The following patch aims to fix a possible NULL-ptr-dereference that
occurs if a call to get_ep_from_tid() fails to assign nonzero
value.

Upstream commit 283861a4c52c1ea4df3dd1b6fc75a50796ce3524 has been
backported up to version 5.15. For some reason, older stable branches
have been ignored.

This backport can be cleanly applied to 4.19, 5.4 and 5.10 versions.

v2: Add stable maintainers as patch recepients.