[lkml]   [2012]   [Feb]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [kernel-hardening] Re: Add overflow protection to kref
On Fri, Feb 17, 2012 at 09:54 -0800, Greg KH wrote:
> I'm referring to the fact that the use of kref in this type of error or
> problem is rare.
> Yes, we have these types of problems at times, but a kref doesn't seem
> to be involved in them that I know of, so changing the kref code
> wouldn't help here from what I can tell.

Ehr, what's the difference between kref and "raw" atomic_t in a refcounting case?
There is _no_ difference in sense of overflows as a kref uses the same atomic_t.

I second David that we should use kref for overflow protection: we want to
hook an overflow case somehow in cases atomic_t is used as a refcounter. It is
_ideally_ handled by introducing atomic_t's subtype. And this subtype already
exists - it is called kref.

I expect all atomic_t refcounters users have

if (atomic_dec_and_test()) smth_put()

pattern, otherwise it is not a true refcounter :) It should be straightforward to
move to kref.

Moving to atomic64_t is attractive, but:

1) we still should find all atomic_t refcounters. Why not move to kref then?

2) what to do with architectures-loosers?


Vasiliy Kulikov - bringing security into open computing environments

 \ /
  Last update: 2012-02-17 20:45    [W:0.056 / U:0.668 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site