Description: ovl: Copy-up from nosuid lower to suid upper could allow priv-esc
References:
 https://bugzilla.redhat.com/show_bug.cgi?id=2009704
 https://www.openwall.com/lists/oss-security/2021/10/14/3
 https://www.openwall.com/lists/oss-security/2021/10/20/1
Notes:
 bwh> Only likely to be exploitable after commit 459c7c565ac3
 bwh> "ovl: unprivieged mounts" in 5.11-rc1, or if the
 bwh> Debian-specific module parameter permit_mounts_in_userns
 bwh> is enabled.
 carnil> According to the followups, is considered a misconfiguration of
 carnil> the mount, and not a kernel bug. Should we retire the CVE?
Bugs:
upstream: needed
6.1-upstream-stable: needed
5.10-upstream-stable: needed
4.19-upstream-stable: needed
4.9-upstream-stable: ignored "EOL"
sid: needed
6.1-bookworm-security: needed
5.10-bullseye-security: needed
4.19-buster-security: needed
4.9-stretch-security: ignored "EOL"