dix: fix cursor refcounting

The cursor is referenced during CopyGrab(), thus doesn't need to be handled
manually anymore. It does need to be refcounted for temp grabs though.

The oldGrab handling in ProcGrabPointer is a leftover from the cursor in the
grab being refcounted, but the grab itself being a static struct in the
DeviceIntRec. Now that all grabs are copied, this lead to a double-free of
the cursor (Reproduced in Thunderbird, dragging an email twice (or more
often) causes a crash).

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

1 files changed, 4 insertions, 16 deletions

diff --git a/dix/events.c b/dix/events.c
index 7464db586..8124ca93d 100644
--- a/dix/events.c
+++ b/dix/events.c
@@ -1491,9 +1491,6 @@ ActivatePointerGrab(DeviceIntPtr mouse, GrabPtr grab,
         grabinfo->grabTime = syncEvents.time;
     else
         grabinfo->grabTime = time;
-    if (grab->cursor)
-        grab->cursor->refcnt++;
-    BUG_WARN(grabinfo->grab != NULL);
     grabinfo->grab = AllocGrab(grab);
     grabinfo->fromPassiveGrab = isPassive;
     grabinfo->implicitGrab = autoGrab & ImplicitGrabMask;
@@ -1552,8 +1549,6 @@ DeactivatePointerGrab(DeviceIntPtr mouse)
     if (grab->confineTo)
         ConfineCursorToWindow(mouse, GetCurrentRootWindow(mouse), FALSE, FALSE);
     PostNewCursor(mouse);
-    if (grab->cursor)
-        FreeCursor(grab->cursor, (Cursor) 0);
 
     if (!wasImplicit && grab->grabtype == XI2)
         ReattachToOldMaster(mouse);
@@ -4860,7 +4855,6 @@ ProcGrabPointer(ClientPtr client)
     GrabPtr grab;
     GrabMask mask;
     WindowPtr confineTo;
-    CursorPtr oldCursor;
     BYTE status;
 
     REQUEST(xGrabPointerReq);
@@ -4883,15 +4877,10 @@ ProcGrabPointer(ClientPtr client)
             return rc;
     }
 
-    oldCursor = NullCursor;
     grab = device->deviceGrab.grab;
 
-    if (grab) {
-        if (grab->confineTo && !confineTo)
-            ConfineCursorToWindow(device, GetCurrentRootWindow(device), FALSE,
-                                  FALSE);
-        oldCursor = grab->cursor;
-    }
+    if (grab && grab->confineTo && !confineTo)
+        ConfineCursorToWindow(device, GetCurrentRootWindow(device), FALSE, FALSE);
 
     mask.core = stuff->eventMask;
 
@@ -4901,9 +4890,6 @@ ProcGrabPointer(ClientPtr client)
     if (rc != Success)
         return rc;
 
-    if (oldCursor && status == GrabSuccess)
-        FreeCursor(oldCursor, (Cursor) 0);
-
     rep = (xGrabPointerReply) {
         .type = X_Reply,
         .status = status,
@@ -5107,6 +5093,8 @@ GrabDevice(ClientPtr client, DeviceIntPtr dev,
             xi2mask_merge(tempGrab->xi2mask, mask->xi2mask);
         tempGrab->device = dev;
         tempGrab->cursor = cursor;
+        if (cursor)
+            tempGrab->cursor->refcnt++;
         tempGrab->confineTo = confineTo;
         tempGrab->grabtype = grabtype;
         (*grabInfo->ActivateGrab) (dev, tempGrab, time, FALSE);