volser: range check acl header fields during dumps and restores

volser: range check acl header fields during dumps and restores

Perform range checks on the acl header fields when reading an
acl from a dump stream and when writing an acl to a dump
stream.

Before this change, a bogus value in the total, positive, or
negative acl fields from a dump stream could cause an out of
bounds access of the acl entries table, crashing the volume
server.

Reviewed-on: http://gerrit.openafs.org/11702
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 0bf9fba458b39035a09f45c1b63f1e65672d4c00)

Change-Id: Icebeb1d62900a7978f02177627a30e41de49a182
Reviewed-on: https://gerrit.openafs.org/12127
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Tested-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>