Make sure window->optional is allocated before assigning it.

DeletePassiveGrabFromList() may remove the window optional, so we need to
re-alloc it if it isn't there anymore.

Thanks to Colin Harrison for spotting the bug.

1 files changed, 6 insertions, 6 deletions

diff --git a/dix/grabs.c b/dix/grabs.c
index cecd7ec39..2210cd05e 100644
--- a/dix/grabs.c
+++ b/dix/grabs.c
@@ -322,12 +322,6 @@ AddPassiveGrabToList(GrabPtr pGrab)
 	}
     }
 
-    if (!pGrab->window->optional && !MakeWindowOptional (pGrab->window))
-    {
-	FreeGrab(pGrab);
-	return BadAlloc;
-    }
-
     /* Remove all grabs that match the new one exactly */
     for (grab = wPassiveGrabs(pGrab->window); grab; grab = grab->next)
     {
@@ -338,6 +332,12 @@ AddPassiveGrabToList(GrabPtr pGrab)
 	} 
     }
 
+    if (!pGrab->window->optional && !MakeWindowOptional (pGrab->window))
+    {
+	FreeGrab(pGrab);
+	return BadAlloc;
+    }
+
     pGrab->next = pGrab->window->optional->passiveGrabs;
     pGrab->window->optional->passiveGrabs = pGrab;
     if (AddResource(pGrab->resource, RT_PASSIVEGRAB, (pointer)pGrab))