4.9-stable review patch. If anyone has any objections, please let me know.
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From: Joe Thornber ejt@redhat.com
commit 4561ffca88c546f96367f94b8f1e4715a9c62314 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/md/dm-cache-metadata.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/md/dm-cache-metadata.c +++ b/drivers/md/dm-cache-metadata.c @@ -1262,8 +1262,8 @@ static int __load_mappings(struct dm_cac 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; } } }