On 09/20, Kees Cook wrote: > > On Wed, Sep 20, 2017 at 5:56 AM, Oleg Nesterov <[email protected]> wrote: > > @@ -908,13 +912,13 @@ long seccomp_get_filter(struct task_struct *task, > > unsigned long filter_off, > > if (!data) > > goto out; > > > > - get_seccomp_filter(task); > > + refcount_inc(&filter->usage); > > spin_unlock_irq(&task->sighand->siglock); > > > > if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog))) > > ret = -EFAULT; > > > > - put_seccomp_filter(task); > > + __put_seccomp_filter(filter); > > return ret; > > Given how reference counting is done for filters, I'd be happier with > leaving the get_seccomp_filter() as-is,
No, please note that filter != tsk->seccomp.filter, get_seccomp_filter() won't work. > (i.e. don't open-code > the refcount_inc()). agreed, probably another __get_seccomp_filter(filter) makes sense, especially if we do other changes like get_nth(). But imo not in this fix. Oleg.
