[kernel-hardening] Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/ directory v6

[Cyrill Gorcunov <gorcunov@gmail.com>]

On Thu, Sep 08, 2011 at 04:52:01PM -0700, Andrew Morton wrote:
> On Thu, 8 Sep 2011 10:04:05 +0400
> Cyrill Gorcunov <gorcunov@gmail.com> wrote:
> 
> > fs, proc: Introduce the /proc/<pid>/map_files/ directory v11
> 
> Ho hum, I've pretty much run out of excuses to avoid merging this.
> 
> except...
> 
> We don't really want to bloat fs/proc/base.o by 4k until all the other
> things which support c/r are mergeable and we know that the whole
> project is actually useful.  When will we be at this stage?

I hope we will bring in a final set in a couple of weeks.

> 
> <looks at the warning>
> 
> fs/proc/base.c: In function 'proc_map_files_instantiate':
> fs/proc/base.c:2348: warning: assignment from incompatible pointer type
> 
> err, that code will crash at runtime and it isn't trivial to fix. 
> How could this happen?
> 

Hmm. I never saw this warning. (Andrew, I'm still unable to fetch
your current -mm tree, is there some place other than kernel.org?
So the patch is done on top of 3.1-rc3). I guess this warrning is
from p = flex_array_get(fa, i); ? (since I don't have any warning
at all).

> >
> > ...
> >
> > +				if (fa)
> > +					flex_array_free(fa);
> >
> > ...
> >
> > +		if (fa)
> > +			flex_array_free(fa);
> 
> I think I'll do this:
> 
> From: Andrew Morton <akpm@linux-foundation.org>
> 
> Lots of callers are avoiding passing NULL into flex_array_free().  Move
> the check into flex_array_free() in the usual fashion.
> 
> Cc: Stephen Smalley <sds@tycho.nsa.gov>
> Cc: James Morris <jmorris@namei.org>
> Cc: Cyrill Gorcunov <gorcunov@gmail.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---

Yeah, great. Moreover, flex_array_free calls for kfree which
support NULL argument so it's natural to make this one NULL
capable as well.

	Cyrill