[Qemu-devel] [PATCH v6 10/17] qcow2/overlaps: Protect inactive L1 tables

[Max Reitz <mreitz@redhat.com>]

Keep track of the inactive L1 tables in the metadata list to protect
them against accidental modifications.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 block/qcow2-snapshot.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 6d1ae00..95afd87 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -122,6 +122,21 @@ int qcow2_read_snapshots(BlockDriverState *bs)
             ret = -EFBIG;
             goto fail;
         }
+
+        if (!(s->overlap_check & QCOW2_OL_INACTIVE_L1)) {
+            continue;
+        }
+
+        if (sn->l1_size > INT_MAX / sizeof(uint64_t)) {
+            /* Do not fail opening the image because a snapshot is broken which
+             * might not be used anyway */
+            continue;
+        }
+
+        qcow2_metadata_list_enter(bs, sn->l1_table_offset,
+                                  size_to_clusters(s, sn->l1_size *
+                                                      sizeof(uint64_t)),
+                                  QCOW2_OL_INACTIVE_L1);
     }
 
     assert(offset - s->snapshots_offset <= INT_MAX);
@@ -415,6 +430,11 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
     g_free(l1_table);
     l1_table = NULL;
 
+    qcow2_metadata_list_enter(bs, sn->l1_table_offset,
+                              size_to_clusters(s, sn->l1_size *
+                                                  sizeof(uint64_t)),
+                              QCOW2_OL_INACTIVE_L1);
+
     /*
      * Increase the refcounts of all clusters and make sure everything is
      * stable on disk before updating the snapshot table to contain a pointer
@@ -635,6 +655,11 @@ int qcow2_snapshot_delete(BlockDriverState *bs,
     g_free(sn.id_str);
     g_free(sn.name);
 
+    qcow2_metadata_list_remove(bs, sn.l1_table_offset,
+                               size_to_clusters(s, sn.l1_size *
+                                                   sizeof(uint64_t)),
+                               QCOW2_OL_INACTIVE_L1);
+
     /*
      * Now decrease the refcounts of clusters referenced by the snapshot and
      * free the L1 table.
-- 
2.4.6