qemu: Don't crash when getting targets for a multipath

In one of my previous commits I've introduced code that creates
all devices for given (possible) multipath target. But I've made
a mistake there - the code accesses 'next->path' without checking
if the disk source is local. Note that the 'next->path' is
NULL/doesn't make sense for VIR_STORAGE_TYPE_NVME.

Fixes: a30078cb
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1814947Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/qemu/qemu_domain.c

@@ -15846,7 +15846,6 @@ qemuDomainNamespaceSetupDisk(virDomainObjPtr vm,
     bool hasNVMe = false;
 
     for (next = src; virStorageSourceIsBacking(next); next = next->backingStore) {
-        VIR_AUTOSTRINGLIST targetPaths = NULL;
         g_autofree char *tmpPath = NULL;
 
         if (next->type == VIR_STORAGE_TYPE_NVME) {
@@ -15855,6 +15854,8 @@ qemuDomainNamespaceSetupDisk(virDomainObjPtr vm,
             if (!(tmpPath = virPCIDeviceAddressGetIOMMUGroupDev(&next->nvme->pciAddr)))
                 return -1;
         } else {
+            VIR_AUTOSTRINGLIST targetPaths = NULL;
+
             if (virStorageSourceIsEmpty(next) ||
                 !virStorageSourceIsLocalStorage(next)) {
                 /* Not creating device. Just continue. */
@@ -15862,10 +15863,6 @@ qemuDomainNamespaceSetupDisk(virDomainObjPtr vm,
             }
 
             tmpPath = g_strdup(next->path);
-        }
-
-        if (virStringListAdd(&paths, tmpPath) < 0)
-            return -1;
 
             if (virDevMapperGetTargets(next->path, &targetPaths) < 0 &&
                 errno != ENOSYS && errno != EBADF) {
@@ -15879,6 +15876,10 @@ qemuDomainNamespaceSetupDisk(virDomainObjPtr vm,
                 return -1;
         }
 
+        if (virStringListAdd(&paths, tmpPath) < 0)
+            return -1;
+    }
+
     /* qemu-pr-helper might require access to /dev/mapper/control. */
     if (src->pr &&
         virStringListAdd(&paths, QEMU_DEVICE_MAPPER_CONTROL_PATH) < 0)