lkml.org 
[lkml]   [2014]   [Jul]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v9 09/11] seccomp: introduce writer locking
On 07/09, Oleg Nesterov wrote:
>
> On 06/27, Kees Cook wrote:
> >
> > static u32 seccomp_run_filters(int syscall)
> > {
> > - struct seccomp_filter *f;
> > + struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
>
> I am not sure...
>
> This is fine if this ->filter is the 1st (and only) one, in this case
> we can rely on rmb() in the caller.
>
> But the new filter can be installed at any moment. Say, right after that
> rmb() although this doesn't matter. Either we need smp_read_barrier_depends()
> after that, or smp_load_acquire() like the previous version did?

Wait... and it seems that seccomp_sync_threads() needs smp_store_release()
when it sets thread->filter = current->filter by the same reason?

OTOH. smp_store_release() in seccomp_attach_filter() can die, "current"
doesn't need a barrier to serialize with itself.

Oleg.



\
 
 \ /
  Last update: 2014-07-09 21:41    [W:0.441 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site