修复uevent crash

Signed-off-by: Nchengjinsong2 <chengjinsong2@huawei.com>

ueventd/ueventd_device_handler.c

@@ -134,7 +134,9 @@ static void SetDeviceLable(const char *path, char **symLinks)
         if (strncmp(linkName, byNamePath, strlen(byNamePath)) == 0) {
             (void)Restorecon(linkName);
             lgetfilecon(linkName, &context);
-            setfilecon(path, context);
+            if (context != NULL) {
+                setfilecon(path, context);
+            }
             return;
         }
     }