SUSE Linux Advisory: kernel

Jun 18, 2004, 03:15 (0 Talkback[s])

SUSE Security Announcement

Package: kernel Announcement-ID: SuSE-SA:2004:017 Date: Wednesday, Jun 16th 2004 15:20 MEST Affected products: 8.0, 8.1, 8.2, 9.0, 9.1 SuSE Linux Database Server, SuSE eMail Server III, 3.1 SuSE Linux Enterprise Server 7, 8 SuSE Linux Firewall on CD/Admin host SuSE Linux Connectivity Server SuSE Linux Office Server Vulnerability Type: local denial-of-service attack Severity (1-10): 4 SUSE default package: no Cross References: CAN-2004-0554

Content of this advisory:

security vulnerability resolved:
- floating point exception causes system crash problem description, discussion, solution and upgrade information
pending vulnerabilities, solutions, workarounds:
- icecast
- sitecopy
- cadaver
- OpenOffice_org
- tripwire
- postgresql
- lha
- XDM
- mod_proxy 3) standard appendix (further information)

1) problem description, brief discussion, solution, upgrade information

The Linux kernel is vulnerable to a local denial-of-service attack. By using a C program it is possible to trigger a floating point exception that puts the kernel into an unusable state. To execute this attack a malicious user needs shell access to the victim's machine.
The severity of this bug is considered low because local denial-ofservice attacks are hard to prevent in general. Additionally the bug is limited to x86 and x86_64 architecture.

SPECIAL INSTALL INSTRUCTIONS:

The following paragraphs will guide you through the installation process in a step-by-step fashion. The character sequence "****" marks the beginning of a new paragraph. In some cases, the steps outlined in a particular paragraph may or may not be applicable to your situation.
Therefore, please make sure to read through all of the steps below before attempting any of these procedures. All of the commands that need to be executed are required to be run as the superuser (root). Each step relies on the steps before it to complete successfully.
Note: The update packages for the SuSE Linux Enterprise Server 7 (SLES7) are being tested at the moment and will be published as soon as possible.

Step 1: Determine the needed kernel type

Please use the following command to find the kernel type that is installed on your system:

      rpm -qf /boot/vmlinuz

Following are the possible kernel types (disregard the version and build number following the name separated by the "-" character)

      k_deflt   # default kernel, good for most systems.
      k_i386    # kernel for older processors and chipsets
      k_athlon  # kernel made specifically for AMD Athlon(tm) family processors
      k_psmp    # kernel for Pentium-I dual processor systems
      k_smp     # kernel for SMP systems (Pentium-II and above)
      k_smp4G   # kernel for SMP systems which supports a maximum of 4G of RAM
      kernel-64k-pagesize
      kernel-bigsmp
      kernel-default
      kernel-smp

Step 2: Download the package for your system
Please download the kernel RPM package for your distribution with the name as indicated by Step 1. The list of all kernel rpm packages is appended below. Note: The kernel-source package does not contain a binary kernel in bootable form. Instead, it contains the sources that the binary kernel rpm packages are created from. It can be used by administrators who have decided to build their own kernel. Since the kernel-source.rpm is an installable (compiled) package that contains sources for the linux kernel, it is not the source RPM for the kernel RPM binary packages.

The kernel RPM binary packages for the distributions can be found at the locations below ftp://ftp.suse.com/pub/suse/i386/update/.
```
      8.0/images/
      8.1/rpm/i586
      8.2/rpm/i586
      9.0/rpm/i586
      9.1/rpm/i586
```
After downloading the kernel RPM package for your system, you should verify the authenticity of the kernel rpm package using the methods as listed in section 3) of each SUSE Security Announcement.
Step 3: Installing your kernel rpm package
Install the rpm package that you have downloaded in Steps 3 or 4 with the command
```
        rpm -Uhv --nodeps --force <K_FILE.RPM>
```
where <K_FILE.RPM> is the name of the rpm package that you downloaded.
Warning: After performing this step, your system will likely not be able to boot if the following steps have not been fully followed.

If you run SUSE LINUX 8.1 and haven't applied the kernel update (SUSE-SA:2003:034), AND you are using the freeswan package, you also need to update the freeswan rpm as a dependency as offered by YOU (YaST Online Update). The package can be downloaded from
ftp://ftp.suse.com/pub/suse/i386/update/8.1/rpm/i586/
Step 4: configuring and creating the initrd
The initrd is a ramdisk that is loaded into the memory of your system together with the kernel boot image by the bootloader. The kernel uses the content of this ramdisk to execute commands that must be run before the kernel can mount its actual root filesystem. It is usually used to initialize SCSI drivers or NIC drivers for diskless operation.

