[libvirt] [PATCH] snapshot: fix snapshot deletion

Eric Blake eblake at redhat.com
Tue Feb 14 20:48:48 UTC 2012


Bug introduced in commit 35abced.  On an inactive domain,
$ virsh snapshot-create-as dom snap
$ virsh snapshot-create dom
$ virsh snapshot-create dom
$ virsh snapshot-delete --children dom snap
could crash libvirtd, due to a use-after-free that results
when the callback freed the current element in the iteration.

* src/conf/domain_conf.c (virDomainSnapshotForEachChild)
(virDomainSnapshotActOnDescendant): Allow iteration to delete
current child.
---
 src/conf/domain_conf.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index f8d0a4c..da00830 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -13325,8 +13325,9 @@ virDomainSnapshotForEachChild(virDomainSnapshotObjPtr snapshot,
     virDomainSnapshotObjPtr child = snapshot->first_child;

     while (child) {
+        virDomainSnapshotObjPtr next = child->sibling;
         (iter)(child, child->def->name, data);
-        child = child->sibling;
+        child = next;
     }

     return snapshot->nchildren;
@@ -13346,10 +13347,10 @@ virDomainSnapshotActOnDescendant(void *payload,
     virDomainSnapshotObjPtr obj = payload;
     struct snapshot_act_on_descendant *curr = data;

-    (curr->iter)(payload, name, curr->data);
     curr->number += 1 + virDomainSnapshotForEachDescendant(obj,
                                                            curr->iter,
                                                            curr->data);
+    (curr->iter)(payload, name, curr->data);
 }

 /* Run iter(data) on all descendants of snapshot, while ignoring all
-- 
1.7.7.6




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