Difference between revisions of "Strings and Integers"

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#Off-by-one errors`
 
#Off-by-one errors`
  
Some of the issues mentioned above have been covered in the "Reviewing code buffer overflows and overruns" section previously in this guide.
+
Some of the issues mentioned above have been covered in the "Reviewing Code for Buffer Overruns and Overflows" section previously in this guide.
 +
 
 +
===Unbounded Errors===
 +
====String Copies====
 +
 
 +
Occur when data is copied from a unbounded source to a fixed length character array
 +
 
 +
void main(void) {
 +
  char Name[10];
 +
  puts("Enter your name:");
 +
  gets(Name); <-- Here the name input by the user can be of arbitary length over running the Name array.
 +
...
 +
  }

Revision as of 13:06, 6 November 2007

Strings are not a defined Type in C or C++ but simply a contigous array of characters terminated by a null (\0) character The length of the string is the amount of characters which preseed the null character. C++ does contain template classes which address this feature of the programming language: std::basic_string and std::string These classes address some security issues but not all.

|W|E|L|C|O|M|E|\0|


Common String Errors

Common string errors can be related to mistakes in implementation which may cause drastic security and availability issues. C/C++ do not have the comfort other programming languages provide such as Java and C# .NET relating to buffer overflows and such due to a String Type not being defined.

Common issues include:

  1. Input validation errors
  2. Unbounded Errors
  3. Truncation issues
  4. Out-of-bounds writes
  5. String Termination Errors
  6. Off-by-one errors`

Some of the issues mentioned above have been covered in the "Reviewing Code for Buffer Overruns and Overflows" section previously in this guide.

Unbounded Errors

String Copies

Occur when data is copied from a unbounded source to a fixed length character array

void main(void) {
 char Name[10];
 puts("Enter your name:");
 gets(Name); <-- Here the name input by the user can be of arbitary length over running the Name array.
...
 }