From 82a4218a06697ee5beaa6ba76704b0156b1a806c Mon Sep 17 00:00:00 2001
Message-Id: <82a4218a06697ee5beaa6ba76704b0156b1a806c@dist-git>
From: Jiri Denemark <jdenemar@redhat.com>
Date: Tue, 2 May 2017 18:56:06 +0200
Subject: [PATCH] qemu: Fix persistent migration of transient domains

While fixing a bug with incorrectly freed memory in commit
v3.1.0-399-g5498aa29a, I accidentally broke persistent migration of
transient domains. Before adding qemuDomainDefCopy in the path, the code
just took NULL from vm->newDef and used it as the persistent def, which
resulted in no persistent XML being sent in the migration cookie. This
scenario is perfectly valid and the destination correctly handles it by
using the incoming live definition and storing it as the persistent one.

After the mentioned commit libvirtd would just segfault in the described
scenario.

https://bugzilla.redhat.com/show_bug.cgi?id=1446205

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
(cherry picked from commit 59307fade86fb74db1f8f572433962233f7ac123)
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/qemu/qemu_migration.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index ac7e27319..5bf9bd10f 100644
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -3609,15 +3609,15 @@ qemuMigrationRun(virQEMUDriverPtr driver,
 
     if (flags & VIR_MIGRATE_PERSIST_DEST) {
         if (persist_xml) {
-            persistDef = qemuMigrationPrepareDef(driver, persist_xml,
-                                                 NULL, NULL);
-        } else {
-            persistDef = qemuDomainDefCopy(driver, vm->newDef,
-                                           VIR_DOMAIN_XML_SECURE |
-                                           VIR_DOMAIN_XML_MIGRATABLE);
+            if (!(persistDef = qemuMigrationPrepareDef(driver, persist_xml,
+                                                       NULL, NULL)))
+                goto cleanup;
+        } else if (vm->newDef) {
+            if (!(persistDef = qemuDomainDefCopy(driver, vm->newDef,
+                                                 VIR_DOMAIN_XML_SECURE |
+                                                 VIR_DOMAIN_XML_MIGRATABLE)))
+                goto cleanup;
         }
-        if (!persistDef)
-            goto cleanup;
     }
 
     mig = qemuMigrationEatCookie(driver, vm, cookiein, cookieinlen,
-- 
2.12.2