virDomainDiskSourceFormatInternal: Avoid leaking @childBuf

If formatting of storage encryption or private data fails we must
jump to the error label instead of returning immediately
otherwise @attrBuf and @childBuf might be leaked.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>

src/conf/domain_conf.c

@@ -22911,10 +22911,10 @@ virDomainDiskSourceFormatInternal(virBufferPtr buf,
          * as we found it. */
         if (src->encryption && src->encryptionInherited &&
             virStorageEncryptionFormat(&childBuf, src->encryption) < 0)
-            return -1;
+            goto error;
 
         if (virDomainDiskSourceFormatPrivateData(&childBuf, src, flags, xmlopt) < 0)
-            return -1;
+            goto error;
 
         if (virXMLFormatElement(buf, "source", &attrBuf, &childBuf) < 0)
             goto error;