[libvirt] [PATCH] Add several missing vir*Free calls in libvirtd's remote code

[Matthias Bolte]

Justin Clift reported a problem with adding virStoragePoolIsPersistent
to virsh's pool-info command, resulting in a strange problem. Here's
an example:

    virsh # pool-create-as images_dir3 dir - - - - "/home/images2"
    Pool images_dir3 created

    virsh # pool-info images_dir3
    Name:           images_dir3
    UUID:           90301885-94eb-4ca7-14c2-f30b25a29a36
    State:          running
    Capacity:       395.20 GB
    Allocation:     30.88 GB
    Available:      364.33 GB

    virsh # pool-destroy images_dir3
    Pool images_dir3 destroyed

At this point the images_dir3 pool should be gone (because it was
transient) and we should be able to create a new pool with the same name:

    virsh # pool-create-as images_dir3 dir - - - - "/home/images2"
    Pool images_dir3 created

    virsh # pool-info images_dir3
    Name:           images_dir3
    UUID:           90301885-94eb-4ca7-14c2-f30b25a29a36
    error: Storage pool not found

The new pool got the same UUID as the first one, but we didn't specify
one. libvirt should have picked a random UUID, but it didn't.

It turned out that virStoragePoolIsPersistent leaks a reference to the
storage pool object (actually remoteDispatchStoragePoolIsPersistent does).
As a result, pool-destroy doesn't remove the virStoragePool for the
"images_dir3" pool from the virConnectPtr's storagePools hash on libvirtd's
side. Then the second pool-create-as get's the stale virStoragePool object
associated with the "images_dir3" name. But this object has the old UUID.

This commit ensures that all get_nonnull_* and make_nonnull_* calls for
libvirt objects are matched properly with vir*Free calls. This fixes the
reference leaks and the reported problem.

All remoteDispatch*IsActive and remoteDispatch*IsPersistent functions were
affected. But also remoteDispatchDomainMigrateFinish2 was affected in the
success path. I wonder why that didn't surface earlier. Probably because
domainMigrateFinish2 is executed on the destination host and in the common
case this connection is opened especially for the migration and gets closed
after the migration is done. So there was no chance to run into a problem
because of the leaked reference.
---
 daemon/remote.c |   18 +++++++++++++++++-
 1 files changed, 17 insertions(+), 1 deletions(-)

diff --git a/daemon/remote.c b/daemon/remote.c
index c54565c..1fa0f24 100644
--- a/daemon/remote.c
+++ b/daemon/remote.c
@@ -979,9 +979,10 @@ remoteDispatchDomainMemoryStats (struct qemud_server *server ATTRIBUTE_UNUSED,
 
     /* Allocate stats array for making dispatch call */
     if (VIR_ALLOC_N(stats, args->maxStats) < 0) {
+        virDomainFree (dom);
         remoteDispatchOOMError(rerr);
         return -1;
-     }
+    }
 
     nr_stats = virDomainMemoryStats (dom, stats, args->maxStats, 0);
     virDomainFree (dom);
@@ -1885,6 +1886,7 @@ remoteDispatchDomainMigrateFinish2 (struct qemud_server *server ATTRIBUTE_UNUSED
     }
 
     make_nonnull_domain (&ret->ddom, ddom);
+    virDomainFree (ddom);
 
     return 0;
 }
@@ -5570,10 +5572,12 @@ static int remoteDispatchDomainIsActive(struct qemud_server *server ATTRIBUTE_UN
     ret->active = virDomainIsActive(domain);
 
     if (ret->active < 0) {
+        virDomainFree(domain);
         remoteDispatchConnError(err, conn);
         return -1;
     }
 
+    virDomainFree(domain);
     return 0;
 }
 
@@ -5596,10 +5600,12 @@ static int remoteDispatchDomainIsPersistent(struct qemud_server *server ATTRIBUT
     ret->persistent = virDomainIsPersistent(domain);
 
     if (ret->persistent < 0) {
+        virDomainFree(domain);
         remoteDispatchConnError(err, conn);
         return -1;
     }
 
+    virDomainFree(domain);
     return 0;
 }
 
@@ -5622,10 +5628,12 @@ static int remoteDispatchInterfaceIsActive(struct qemud_server *server ATTRIBUTE
     ret->active = virInterfaceIsActive(iface);
 
     if (ret->active < 0) {
+        virInterfaceFree(iface);
         remoteDispatchConnError(err, conn);
         return -1;
     }
 
+    virInterfaceFree(iface);
     return 0;
 }
 
@@ -5648,10 +5656,12 @@ static int remoteDispatchNetworkIsActive(struct qemud_server *server ATTRIBUTE_U
     ret->active = virNetworkIsActive(network);
 
     if (ret->active < 0) {
+        virNetworkFree(network);
         remoteDispatchConnError(err, conn);
         return -1;
     }
 
+    virNetworkFree(network);
     return 0;
 }
 
@@ -5674,10 +5684,12 @@ static int remoteDispatchNetworkIsPersistent(struct qemud_server *server ATTRIBU
     ret->persistent = virNetworkIsPersistent(network);
 
     if (ret->persistent < 0) {
+        virNetworkFree(network);
         remoteDispatchConnError(err, conn);
         return -1;
     }
 
+    virNetworkFree(network);
     return 0;
 }
 
@@ -5700,10 +5712,12 @@ static int remoteDispatchStoragePoolIsActive(struct qemud_server *server ATTRIBU
     ret->active = virStoragePoolIsActive(pool);
 
     if (ret->active < 0) {
+        virStoragePoolFree(pool);
         remoteDispatchConnError(err, conn);
         return -1;
     }
 
+    virStoragePoolFree(pool);
     return 0;
 }
 
@@ -5726,10 +5740,12 @@ static int remoteDispatchStoragePoolIsPersistent(struct qemud_server *server ATT
     ret->persistent = virStoragePoolIsPersistent(pool);
 
     if (ret->persistent < 0) {
+        virStoragePoolFree(pool);
         remoteDispatchConnError(err, conn);
         return -1;
     }
 
+    virStoragePoolFree(pool);
     return 0;
 }
 
-- 
1.7.0.4