The variable INITRD_MODULES in /etc/sysconfig/kernel determines which kernel modules will be loaded in the initrd before the kernel has mounted its actual root filesystem. The variable should contain your SCSI adapter (if any) or filesystem driver modules.

With the installation of the new kernel, the initrd has to be re-packed with the update kernel modules. Please run the command
```
      mk_initrd
```
as root to create a new init ramdisk (initrd) for your system. On SuSE Linux 8.1 and later, this is done automatically when the RPM is installed.
Step 5: bootloader
If you run a SUSE LINUX 8.x, SLES8, or SUSE LINUX 9.x system, there are two options:
Depending on your software configuration, you have either the lilo bootloader or the grub bootloader installed and initialized on your system.
The grub bootloader does not require any further actions to be performed after the new kernel images have been moved in place by the rpm Update command.
If you have a lilo bootloader installed and initialized, then the lilo program must be run as root. Use the command
```
      grep LOADER_TYPE /etc/sysconfig/bootloader
```
to find out which boot loader is configured. If it is lilo, then you must run the lilo command as root. If grub is listed, then your system does not require any bootloader initialization.
Warning: An improperly installed bootloader may render your system unbootable.
Step 6: reboot
If all of the steps above have been successfully completed on your system, then the new kernel including the kernel modules and the initrd should be ready to boot. The system needs to be rebooted for the changes to become active. Please make sure that all steps have completed, then reboot using the command
```
        shutdown -r now
```
or
```
        init 6
```
Your system should now shut down and reboot with the new kernel.

There is no workaround known.

Please download the update package for your distribution and verify its integrity by the methods listed in section 3) of this announcement. Then, install the package using the command "rpm -Fhv file.rpm" to apply the update.
Our maintenance customers are being notified individually. The packages are being offered to install from the maintenance web.

Intel i386 Platform:

Opteron x86_64 Platform:

SuSE-9.1:
ftp://ftp.suse.com/pub/suse/x86_64/update/9.1/rpm/x86_64/kernel-source-2.6.5-7.75.x86_64.rpm 1c878b1e29a9bea40547637b6a307b2d
ftp://ftp.suse.com/pub/suse/x86_64/update/9.1/rpm/x86_64/kernel-default-2.6.5-7.75.x86_64.rpm 16de3ee2390bb2b92f9fe50451d4f082
ftp://ftp.suse.com/pub/suse/x86_64/update/9.1/rpm/x86_64/kernel-smp-2.6.5-7.75.x86_64.rpm c310268daa83f18fcfd4cf19434f06e0
source rpm(s):
ftp://ftp.suse.com/pub/suse/x86_64/update/9.1/rpm/src/kernel-source-2.6.5-7.75.src.rpm 2fed0a8f3936027261add7d1cbfa5341
ftp://ftp.suse.com/pub/suse/x86_64/update/9.1/rpm/src/kernel-default-2.6.5-7.75.nosrc.rpm 9ad26d15566337c83273121390ea4e32
ftp://ftp.suse.com/pub/suse/x86_64/update/9.1/rpm/src/kernel-smp-2.6.5-7.75.nosrc.rpm 352951be42b3093efb0148320a6f4c27

SuSE-9.0:
ftp://ftp.suse.com/pub/suse/x86_64/update/9.0/rpm/x86_64/kernel-source-2.4.21-226.x86_64.rpm ced9c66ffa28bf7e7c795781f92083fe
ftp://ftp.suse.com/pub/suse/x86_64/update/9.0/rpm/x86_64/k_deflt-2.4.21-226.x86_64.rpm 60539bc47e8cac0664ac5ca824d311e0
ftp://ftp.suse.com/pub/suse/x86_64/update/9.0/rpm/x86_64/k_smp-2.4.21-226.x86_64.rpm 083aeedd2a88ccc2e00c8f66cd61b81c
source rpm(s):
ftp://ftp.suse.com/pub/suse/x86_64/update/9.0/rpm/src/kernel-source-2.4.21-226.src.rpm 58c40a206f6f615daa3486fc6d6ade38
ftp://ftp.suse.com/pub/suse/x86_64/update/9.0/rpm/src/k_deflt-2.4.21-226.src.rpm 1c234f6c0475680b41c644c575ff8ef6
ftp://ftp.suse.com/pub/suse/x86_64/update/9.0/rpm/src/k_smp-2.4.21-226.src.rpm e9b90824615859405b1979793662bc0d

