1 files changed, 4 insertions, 0 deletions
diff --git a/datapath-windows/ovsext/Stt.c b/datapath-windows/ovsext/Stt.c
index b6236fd7f..f98070f33 100644
--- a/datapath-windows/ovsext/Stt.c
+++ b/datapath-windows/ovsext/Stt.c
@@ -551,6 +551,10 @@ OvsSttDefragCleaner(PVOID data)
     BOOLEAN success = TRUE;
 
     while (success) {
+        if (&OvsSttSpinLock == NULL) {
+            /* Lock has been freed by 'OvsCleanupSttDefragmentation()' */
+            break;
+        }
         NdisAcquireSpinLock(&OvsSttSpinLock);
         if (context->exit) {
             NdisReleaseSpinLock(&OvsSttSpinLock);