phonet/pep: refuse to enable an unbound pipe

stable inclusion
from stable-v4.19.222
commit 982b6ba1ce626ef87e5c29f26f2401897554f235
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I95RE9
CVE: CVE-2021-47086

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=982b6ba1ce626ef87e5c29f26f2401897554f235



--------------------------------

commit 75a2f315 upstream.

This ioctl() implicitly assumed that the socket was already bound to
a valid local socket name, i.e. Phonet object. If the socket was not
bound, two separate problems would occur:

1) We'd send an pipe enablement request with an invalid source object.
2) Later socket calls could BUG on the socket unexpectedly being
   connected yet not bound to a valid object.

Reported-by:  <syzbot+2dc91e7fc3dea88b1e8a@syzkaller.appspotmail.com>
Signed-off-by: Rémi Denis-Courmont <remi@remlab.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com>