2) Pending vulnerabilities in SUSE Distributions and Workarounds:

icecast
The icecast service is vulnerable to a remote denial-of-service attack. Update packages will be available soon.
sitecopy
The sitecopy package includes a vulnerable version of the neon library (CAN-2004-0179, CAN-2004-0398). Update packages will be available soon.
cadaver
The cadaver package includes a vulnerable version of the neon library (CAN-2004-0179, CAN-2004-0398). Update packages will be available soon.
OpenOffice_org
The OpenOffice_org package includes a vulnerable version of the neon library (CAN-2004-0179, CAN-2004-0398). Update packages will be available soon.
tripwire
A format string bug in tripwire can be exploited locally to gain root permissions. Update packages will be available soon.
postgresql
A buffer overflow in psqlODBC could be exploited to crash the application using it. E.g. a PHP script that uses ODBC to access a PostgreSQL database can be utilized to crash the surrounding Apache web-server. Other parts of PostgreSQL are not affected. Update packages will be available soon.
lha
Minor security fix for a buffer overflow while handling command line options. This buffer overflow could be exploited in conjunction with other mechanisms to gain higher privileges or access the system remotely.
XDM/XFree86
This update resolves random listening to ports by XDM that allows to connect via the XDMCP. SUSE LINUX 9.1 is affected only. New packages are currently being tested and will be available soon.
mod_proxy
A buffer overflow can be triggered by malicious remote servers that return a negative Content-Length value. This vulnerability can be used to execute commands remotely New packages are currently being tested and will be available soon.

3) standard appendix: authenticity verification, additional information

Package authenticity verification:
SUSE update packages are available on many mirror ftp servers around the world. While this service is considered valuable and important to the free and open source software community, many users wish to be certain as to be the origin of the package and its content before installing the package. There are two independent verification methods that can be used to prove the authenticity of a downloaded file or rpm package:
1. md5sums as provided in the (cryptographically signed) announcement.
2. using the internal gpg signatures of the rpm package.
3. execute the command
  md5sum <name-of-the-file.rpm>
  after you have downloaded the file from a SUSE ftp server or its mirrors. Then, compare the resulting md5sum with the one that is listed in the announcement. Since the announcement containing the checksums is cryptographically signed (usually using the key security@suse.de), the checksums offer proof of the authenticity of the package.
  We recommend against subscribing to security lists which cause the email message containing the announcement to be modified so that the signature does not match after transport through the mailing list software.
  Downsides: You must be able to verify the authenticity of the announcement in the first place. If RPM packages are being rebuilt and a new version of a package is published on the ftp server, all md5 sums for the files are useless.
4. rpm package signatures provide an easy way to verify the authenticity of an rpm package. Use the command
  rpm -v --checksig <file.rpm>
  to verify the signature of the package, where <file.rpm> is the filename of the rpm package that you have downloaded. Of course, package authenticity verification can only target an un-installed rpm package file.
  Prerequisites:
  1. gpg is installed
  2. The package is signed using a certain key. The public part of this key must be installed by the gpg program in the directory ~/.gnupg/ under the user's home directory who performs the signature verification (usually root). You can import the key that is used by SUSE in rpm packages for SUSE Linux by saving this announcement to a file ("announcement.txt") and running the command (do "su -" to be root):
    gpg --batch; gpg < announcement.txt | gpg --import
    SUSE Linux distributions version 7.1 and thereafter install the key "build@suse.de" upon installation or upgrade, provided that the package gpg is installed. The file containing the public key is placed at the top-level directory of the first CD (pubring.gpg) and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .
SUSE runs two security mailing lists to which any interested party may subscribe:
suse-security@suse.com
general/linux/SUSE security discussion.
All SUSE security announcements are sent to this list. To subscribe, send an email to
<suse-security-subscribe@suse.com>.
suse-security-announce@suse.com
SUSE's announce-only mailing list.
Only SUSE's security announcements are sent to this list. To subscribe, send an email to
<suse-security-announce-subscribe@suse.com>.

For general information or the frequently asked questions (faq) send mail to:

<suse-security-info@suse.com> or
<suse-security-faq@suse.com> respectively.

SUSE's security contact is <security@suse.com> or <security@suse.de>.
The <security@suse.de> public key is listed below.

The information in this advisory may be distributed or reproduced, provided that the advisory is not modified in any way. In particular, it is desired that the clear-text signature must show proof of the authenticity of the text.
SUSE Linux AG makes no warranties of any kind whatsoever with respect to the information contained in this security advisory.

Type Bits/KeyID Date User ID
pub 2048R/3D25D3D9 1999-03-06 SuSE Security Team <security@suse.de>
pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <build@suse.de>

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