Re: [PATCH] selinux: replace BUG_ONs with WARN_ONs in avc.c

[Paul Moore <paul@paul-moore.com>]

On Mon, Jan 28, 2019 at 8:23 AM Stephen Smalley <sds@tycho.nsa.gov> wrote:
> On 1/26/19 5:18 AM, Ondrej Mosnacek wrote:
> > These checks are only guarding against programming errors that could
> > silently grant too many permissions. These cases are better handled with
> > WARN_ON(), since it doesn't really help much to crash the machine in
> > this case.
> >
> > Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
> > ---
> >   security/selinux/avc.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/security/selinux/avc.c b/security/selinux/avc.c
> > index 3a27418b20d7..84f108f4100a 100644
> > --- a/security/selinux/avc.c
> > +++ b/security/selinux/avc.c
> > @@ -1059,7 +1059,7 @@ int avc_has_extended_perms(struct selinux_state *state,
> >       int rc = 0, rc2;
> >
> >       xp_node = &local_xp_node;
> > -     BUG_ON(!requested);
> > +     WARN_ON(!requested);
>
> Should this be:
>         if (WARN_ON(!requested))
>                 return -EACCES;

I think so, it would be bad not to return an error in this case (and
the similar one below).

> >
> >       rcu_read_lock();
> >
> > @@ -1149,7 +1149,7 @@ inline int avc_has_perm_noaudit(struct selinux_state *state,
> >       int rc = 0;
> >       u32 denied;
> >
> > -     BUG_ON(!requested);
> > +     WARN_ON(!requested);
>
> And likewise
>
> >
> >       rcu_read_lock();
> >
> >

-- 
paul moore
www.paul-moore.com