kernel is vulnerable to denial of service (DoS). The vulnerability exists through a NULL pointer dereference in lookup_slow function.
access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/7.7_release_notes/index
access.redhat.com/errata/RHSA-2019:2029
access.redhat.com/errata/RHSA-2019:2043
access.redhat.com/security/updates/classification/#important
bugzilla.kernel.org/show_bug.cgi?id=199367
bugzilla.redhat.com/show_bug.cgi?id=1335986
bugzilla.redhat.com/show_bug.cgi?id=1436351
bugzilla.redhat.com/show_bug.cgi?id=1537033
bugzilla.redhat.com/show_bug.cgi?id=1552203
bugzilla.redhat.com/show_bug.cgi?id=1577640
bugzilla.redhat.com/show_bug.cgi?id=1590228
bugzilla.redhat.com/show_bug.cgi?id=1593417
bugzilla.redhat.com/show_bug.cgi?id=1608955
bugzilla.redhat.com/show_bug.cgi?id=1609699
bugzilla.redhat.com/show_bug.cgi?id=1613056
bugzilla.redhat.com/show_bug.cgi?id=1616109
bugzilla.redhat.com/show_bug.cgi?id=1616425
bugzilla.redhat.com/show_bug.cgi?id=1622167
bugzilla.redhat.com/show_bug.cgi?id=1627563
bugzilla.redhat.com/show_bug.cgi?id=1628378
bugzilla.redhat.com/show_bug.cgi?id=1659146
bugzilla.redhat.com/show_bug.cgi?id=1665990
bugzilla.redhat.com/show_bug.cgi?id=1684780
bugzilla.redhat.com/show_bug.cgi?id=1693457
git.kernel.org/pub/scm/fs/xfs/xfs-linux.git/commit/?h=for-next&id=afca6c5b2595fc44383919fba740c194b0b76aff
github.com/torvalds/linux/commit/afca6c5b2595fc44383919fba740c194b0b76aff
usn.ubuntu.com/4094-1/