[XENIFACE-SYNC 3/3] xeniface: Don't remove a NULL watch on resume

[Césaire Mounah <cesaire.mounah@xxxxxxxxxx>]

If StartWatch() fails, Watch->WatchHandle stays NULL. On the next
suspend/resume, SessionWatchThread() then passes NULL to
XENBUS_STORE(WatchRemove), which dereferences it in xenbus.

Only remove the watch if it was set up, as the other callers already
do, and still call StartWatch() so the watch is set up again.

Signed-off-by: Césaire Mounah <cesaire.mounah@xxxxxxxxxx>
---
 src/xeniface/wmi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/xeniface/wmi.c b/src/xeniface/wmi.c
index f2b4802..5ba7645 100644
--- a/src/xeniface/wmi.c
+++ b/src/xeniface/wmi.c
@@ -994,8 +994,10 @@ WatchCallbackThread(
                 Watch->SuspendCount = XENBUS_SUSPEND(GetCount, 
&Watch->Fdo->SuspendInterface);
                 Info("SessionSuspendResumeUnwatch %p\n", Watch->WatchHandle);
 
-                XENBUS_STORE(WatchRemove, &Watch->Fdo->StoreInterface, 
Watch->WatchHandle);
-                Watch->WatchHandle = NULL;
+                if (Watch->WatchHandle != NULL) {
+                    XENBUS_STORE(WatchRemove, &Watch->Fdo->StoreInterface, 
Watch->WatchHandle);
+                    Watch->WatchHandle = NULL;
+                }
                 StartWatch(Watch->Fdo, Watch);
             } else {
                 FireWatch(Watch);
-- 
2.55.0.windows.5



--
Césaire Mounah | Vates Windows Guest Tools Engineer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech