US-CERT Vulnerability Note VU#162289

[David Daney]

Tom Truscott wrote:
> Here is an unintended bug I encountered recently, hopefully the "cert" warning will catch this one too.
> 
>    int okay_to_increment (int i)
>    {
>       if (i + 1 < i)
>         return 0;  /* adding 1 would cause overflow */
>       return 1;    /* adding 1 is safe */
>    }
> 
> Any sort of bug can cause a security vulnerability, so I recommend that gcc developers work harder on warning messages.
> 

Do you want warnings on all logic errors in your code, or only those 
that could cause a security vulnerability?

The first case is easy, but I don't know of a simple algorithm that can 
distinguish the second :-).

David Daney