ses: Fix problems with simple enclosures

ses: Fix problems with simple enclosures

commit 3417c1b5cb1fdc10261dbed42b05cc93166a78fd upstream.

Simple enclosure implementations (mostly USB) are allowed to return only
page 8 to every diagnostic query.  That really confuses our
implementation because we assume the return is the page we asked for and
end up doing incorrect offsets based on bogus information leading to
accesses outside of allocated ranges.  Fix that by checking the page
code of the return and giving an error if it isn't the one we asked for.
This should fix reported bugs with USB storage by simply refusing to
attach to enclosures that behave like this.  It's also good defensive
practise now that we're starting to see more USB enclosures.

Reported-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Tomas Henzl <thenzl@redhat.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>