commit 4561ffca88c546f96367f94b8f1e4715a9c62314
author Joe Thornber <ejt@redhat.com> Mon Sep 24 16:19:30 2018 -0400
committer Mike Snitzer <snitzer@redhat.com> Thu Oct 04 15:20:51 2018 -0400
tree 2143e12ead2aacd17d73d9ea90af991b13c5d032
parent 0328ba90407c82874f9f39f9a5a6e5ad6cb76f44

dm cache metadata: ignore hints array being too small during resize

Commit fd2fa9541 ("dm cache metadata: save in-core policy_hint_size to
on-disk superblock") enabled previously written policy hints to be
used after a cache is reactivated.  But in doing so the cache
metadata's hint array was left exposed to out of bounds access because
on resize the metadata's on-disk hint array wasn't ever extended.

Fix this by ignoring that there are no on-disk hints associated with the
newly added cache blocks.  An expanded on-disk hint array is later
rewritten upon the next clean shutdown of the cache.

Fixes: fd2fa9541 ("dm cache metadata: save in-core policy_hint_size to on-disk superblock")
Cc: stable@vger.kernel.org
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>