On Fri, Sep 28, 2018 at 10:33:34PM +0200, Jann Horn wrote: > On Fri, Sep 28, 2018 at 5:47 PM Tycho Andersen <ty...@tycho.ws> wrote: > > As Jann pointed out, there is a race between SECCOMP_FILTER_FLAG_TSYNC and > > the ptrace code that can inspect a filter of another process. Let's > > introduce read locking into the two ptrace accesses so that we don't race. > > Hmm. Is that true? The ptrace code uses get_nth_filter(), which holds > the siglock while grabbing the seccomp filter and bumping its > refcount. And TSYNC happens from seccomp_set_mode_filter(), which > takes the siglock. So this looks okay to me?
Oh, yes, you're right. So I guess we should just change the comment to say we're using siglock to represent the read lock. Tycho
