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>

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 69dddeab124c2e1ac075dc24c14ebe725647e3a3..5936de71883fb7f637b0192bf3144910d6e193d5 100644 (file)
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -1455,8 +1455,8 @@ static int __load_mappings(struct dm_cache_metadata *cmd,
                if (hints_valid) {
                        r = dm_array_cursor_next(&cmd->hint_cursor);
                        if (r) {
-                               DMERR("dm_array_cursor_next for hint failed");
-                               goto out;
+                               dm_array_cursor_end(&cmd->hint_cursor);
+                               hints_valid = false;
                        }
                }