check_kmalloc_wrong_size.c

   1 /*
   2  * smatch/check_kmalloc_wrong_size.c
   3  *
   4  * Copyright (C) 2011 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11
  12 static int my_id;
  13
  14 static int get_data_size(struct expression *ptr)
  15 {
  16         struct symbol *type;
  17         int ret;
  18
  19         type = get_type(ptr);
  20         if (!type || type->type != SYM_PTR)
  21                 return 0;
  22         type = get_base_type(type);
  23         if (!type)
  24                 return 0;
  25         ret = bits_to_bytes(type->bit_size);
  26         if (ret == -1)
  27                 return 0;
  28         return ret;
  29 }
  30
  31 static void check_size_matches(int data_size, struct expression *size_expr)
  32 {
  33         sval_t sval;
  34
  35         if (data_size == 1)  /* this is generic a buffer */
  36                 return;
  37
  38         if (!get_implied_value_sval(size_expr, &sval))
  39                 return;
  40         if (sval_cmp_val(sval, data_size) != 0)
  41                 sm_msg("warn: double check that we're allocating correct size: %d vs %s", data_size, sval_to_str(sval));
  42 }
  43
  44 static void match_alloc(const char *fn, struct expression *expr, void *unused)
  45 {
  46         struct expression *call = strip_expr(expr->right);
  47         struct expression *arg;
  48         int ptr_size;
  49
  50         ptr_size = get_data_size(expr->left);
  51         if (!ptr_size)
  52                 return;
  53
  54         arg = get_argument_from_call_expr(call->args, 0);
  55         arg = strip_expr(arg);
  56         if (!arg || arg->type != EXPR_BINOP || arg->op != '*')
  57                 return;
  58         if (expr->left->type == EXPR_SIZEOF)
  59                 check_size_matches(ptr_size, arg->left);
  60         if (expr->right->type == EXPR_SIZEOF)
  61                 check_size_matches(ptr_size, arg->right);
  62 }
  63
  64 static void match_calloc(const char *fn, struct expression *expr, void *_arg_nr)
  65 {
  66         int arg_nr = PTR_INT(_arg_nr);
  67         struct expression *call = strip_expr(expr->right);
  68         struct expression *arg;
  69         int ptr_size;
  70
  71         ptr_size = get_data_size(expr->left);
  72         if (!ptr_size)
  73                 return;
  74
  75         arg = get_argument_from_call_expr(call->args, arg_nr);
  76         check_size_matches(ptr_size, arg);
  77 }
  78
  79 void check_kmalloc_wrong_size(int id)
  80 {
  81         my_id = id;
  82
  83         if (option_project != PROJ_KERNEL) {
  84                 add_function_assign_hook("malloc", &match_alloc, NULL);
  85                 add_function_assign_hook("calloc", &match_calloc, INT_PTR(1));
  86                 return;
  87         }
  88
  89         add_function_assign_hook("kmalloc", &match_alloc, NULL);
  90         add_function_assign_hook("kcalloc", &match_calloc, INT_PTR(1));
  91 }