mmap zero mapping disallowed (Re: svn commit: r197537 - head/sys/vm])

[Julian Elischer]

Robert Watson wrote:
> 
> On Sun, 27 Sep 2009, Simon L. Nielsen wrote:
> 
>> As mentioned in the commit message FreeBSD 9 / head now does not allow 
>> mmap'ing at zero by default, and this may break some apps.
>>
>> If anyone encounters applications which break because of this change, 
>> please let report it so we can see if it can be fixed.  It might not 
>> be possible to fix some applications, but we at least would know which 
>> applications might need a special note in the documentation.
> 
> There are probably some other ways to arrange mappings at 0x0, so we'll 
> need to dig through the system to identify them.  To mind, the various 
> executable image activators are interesting (elf, a.out, etc), but we 
> should check other things that call VM insertion routines -- things like 
> the more interesting 3D device drivers.  At the end of the day, this is 
> a mitigation technique, so if there are edge case non-default compiled 
> copmonents, etc, that's fine, but it would be nice to be thorough where 
> we can.
> 
> While our automatic address selection code ever pick 0x0 as a mapping 
> address, btw?
> 
> Robert N M Watson
> Computer Laboratory
> University of Cambridge
> 
> 
>>


What they need to do now is find a fault where the offset is > 4096..

I wouldn't bet against it..