size, sval_to_str(sval));
  50 }
  51
  52 static void match_alloc(const char *fn, struct expression *expr, void *unused)
  53 {
  54         struct expression *call = strip_expr(expr->right);
  55         struct expression *arg;
  56         int ptr_size;
  57
  58         ptr_size = get_data_size(expr->left);
  59         if (!ptr_size)
  60                 return;
  61
  62         arg = get_argument_from_call_expr(call->args, 0);
  63         arg = strip_expr(arg);
  64         if (!arg || arg->type != EXPR_BINOP || arg->op != '*')
  65                 return;
  66         if (expr->left->type == EXPR_SIZEOF)
  67                 check_size_matches(ptr_size, arg->left);
  68         if (expr->right->type == EXPR_SIZEOF)
  69                 check_size_matches(ptr_size, arg->right);
  70 }
  71
  72 static void match_calloc(const char *fn, struct expression *expr, void *_arg_nr)
  73 {
  74         int arg_nr = PTR_INT(_arg_nr);
  75         struct expression *call = strip_expr(expr->right);
  76         struct expression *arg;
  77         int ptr_size;
  78
  79         ptr_size = get_data_size(expr->left);
  80         if (!ptr_size)
  81                 return;
  82
  83         arg = get_argument_from_call_expr(call->args, arg_nr);
  84         check_size_matches(ptr_size, arg);
  85 }
  86
  87 void check_kmalloc_wrong_size(int id)
  88 {
  89         my_id = id;
  90
  91         if (option_project != PROJ_KERNEL) {
  92                 add_function_assign_hook("malloc", &match_alloc, NULL);
  93                 add_function_assign_hook("calloc", &match_calloc, INT_PTR(1));
  94                 return;
  95         }
  96
  97         add_function_assign_hook("kmalloc", &match_alloc, NULL);
  98         add_function_assign_hook("kcalloc", &match_calloc, INT_PTR(1));
  99 }