Spec#, nullables and more

[Daniel Gibson]

Walter Bright schrieb:
> bearophile wrote:
>> Walter Bright:
>>
>>> The $10 billion mistake was C's conversion of arrays to pointers when
>>> passing to a function.
>>>
>>> http://www.drdobbs.com/blog/archives/2009/12/cs_biggest_mist.html
>>>
>>> Sadly, there's an ongoing failure to recognize this, as it is never
>>> addressed in any of the revisions to the C or C++ standards,
>>
>> I agree, that's a very bad problem, probably worse than null-related 
>> bugs.
> 
> It's infinitely worse. Null pointers do not result in memory corruption, 
> buffer overflows, and security breaches.
> 

Not entirely true: Null Pointer dereferences *have* been used for security breaches, see for 
example: http://lwn.net/Articles/342330/
The problem is that one can mmap() to 0/NULL so it can be dereferenced without causing a crash.

Of course this is also a problem of the OS, it shouldn't allow mmap()ing to NULL in the first place 
(it's now forbidden by default on Linux and FreeBSD afaik) - but some software (dosemu, wine) 
doesn't work without it.

Cheers,
- Daniel