[Bug 730488] Re: [Lucid] xf86ScaleAxis problems with high resolution devices

[Martin Pitt]

Accepted xorg-server into lucid-proposed, the package will build now and
be available in a few hours. Please test and give feedback here. See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to
enable and use -proposed. Thank you in advance!

** Tags added: verification-needed

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https://bugs.launchpad.net/bugs/730488

Title:
  [Lucid] xf86ScaleAxis problems with high resolution devices

Status in “xorg-server” package in Ubuntu:
  Fix Released
Status in “xorg-server” source package in Lucid:
  Fix Committed
Status in “xorg-server” source package in Natty:
  Fix Released

Bug description:
  [Impact]
  On certain higher resolution touchpads, an integer overflow can occur since their range exceeds the maximum int value.

  This issue can crop up on Lucid if the user self-compiles -wacom or
  uses a backport package from a PPA.  It does not affect the shipped
  version of -wacom in Lucid.

  [Development Solution]
  This was fixed upstream by using a 64-bit integer rather than 32-bit to extend the range.  This fix is included in the upstream version of xorg-server we are shipping in natty.

  [Stable Solution]
  A backport of the fix has been made for Lucid.
  https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/730488/+attachment/1891113/+files/xf86-scale-high-resolution.diff

  [Test Case]
  See below (requires affected hardware and rebuilding -wacom on Lucid)

  [Regression Potential]
  None.  No APIs are changed, and increase of the data type has no other code effects.

  [Original Report]
  The xf86ScaleAxis function is used to scale x and y axis values of input devices between different resolutions. Due to internal integer overflow, the acceptable value range for its arguments are limited below their type (signed 32bit integer). This imposes a problem for high resolution devices, like the wacom Intuos 4 L, which have a total horizontal resolution of 65024. Example: when doing a scaling with a range of more than 46340 (Sxhigh-Sxlow), the integer X will wrap into negative values, and truncated to 0 at the end.

  Among other devices, this problem affects wacom Intuos 4 L and XL
  tablets when compiling the xf86-input-wacom driver version 0.10.9 and
  above. Previous versions work, because they don't use the
  xf86ScaleAxis function. With current xorg releases this problem does
  not happen either, because a upstream patch
  (http://lists.x.org/archives/xorg-devel/2010-April/007333.html)
  already extends the acceptable value range. A solution would be to
  include this patch into 10.04, because there is still quite a time
  till the next LTS.

  If there is a chance for getting this patch included into 10.04 I'm
  willing to make a patch specific for the current xorg-server-1.7.6
  package and test it.