tag 681796 + patch thanks On Sat, 28 Jul 2012, Julien Cristau wrote:
> It's helpful, yes, thanks. Could you forward it upstream to > https://bugs.freedesktop.org/enter_bug.cgi?product=xorg&component=Server/Input/Core so upstream seems to boiled it down and provided a patch. I have adopted the patch for version in Debian 1.6.2 and attaching it here... 2nd day of a normal flight. -- Yaroslav O. Halchenko Postdoctoral Fellow, Department of Psychological and Brain Sciences Dartmouth College, 419 Moore Hall, Hinman Box 6207, Hanover, NH 03755 Phone: +1 (603) 646-9834 Fax: +1 (603) 646-1419 WWW: http://www.linkedin.com/in/yarik
Author: Peter Hutterer
Subject: When disabling the device, reset num_active_touches to zero.
Otherwise, num_active_touches stays at the value it was on DeviceOff().
Future touches add to that value until the index may go past
priv->open_slots[]. That causes spurious memory corruption on touch ends.
And as of 55fc42e7c9b4948cadd4f98ef7b6a3b12e268e3e we ignore pre-existing
touches anyway.
Test-case:
- place num_touches fingers on the touchpad
- xinput disable <device>
- lift fingers
- xinput enable <device>
- place finger on device, num_active_touches is now (num_touches + 1)
Signed-off-by: Peter Hutterer <peter.hutte...@who-t.net>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=52496
Bug-Debian: http://bugs.debian.org/681796
Last-Update: 2012-08-30
--- a/src/synaptics.c
+++ b/src/synaptics.c
@@ -1153,6 +1153,7 @@ SynapticsReset(SynapticsPrivate * priv)
priv->lastButtons = 0;
priv->prev_z = 0;
priv->prevFingers = 0;
+ priv->num_active_touches = 0;
#ifdef HAVE_MULTITOUCH
memset(priv->open_slots, 0, priv->num_slots * sizeof(int));
#endif
@@ -3118,6 +3119,7 @@ UpdateTouchState(InputInfoPtr pInfo, str
if (hw->slot_state[i] == SLOTSTATE_OPEN) {
priv->open_slots[priv->num_active_touches] = i;
priv->num_active_touches++;
+ BUG_WARN(priv->num_active_touches > priv->num_slots);
}
else if (hw->slot_state[i] == SLOTSTATE_CLOSE) {
Bool found = FALSE;
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