@safe and null dereferencing

[Steven Schveighoffer via Digitalmars-d]

On 7/27/17 3:50 PM, Moritz Maxeiner wrote:
> On Thursday, 27 July 2017 at 18:46:16 UTC, Jonathan M Davis wrote:
>> On Thursday, July 27, 2017 11:03:02 Steven Schveighoffer via 
>> Digitalmars-d wrote:
>>> A possibility:
>>>
>>> "@safe D does not support platforms or processes where dereferencing 
>>> a null pointer does not crash the program. In such situations, 
>>> dereferencing null is not defined, and @safe code will not prevent 
>>> this from happening."
>>>
>>> In terms of not marking C/C++ code safe, I am not convinced we need 
>>> to go that far, but it's not as horrible a prospect as having to 
>>> unmark D @safe code that might dereference null.
>>
>> I see no problem whatsoever requiring that the platform segfaults when 
>> you dereference null. Anything even vaguely modern will do that. 
>> Adding extra null checks is therefore redundant and complicates the 
>> compiler for no gain whatsoever.
> 
> Except that when someone gets (root) access to any modern Linux servers 
> running D services he now has an easy way to create a denial of service 
> attack the owner of the server won't easily be able to find the cause 
> of, because pretty much everything *looks* right, except that somehow 
> the D services hang.

Well, let's not forget that the services should not be dereferencing 
null. It's still a bug in the code.

It just may result in something other than a process exit.

I bet if you lowered that limit, you would cause all sorts of trouble, 
not just in D safe code. Imagine, any function that returns null 
specifically to mean an error, now may return it casually as the address 
of a valid item! You are going to screw up all checks for null!

-Steve