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NetBSD Security Advisory 2007-006
=================================
Topic: Local panics in display driver code
Version: NetBSD-current: source prior to July 28, 2007
NetBSD 4.0_BETA2 affected
NetBSD 3.1: affected
NetBSD 3.0.*: affected
NetBSD 3.0: affected
NetBSD 2.1: not affected
NetBSD 2.0.*: not affected
NetBSD 2.0: not affected
Severity: Local system crash
Fixed: NetBSD-current: July 28, 2007
NetBSD-4 branch: July 30, 2007
(4.0 will include the fix)
NetBSD-3-1 branch August 6, 2007
(3.1.1 will include the fix)
NetBSD-3-0 branch: August 6, 2007
(3.0.3 will include the fix)
NetBSD-3 branch: August 6, 2007
Abstract
========
A local user can cause the system to panic by passing out of bounds
values to display driver allocattr functions via an ioctl call.
This vulnerability has been assigned CVE reference CVE-2007-3654.
Technical Details
=================
vga_allocattr uses integer arguments as indicies into arrays of colors.
The vga_allocattr function does not check to see whether these arguments
are within the bounds of the arrays.
Due to the lack of bounds checking a negative or large value can be passed
to vga_allocattr which will cause it to access arbitrary memory locations,
resulting in a panic.
Other display driver functions are also vulnerable to this issue.
Solutions and Workarounds
=========================
To rectify these problems a kernel built from sources containing the
fixes must be installed and the system rebooted.
The following instructions describe how to upgrade your kernel
by updating your source tree and rebuilding and installing a new version
of the kernel.
For more information on how to do this, see:
http://www.NetBSD.org/guide/en/chap-kernel.html
* NetBSD-current:
Systems running NetBSD-current dated from before 2007-07-28
should be upgraded to NetBSD-current dated 2007-07-29 or later.
The following files need to be updated from the
netbsd-current CVS branch (aka HEAD):
sys/dev/ic/pcdisplay_subr.c
sys/dev/ic/vga.c
sys/dev/ic/vga_raster.c
sys/dev/isa/ega.c
sys/dev/pci/chipsfb.c
sys/dev/rasops/rasops.c
sys/dev/wscons/wsdisplay_vcons.c
To update from CVS, re-build, and re-install a kernel containing
the fix:
# cd src
# cvs update -d -P sys/dev
# build.sh tools kernel=KERNCONFFILE
* NetBSD 3.*:
Systems running NetBSD 3.* sources dated from before
2007-08-06 should be upgraded from NetBSD 3.* sources dated
2007-08-07 or later.
The following files need to be updated from the
netbsd-3, netbsd-3-0 or netbsd-3-1 branches:
sys/dev/ic/pcdisplay_subr.c
sys/dev/ic/vga.c
sys/dev/ic/vga_raster.c
sys/dev/isa/ega.c
sys/dev/rasops/rasops.c
To update from CVS, re-build, and re-install a kernel containing
the fix:
# cd src
# cvs update -r sys/dev/ic/pcdisplay_subr.c
# cvs update -r sys/dev/ic/vga.c
# cvs update -r sys/dev/ic/vga_raster.c
# cvs update -r sys/dev/isa/ega.c
# cvs update -r sys/dev/rasops/rasops.c
# build.sh tools kernel=KERNCONFFILE
Thanks To
=========
Venustech AD-LAB for discovering and reporting this problem.
Revision History
================
2007-09-13 Initial release
More Information
================
Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2007-006.tx...
Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/.
Copyright 2007, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.
$NetBSD: rt14768_vga.txt,v 1.7 2007/08/14 21:59:52 adrianp Exp $
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