On Thu, Jul 09, 2020 at 10:00:42PM +0200, Jann Horn wrote:
> On Thu, Jul 9, 2020 at 8:26 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> > The sock counting (sock_update_netprioidx() and sock_update_classid())
> > was missing from pidfd's implementation of received fd installation. Add
> > a call to the new __receive_sock() helper.
> [...]
> > diff --git a/kernel/pid.c b/kernel/pid.c
> [...]
> > @@ -642,10 +643,12 @@ static int pidfd_getfd(struct pid *pid, int fd)
> > }
> >
> > ret = get_unused_fd_flags(O_CLOEXEC);
> > - if (ret < 0)
> > + if (ret < 0) {
> > fput(file);
> > - else
> > + } else {
> > fd_install(ret, file);
> > + __receive_sock(file);
> > + }
>
> __receive_sock() has to be before fd_install(), otherwise `file` can
> be a dangling pointer.
I've swapped the order now and double-checked the other uses. Everything
else seems fine.
--
Kees Cook
