Re: 8.0-RC1: kernel page fault in NLM master thread (VIMAGE or ZFS related?)

On Sun, 27 Sep 2009, Robert Watson wrote:

>
> On Fri, 25 Sep 2009, Jamie Gritton wrote:
>
>> It seems to be NFS related.  I think the null pointer in question is from 
>> the export's anonymous credential.  Try the patch below and see if it helps 
>> (which I guess means run it overnight and see if it crashes again).  I've 
>> also patched a similar missing cred prison in GSS_SVC, since I'm not versed 
>> enough in NFS/RPC stuff to know if it might be the problem.
>
> This is one of the reasons I really dislike "magic" credentials and special 
> handling of NULL credentials -- they always get into code the author doesn't 
> expect, and either there are bad pointer dereferences, or incorrect security 
> decisions.  It's almost always the case that a correct credential should have 
> been cached or generated at some earlier point to represent the security 
> context...
>
I don't really understand prisons/jails, but would creating these
credentials via:
 	crdup(td->td_ucred); // duplicating the daemon thread's cred
 	- and then replacing the <uid,gids>
make sense as an alternative to starting with crget()?
(ie. All the other stuff except <uid,gids> would be "inherited" from the
credential for the daemon thread.)

rick