On Sun, Mar 14, 2010 at 11:55 PM, Peter Hutterer
<[email protected]>wrote:
> 5780e59c4 "Take scroll buttons into accounts when allocating buttons."
> added
> a conditional to always have at least 7 buttons for devices with more than
> 3
> buttons. The exact number is nbuttons + 4, but for serial devices nbuttons
> is always WCM_MAX_MOUSE_BUTTONS - resulting in a segfault later on when
> arrays are accessed OOB.
>
> Reported-by: Ping Cheng <[email protected]>
> Signed-off-by: Peter Hutterer <[email protected]>
> ---
> Ping, I think this should fix your crash with the isdv4 branch.
>
Your patch (with "if (nbuttons < WCM_MAX_BUTTONS)" instead of "<=" though)
does fix the crash issue on my ISDV4 with touch system. However, I made a
new one with the following commit comments:
-------------------
The workaround that supports at least 7 buttons could cause
nbbuttons larger than WCM_MAX_BUTTONS, the maximum number of
buttons that is supported by the driver. This patch keeps
nbbuttons in its range.
This patch also fixes a driver crash issue on ISDV4 with touch
systems that may be caused by nbbuttons being larger than
WCM_MAX_BUTTONS. The "may be" is backed up by the following testing result:
1. linuxwacom-0.8.5-11 has the same block of code. However,
running linuxwacom-0.8.5-11 on the same ISDV4 system (Xorg 1.6.0)
without this patch doesn't have the issue.
2. Running xf86-input-wacom without this patch on a pen only
ISDV4 system doesn't have the issue either (Thomas Jaeger reported
the same positive testing result too).
So, there must be some other issues behind the crash that we don't
understand yet.
------------------------
Patch is attached. Please let me know if it makes sense to you or not.
Ping
>
> src/xf86Wacom.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/src/xf86Wacom.c b/src/xf86Wacom.c
> index 8656e63..3809dab 100644
> --- a/src/xf86Wacom.c
> +++ b/src/xf86Wacom.c
> @@ -608,7 +608,8 @@ static int wcmRegisterX11Devices (LocalDevicePtr local)
>
> /* if more than 3 buttons, offset by the four scroll buttons,
> * otherwise, alloc 7 buttons for scroll wheel. */
> - nbbuttons = (nbbuttons > 3) ? nbbuttons + 4 : 7;
> + if (nbuttons <= WCM_MAX_BUTTONS)
> + nbbuttons = (nbbuttons > 3) ? nbbuttons + 4 : 7;
> nbkeys = nbbuttons; /* Same number of keys since any button
> may be
> * configured as an either mouse button
> or key */
>
> --
> 1.6.6.1
>
>
From aa1aa20942cac09c4ce84a57a6d840caeaddf521 Mon Sep 17 00:00:00 2001
From: Ping Cheng <[email protected]>
Date: Mon, 15 Mar 2010 21:14:41 -0700
Subject: [PATCH] nbbuttons should be <= WCM_MAX_BUTTONS
The workaround that supports at least 7 buttons could cause
nbbuttons larger than WCM_MAX_BUTTONS, the maximum number of
buttons that is supported by the driver. This patch keeps
nbbuttons in its range.
This patch also fixes a driver crash issue on ISDV4 with touch
systems that may be caused by nbbuttons being larger than
WCM_MAX_BUTTONS. The "may be" is backed up by the following
testing result:
1. linuxwacom-0.8.5-11 has the same block of code. However,
running linuxwacom-0.8.5-11 on the same ISDV4 system (Xorg 1.6.0)
without this patch doesn't have the issue.
2. Running xf86-input-wacom without this patch on a pen only
ISDV4 system doesn't have the issue either (Thomas Jaeger reported
the same positive testing result too).
So, there must be some other issues behind the crash that we don't
understand yet.
Signed-off-by: Ping Cheng <[email protected]>
---
src/xf86Wacom.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)
diff --git a/src/xf86Wacom.c b/src/xf86Wacom.c
index 8685805..1f61503 100644
--- a/src/xf86Wacom.c
+++ b/src/xf86Wacom.c
@@ -606,6 +606,11 @@ static int wcmRegisterX11Devices (LocalDevicePtr local)
/* if more than 3 buttons, offset by the four scroll buttons,
* otherwise, alloc 7 buttons for scroll wheel. */
nbbuttons = (nbbuttons > 3) ? nbbuttons + 4 : 7;
+
+ /* make sure nbbuttons stays in the range */
+ if (nbbuttons > WCM_MAX_BUTTONS)
+ nbbuttons = WCM_MAX_BUTTONS;
+
nbkeys = nbbuttons; /* Same number of keys since any button may be
* configured as an either mouse button or key */
--
1.6.6.1
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