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dix: Correctly save replayed event into GrabInfoRec 

When processing events we operate on InternalEvent pointers. They may
actually refer to a an instance of DeviceEvent, GestureEvent or any
other event that comprises the InternalEvent union. This works well in
practice because we always look into event type before doing anything,
except in the case of copying the event.

*dst_event = *src_event would copy whole InternalEvent event and would
cause out of bounds read in case the pointed to event was not
InternalEvent but e.g. DeviceEvent.

This regression has been introduced in
23a8b62d34.

Fixes https://gitlab.freedesktop.org/xorg/xserver/-/issues/1261

Signed-off-by: Povilas Kanapickas <povilas@radix.lt>
This commit is contained in:
Povilas Kanapickas 2022-01-23 22:18:52 +02:00
parent 34b870da88
commit 6ef5c05728
3 changed files with 18 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Xi/exevents.c
View File

@ -1524,7 +1524,7 @@ DeliverTouchEmulatedEvent(DeviceIntPtr dev, TouchPointInfoPtr ti,
g = AllocGrab(devgrab);
BUG_WARN(!g);
*dev->deviceGrab.sync.event = *ev;
CopyPartialInternalEvent(dev->deviceGrab.sync.event, ev);
/* The listener array has a sequence of grabs and then one event
* selection. Implicit grab activation occurs through delivering an

18
dix/events.c
View File

@ -467,6 +467,20 @@ WindowXI2MaskIsset(DeviceIntPtr dev, WindowPtr win, xEvent *ev)
return xi2mask_isset(inputMasks->xi2mask, dev, evtype);
}
/**
* When processing events we operate on InternalEvent pointers. They may actually refer to a
* an instance of DeviceEvent, GestureEvent or any other event that comprises the InternalEvent
* union. This works well in practice because we always look into event type before doing anything,
* except in the case of copying the event. Any copying of InternalEvent should use this function
* instead of doing *dst_event = *src_event whenever it's not clear whether source event actually
* points to full InternalEvent instance.
*/
void
CopyPartialInternalEvent(InternalEvent* dst_event, const InternalEvent* src_event)
{
memcpy(dst_event, src_event, src_event->any.length);
}
Mask
GetEventMask(DeviceIntPtr dev, xEvent *event, InputClients * other)
{
@ -3873,7 +3887,7 @@ void ActivateGrabNoDelivery(DeviceIntPtr dev, GrabPtr grab,
if (grabinfo->sync.state == FROZEN_NO_EVENT)
grabinfo->sync.state = FROZEN_WITH_EVENT;
*grabinfo->sync.event = *real_event;
CopyPartialInternalEvent(grabinfo->sync.event, real_event);
}
static BOOL
@ -4455,7 +4469,7 @@ FreezeThisEventIfNeededForSyncGrab(DeviceIntPtr thisDev, InternalEvent *event)
case FREEZE_NEXT_EVENT:
grabinfo->sync.state = FROZEN_WITH_EVENT;
FreezeThaw(thisDev, TRUE);
*grabinfo->sync.event = *event;
CopyPartialInternalEvent(grabinfo->sync.event, event);
break;
}
}

1
include/input.h
View File

@ -676,6 +676,7 @@ extern void GestureEmitGestureEndToOwner(DeviceIntPtr dev, GestureInfoPtr gi);
extern void ProcessGestureEvent(InternalEvent *ev, DeviceIntPtr dev);
/* misc event helpers */
extern void CopyPartialInternalEvent(InternalEvent* dst_event, const InternalEvent* src_event);
extern Mask GetEventMask(DeviceIntPtr dev, xEvent *ev, InputClientsPtr clients);
extern Mask GetEventFilter(DeviceIntPtr dev, xEvent *event);
extern Bool WindowXI2MaskIsset(DeviceIntPtr dev, WindowPtr win, xEvent *ev);