[RFC][PATCH] Disable CLONE_PARENT for init
oleg at redhat.com
Thu Jul 2 05:36:26 PDT 2009
On 07/02, Oleg Nesterov wrote:
> On 07/01, Sukadev Bhattiprolu wrote:
> > --- linux-mmotm.orig/kernel/fork.c 2009-06-30 23:01:06.000000000 -0700
> > +++ linux-mmotm/kernel/fork.c 2009-07-01 17:29:09.000000000 -0700
> > @@ -974,6 +974,16 @@ static struct task_struct *copy_process(
> > if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
> > return ERR_PTR(-EINVAL);
> > + /*
> > + * Siblings of global init remain as zombies on exit since they are
> > + * not reaped by their parent (swapper). To solve this and to avoid
> > + * multi-rooted process trees, prevent global and container-inits
> > + * from creating siblings.
> > + */
> > + if ((clone_flags & CLONE_PARENT) &&
> > + current->signal->flags & SIGNAL_UNKILLABLE)
> > + return ERR_PTR(-EINVAL);
> Acked-by: Oleg Nesterov <oleg at redhat.com>
Thinking more, perhaps it makes sense to disallow CLONE_VM too.
If init forks CLONE_VM task, this task can be killed by
sig_kernel_coredump signal. In that case init will be killed too
and the kernel will crash.
But this is minor, we can trust the global init.
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