Re: [PATCH] seccomp: Fix setting number of loaded filters

[Hsuan-Chi Kuo]

Thanks.

I was just trying to understand how seccomp works by code reading and 
spotted this bug.


On 8/11/21 1:46 PM, Kees Cook wrote:
> On Tue, Aug 10, 2021 at 02:51:58PM +0200, Wiktor Garbacz wrote:
> > The value is only reported through procfs so this
> > is purely cosmetic.
> Hi,
>
> Thanks for the patch! I thought this had already been fixed, but I see I
> dropped the ball. :( Sorry!
>
> I'll get the original fix landed[1], and add you as a reporter.
>
> Out of curiosity, how did you (or Hsuan-Chi Kuo) find this? Broken
> behavior, code reading, static analysis?
>
> Thanks!
>
> -Kees
>
> [1] https://lore.kernel.org/lkml/20210304233708.420597-1-hsuanchikuo@xxxxxxxxx/
>
> > Signed-off-by: Wiktor Garbacz <wiktorg@xxxxxxxxxx>
> > ---
> >   kernel/seccomp.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/kernel/seccomp.c b/kernel/seccomp.c
> > index 057e17f3215d..6469eca8078c 100644
> > --- a/kernel/seccomp.c
> > +++ b/kernel/seccomp.c
> > @@ -602,7 +602,7 @@ static inline void seccomp_sync_threads(unsigned long flags)
> >   		smp_store_release(&thread->seccomp.filter,
> >   				  caller->seccomp.filter);
> >   		atomic_set(&thread->seccomp.filter_count,
> > -			   atomic_read(&thread->seccomp.filter_count));
> > +			   atomic_read(&caller->seccomp.filter_count));
> >   
> >   		/*
> >   		 * Don't let an unprivileged task work around
> > --
> > 2.32.0.605.g8dce9f2422-goog