From: Masayoshi Mizuma <m.mizuma(a)jp.fujitsu.com&gt; When <transient shareBacking='yes'> is set to a disk and the overlay disk already exists because of something abnormal, libvirt is terminated by Segmentation fault. # virsh start Test0 error: Disconnected from qemu:///system due to end of file error: Failed to start domain 'Test0' error: End of file while reading data: Input/output error Add NULL check for snapdiskdef so that the rollback can work correctly. Signed-off-by: Masayoshi Mizuma <m.mizuma(a)jp.fujitsu.com&gt; --- src/qemu/qemu_hotplug.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c index 9ff6175dd3..0640cdd9f7 100644 --- a/src/qemu/qemu_hotplug.c +++ b/src/qemu/qemu_hotplug.c @@ -695,7 +695,9 @@ qemuDomainAttachDiskGenericTransient(virDomainObj *vm, g_autoptr(qemuSnapshotDiskContext) snapctxt = NULL; g_autoptr(virDomainSnapshotDiskDef) snapdiskdef = NULL; - snapdiskdef = qemuSnapshotGetTransientDiskDef(disk, vm->def->name); + if (!(snapdiskdef = qemuSnapshotGetTransientDiskDef(disk, vm->def->name))) + return NULL; + snapctxt = qemuSnapshotDiskContextNew(1, vm, asyncJob); if (qemuSnapshotDiskPrepareOne(snapctxt, disk, snapdiskdef, -- 2.27.0