NFS mounts failing when keytab present on client

[Michael Young]

NFS mounts stopped working on one of my computers after a kernel update 
from 4.15.3 to 4.15.4. I traced the problem to the commit
[46e8d06e423c4f35eac7a8b677b713b3ec9b0684] crypto: hash - prevent using 
keyed hashes without setting key
and a later kernel with this patch reverted works normally.

The problem seems to be related to kerberos as the mount fails when the 
keytab is present, but works if I rename the keytab file. This is true 
even though the mount is with sec=sys . The mount should also work with 
sec=krb5 but that also fails in the same way. When the mount fails there 
are errors in dmesg like
[ 1232.522816] gss_marshal: gss_get_mic FAILED (851968)
[ 1232.522819] RPC: couldn't encode RPC header, exit EIO
[ 1232.522856] gss_marshal: gss_get_mic FAILED (851968)
[ 1232.522857] RPC: couldn't encode RPC header, exit EIO
[ 1232.522863] NFS: nfs4_discover_server_trunking unhandled error -5. 
Exiting with error EIO
[ 1232.525039] gss_marshal: gss_get_mic FAILED (851968)
[ 1232.525042] RPC: couldn't encode RPC header, exit EIO

	Michael Young