check_cast_assign.c

   1 /*
   2  * smatch/check_cast_assign.c
   3  *
   4  * Copyright (C) 2012 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11 #include "smatch_extra.h"
  12 #include "smatch_slist.h"
  13
  14 static int my_id;
  15
  16 static struct symbol *get_cast_type(struct expression *expr)
  17 {
  18         if (!expr || expr->type != EXPR_PREOP || expr->op != '*')
  19                 return NULL;
  20         expr = strip_parens(expr->unop);
  21         if (expr->type != EXPR_CAST)
  22                 return NULL;
  23         return get_pointer_type(expr);
  24 }
  25
  26 static void match_overflow(struct expression *expr)
  27 {
  28         struct expression *ptr;
  29         struct symbol *type;
  30         int cast_size;
  31         int data_size;
  32
  33         type = get_cast_type(expr->left);
  34         if (!type)
  35                 return;
  36         cast_size = bits_to_bytes(type->bit_size);
  37
  38         ptr = strip_expr(expr->left->unop);
  39         data_size = get_array_size_bytes_min(ptr);
  40         if (data_size <= 0)
  41                 return;
  42         if (data_size >= cast_size)
  43                 return;
  44         sm_msg("warn: potential memory corrupting cast %d vs %d bytes",
  45                cast_size, data_size);
  46 }
  47
  48 void check_cast_assign(int id)
  49 {
  50         my_id = id;
  51         add_hook(&match_overflow, ASSIGNMENT_HOOK);
  52 }
  53