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

jthornber · snitm · commit 4561ffca88c5 · 2018-10-04T15:20:51.000-04:00
Commit fd2fa95 ("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: fd2fa95 ("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
@@ -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;
 			}
 		}
 

Original file line number	Diff line number	Diff line change
`@@ -1455,8 +1455,8 @@ static int __load_mappings(struct dm_cache_metadata *cmd,`
`1455`	`1455`	`if (hints_valid) {`
`1456`	`1456`	`r = dm_array_cursor_next(&cmd->hint_cursor);`
`1457`	`1457`	`if (r) {`
`1458`		`- DMERR("dm_array_cursor_next for hint failed");`
`1459`		`- goto out;`
	`1458`	`+ dm_array_cursor_end(&cmd->hint_cursor);`
	`1459`	`+ hints_valid = false;`
`1460`	`1460`	`}`
`1461`	`1461`	`}`
`1462`	`1462`