nwfilter: Fix potential locking problems on ObjLoad failure

In virNWFilterObjLoad we can still fail after virNWFilterObjAssignDef,
but we don't unlock and free the created virNWFilterObjPtr in the
cleanup path.

The bit we are trying to do after AssignDef is just STRDUP in the
configFile path. However caching the configFile in the NWFilterObj
is largely redundant and doesn't follow the same pattern we use
for domain and network objects.

So just remove all the configFile caching which fixes the latent
bug as a side effect.

src/conf/nwfilter_conf.c

@@ -353,8 +353,6 @@ virNWFilterObjFree(virNWFilterObjPtr obj)
     virNWFilterDefFree(obj->def);
     virNWFilterDefFree(obj->newDef);
 
-    VIR_FREE(obj->configFile);
-
     virMutexDestroy(&obj->lock);
 
     VIR_FREE(obj);
@@ -3181,12 +3179,6 @@ virNWFilterObjLoad(virNWFilterObjListPtr nwfilters,
         return NULL;
     }
 
-    VIR_FREE(nwfilter->configFile); /* for driver reload */
-    if (VIR_STRDUP(nwfilter->configFile, path) < 0) {
-        virNWFilterDefFree(def);
-        return NULL;
-    }
-
     return nwfilter;
 }
 
@@ -3234,60 +3226,66 @@ virNWFilterLoadAllConfigs(virNWFilterObjListPtr nwfilters,
 
 int
 virNWFilterObjSaveDef(virNWFilterDriverStatePtr driver,
-                      virNWFilterObjPtr nwfilter,
                       virNWFilterDefPtr def)
 {
     char uuidstr[VIR_UUID_STRING_BUFLEN];
     char *xml;
-    int ret;
-
-    if (!nwfilter->configFile) {
-        if (virFileMakePath(driver->configDir) < 0) {
-            virReportSystemError(errno,
-                                 _("cannot create config directory %s"),
-                                 driver->configDir);
-            return -1;
-        }
+    int ret = -1;
+    char *configFile = NULL;
 
-        if (!(nwfilter->configFile = virFileBuildPath(driver->configDir,
-                                                      def->name, ".xml"))) {
-            return -1;
-        }
+    if (virFileMakePath(driver->configDir) < 0) {
+        virReportSystemError(errno,
+                             _("cannot create config directory %s"),
+                             driver->configDir);
+        goto error;
+    }
+
+    if (!(configFile = virFileBuildPath(driver->configDir,
+                                        def->name, ".xml"))) {
+        goto error;
     }
 
     if (!(xml = virNWFilterDefFormat(def))) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        "%s", _("failed to generate XML"));
-        return -1;
+        goto error;
     }
 
     virUUIDFormat(def->uuid, uuidstr);
-    ret = virXMLSaveFile(nwfilter->configFile,
+    ret = virXMLSaveFile(configFile,
                          virXMLPickShellSafeComment(def->name, uuidstr),
                          "nwfilter-edit", xml);
     VIR_FREE(xml);
 
+ error:
+    VIR_FREE(configFile);
     return ret;
 }
 
 
 int
-virNWFilterObjDeleteDef(virNWFilterObjPtr nwfilter)
+virNWFilterObjDeleteDef(const char *configDir,
+                        virNWFilterObjPtr nwfilter)
 {
-    if (!nwfilter->configFile) {
-        virReportError(VIR_ERR_INTERNAL_ERROR,
-                       _("no config file for %s"), nwfilter->def->name);
-        return -1;
+    int ret = -1;
+    char *configFile = NULL;
+
+    if (!(configFile = virFileBuildPath(configDir,
+                                        nwfilter->def->name, ".xml"))) {
+        goto error;
     }
 
-    if (unlink(nwfilter->configFile) < 0) {
+    if (unlink(configFile) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("cannot remove config for %s"),
                        nwfilter->def->name);
-        return -1;
+        goto error;
     }
 
-    return 0;
+    ret = 0;
+ error:
+    VIR_FREE(configFile);
+    return ret;
 }
 
 

src/conf/nwfilter_conf.h

@@ -551,7 +551,6 @@ typedef virNWFilterObj *virNWFilterObjPtr;
 struct _virNWFilterObj {
     virMutex lock;
 
-    char *configFile;
     int active;
     int wantRemoved;
 
@@ -612,10 +611,10 @@ virNWFilterObjPtr virNWFilterObjFindByName(virNWFilterObjListPtr nwfilters,
 
 
 int virNWFilterObjSaveDef(virNWFilterDriverStatePtr driver,
-                          virNWFilterObjPtr nwfilter,
                           virNWFilterDefPtr def);
 
-int virNWFilterObjDeleteDef(virNWFilterObjPtr nwfilter);
+int virNWFilterObjDeleteDef(const char *configDir,
+                            virNWFilterObjPtr nwfilter);
 
 virNWFilterObjPtr virNWFilterObjAssignDef(virNWFilterObjListPtr nwfilters,
                                           virNWFilterDefPtr def);

src/nwfilter/nwfilter_driver.c

@@ -554,7 +554,7 @@ nwfilterDefineXML(virConnectPtr conn,
     if (!(nwfilter = virNWFilterObjAssignDef(&driver->nwfilters, def)))
         goto cleanup;
 
-    if (virNWFilterObjSaveDef(driver, nwfilter, def) < 0) {
+    if (virNWFilterObjSaveDef(driver, def) < 0) {
         virNWFilterObjRemove(&driver->nwfilters, nwfilter);
         def = NULL;
         goto cleanup;
@@ -602,11 +602,9 @@ nwfilterUndefine(virNWFilterPtr obj)
         goto cleanup;
     }
 
-    if (virNWFilterObjDeleteDef(nwfilter) < 0)
+    if (virNWFilterObjDeleteDef(driver->configDir, nwfilter) < 0)
         goto cleanup;
 
-    VIR_FREE(nwfilter->configFile);
-
     virNWFilterObjRemove(&driver->nwfilters, nwfilter);
     nwfilter = NULL;
     ret = 0;