===================================================================== CERT-Renater Note d'Information No. 2004/VULN518 _____________________________________________________________________ DATE : 01/12/2004 HARDWARE PLATFORM(S) : / OPERATING SYSTEM(S) : Linux. ====================================================================== ______________________________________________________________________________ SUSE Security Announcement Package: kernel Announcement-ID: SUSE-SA:2004:042 Date: Wednesday, Dec 1st 2004 15:00 MEST Affected products: 8.1, 8.2, 9.0, 9.1, 9.2 SUSE Linux Enterprise Server 8, 9 SUSE LINUX Desktop 1.0 Novell Linux Desktop 9 Vulnerability Type: local and remote denial of service Severity (1-10): 7 SUSE default package: yes Cross References: CAN-2004-0883 CAN-2004-0949 CAN-2004-1070 CAN-2004-1071 CAN-2004-1072 CAN-2004-1073 CAN-2004-1074 Content of this advisory: 1) security vulnerability resolved: - kernel remote and local denial of service problems problem description 2) solution/workaround 3) special instructions and notes 4) package location and checksums 5) pending vulnerabilities, solutions, workarounds: - see SUSE Security Summary Report 6) standard appendix (further information) ______________________________________________________________________________ 1) problem description, brief discussion The Linux kernel is the base of the SUSE Linux system. Several security problems have been found and addressed by the SUSE Security Team. The following issues are present in all SUSE Linux based products. - Several remote denial of service conditions have been found in the smbfs file system, reported by Stefan Esser. The vulnerability could be used by a hostile SMB server (or an attacker injecting packets into the network) to crash the clients kernel. These issues have been assigned the Mitre CVE IDs CAN-2004-0883 and CAN-2004-0949. We thank Stefan Esser for reporting this issue and providing patches. - Paul Starzetz of isec.pl found several missing boundary checks in the ELF loader routines of the Linux kernel which could potentially lead a local attacker to gain root privileges by using handmade ELF binaries. These issues have been assigned the Mitre CVE IDs CAN-2004-1070,CAN-2004-1071,CAN-2004-1072, and CAN-2004-1073. We thank Paul for reporting this issue and Chris Wright for providing a patch to fix the issue. - Handcrafted a.out binaries could be used to trigger a local denial of service condition in both 2.4 and 2.6 Linux kernels, allowing a local attacker to render the system unusable. Fixes for this problem were done by Chris Wright. This issue has been assigned the Mitre CVE ID CAN-2004-1074. We wish to thank Chris for providing patches. - SUSE Linux 9.1 and SUSE Linux Enterprise Server 9 now contain stricter checks what commands you can send to read-only opened CD devices. This way local attackers only having read access to the device will not be able to destroy the firmware of SCSI related devices. This update will break the k3b and the dvd+rw-tools packages. We have released fixed versions of those packages. - The SUSE Linux 8.1, 8.2, and 9.0 and the SUSE Linux Desktop 1.0 kernel were missing the kNFSD remote denial of service fix. The respective fixes are now in the released kernels. Also, the following critical bugs were fixed by this update: - A very small race condition on SMP systems with more than 4GB of memory that could expose foreign memory pages was found and fixed by Andrea Arcangeli of SUSE. - On SUSE Linux Enterprise Server 9 a memory corruption in the NFS readdirplus command could lead to kernel crashes and potentially corruption of data on disk. This problem was fixed. - On SUSE Linux 9.2 the "dazuko" kernel module of the "antivir" RPM package caused problems with programs using Linux capabilities. The module was fixed. - A security fix for buffer overflows in the decnet protocol driver was incorrect and caused kernel crashes. 2) solution/workaround There is no workaround, please install the fixed kernels. 3) special instructions and notes 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. **** 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 chip sets 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/. 8.1/rpm/i586 8.2/rpm/i586 9.0/rpm/i586 9.1/rpm/i586 9.2/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 where 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. 4) package location and checksums 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. ______________________________________________________________________________ 5) Pending vulnerabilities in SUSE Distributions and Workarounds: Please see our weekly summary report. ______________________________________________________________________________ 6) standard appendix: authenticity verification, additional information - Package authenticity verification: SUSE update packages are available on many mirror ftp servers all over the world. While this service is being considered valuable and important to the free and open source software community, many users wish to be sure about the origin of the package and its content before installing the package. There are two verification methods that can be used independently from each other 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. 1) execute the command md5sum after you 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 show proof of the authenticity of the package. We disrecommend to subscribe 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. 2) rpm package signatures provide an easy way to verify the authenticity of an rpm package. Use the command rpm -v --checksig to verify the signature of the package, where 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: a) gpg is installed b) 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-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 . For general information or the frequently asked questions (FAQ) send mail to: or respectively. ===================================================================== SUSE's security contact is or . The 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 shows 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 pub 1024D/9C800ACA 2000-10-19 SuSE Package Signing Key ====================================================================== ========================================================= Les serveurs de référence du CERT-Renater http://www.urec.fr/securite http://www.cru.fr/securite http://www.renater.fr ========================================================= + CERT-RENATER | tel : 01-53-94-20-44 + + 151 bd de l'Hopital | fax : 01-53-94-20-41 + + 75013 Paris | email: certsvp@renater.fr + =========================================================