[PATCH 1/2] dm vdo indexer: prevent delta list overflow on load

Check for corrupted delta lists sizes that overflow the
memory available for the delta_lists. An overflow can
cause the delta list data to be written outside the
reserved delta memory space.

Signed-off-by: Matthew Sakai <[email protected]>
---
 drivers/md/dm-vdo/indexer/delta-index.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/md/dm-vdo/indexer/delta-index.c b/drivers/md/dm-vdo/indexer/delta-index.c
index b288749067de..257612b81a9d 100644
--- a/drivers/md/dm-vdo/indexer/delta-index.c
+++ b/drivers/md/dm-vdo/indexer/delta-index.c
@@ -800,7 +800,7 @@ static void compute_new_list_offsets(struct delta_zone *delta_zone, u32 growing_
 		(delta_zone->size * BITS_PER_BYTE - delta_lists[tail_guard_index].size);
 }
 
-static void rebalance_lists(struct delta_zone *delta_zone)
+static int rebalance_lists(struct delta_zone *delta_zone)
 {
 	struct delta_list *delta_lists;
 	u32 i;
@@ -811,9 +811,17 @@ static void rebalance_lists(struct delta_zone *delta_zone)
 	for (i = 0; i <= delta_zone->list_count + 1; i++)
 		used_space += get_delta_list_byte_size(&delta_lists[i]);
 
+	if (delta_zone->size < used_space) {
+		return vdo_log_warning_strerror(UDS_CORRUPT_DATA,
+						"delta zone lists overflow zone size %zu",
+						delta_zone->size);
+	}
+
 	compute_new_list_offsets(delta_zone, 0, 0, used_space);
 	for (i = 1; i <= delta_zone->list_count + 1; i++)
 		delta_lists[i].start = delta_zone->new_offsets[i];
+
+	return UDS_SUCCESS;
 }
 
 /* Start restoring a delta index from multiple input streams. */
@@ -941,8 +949,11 @@ int uds_start_restoring_delta_index(struct delta_index *delta_index,
 	}
 
 	/* Prepare each zone to start receiving the delta list data. */
-	for (z = 0; z < delta_index->zone_count; z++)
-		rebalance_lists(&delta_index->delta_zones[z]);
+	for (z = 0; z < delta_index->zone_count; z++) {
+		result = rebalance_lists(&delta_index->delta_zones[z]);
+		if (result != UDS_SUCCESS)
+			return result;
+	}
 
 	return UDS_SUCCESS;
 }
-- 
2.53.0