dm vdo: return error on corrupted metadata in start_restoring_volume functions

The return values of VDO_ASSERT calls that validate metadata are not acted
upon.

Return UDS_CORRUPT_DATA in case of an error.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: a4eb7e2 ("dm vdo: implement the volume index")
Signed-off-by: Ivan Abramov <[email protected]>
Reviewed-by: Matthew Sakai <[email protected]>
Signed-off-by: Mikulas Patocka <[email protected]>

Author: Ivan Abramov

drivers/md/dm-vdo/indexer/volume-index.c

@@ -836,7 +836,7 @@ static int start_restoring_volume_sub_index(struct volume_sub_index *sub_index,
 				    "%zu bytes decoded of %zu expected", offset,
 				    sizeof(buffer));
 		if (result != VDO_SUCCESS)
-			result = UDS_CORRUPT_DATA;
+			return UDS_CORRUPT_DATA;
 
 		if (memcmp(header.magic, MAGIC_START_5, MAGIC_SIZE) != 0) {
 			return vdo_log_warning_strerror(UDS_CORRUPT_DATA,
@@ -928,7 +928,7 @@ static int start_restoring_volume_index(struct volume_index *volume_index,
 				    "%zu bytes decoded of %zu expected", offset,
 				    sizeof(buffer));
 		if (result != VDO_SUCCESS)
-			result = UDS_CORRUPT_DATA;
+			return UDS_CORRUPT_DATA;
 
 		if (memcmp(header.magic, MAGIC_START_6, MAGIC_SIZE) != 0)
 			return vdo_log_warning_strerror(UDS_CORRUPT_DATA,