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SuSE Security Announcement: kernel

May 19, 2001, 01:56 (0 Talkback[s])
Date: Thu, 17 May 2001 16:44:59 +0200 (MEST)
From: Roman Drahtmueller <<A HREF="mailto:draht@suse.de">draht@suse.de>
Subject: SuSE Security Announcement: kernel (SuSE-SA:2001:18)


                        SuSE Security Announcement

        Package:                kernel
        Announcement-ID:        SuSE-SA:2001:18
        Date:                   Thursday, May 17th, 2000 16:40 MET
        Affected SuSE versions: (6.1, 6.2), 6.3, 6.4, 7.0, 7.1
        Vulnerability Type:     local root compromise
        Severity (1-10):        7
        SuSE default package:   yes
        Other affected systems: All Linux systems using a v2.2 kernel

    Content of this advisory:
        1) security vulnerability resolved: kernel
           Problem, Workaround, Recommended solution, Instructions, Notes,
        2) Acknowledgements
        3) standard appendix (further information)


1)  The Problem, Workaround, Recommended solution, Instructions, Notes,

  The Problem:

    The SuSE Linux kernel is a standard kernel, enhanced with a set of
    additional drivers and other improvements, to suit the end-user's
    demand for a great variety of drivers for all kind of hardware.
    Multiple security vulnerabilities have been found in all Linux kernels
    of version 2.2 before version 2.2.19. Most of the found errors allow
    a local attacker to gain root privileges. None of the found errors
    in the v2.2 linux kernel make it possible for a remote attacker to
    gain access to the system or to elevate privileges from the outside
    of the system. Thanks to Alan Cox, a summary of these errors can be
    found at http://www.linux.org.uk/VERSION/relnotes.2219.html .
    One of the numerous features in the SuSE Linux kernels is support
    for reiserfs, a fast, stable logging filesystem. In addition to the
    bugs listed at www.linux.org.uk, the SuSE Linux kernel contains a fix
    for a race condition between mmap(2) and write(2) in reiserfs that
    can expose raw data from the disk to an unprivileged user (this
    problem affected the ufs and ext2fs drivers in FreeBSD systems,
    see FreeBSD-SA-01:30.ufs-ext2fs at http://www.freebsd.org/security/).
    Please see the acknowledgement section 2) below for credits on
    hunting these bugs and fixing them.


    In order to solve the security problems, it is recommended to update
    the kernel to version 2.2.19. Some problems (ptrace race) can be
    circumvented by removing all suid and sgid bits from all binaries
    in the system. Since this does not help against the other errors,
    there is no appropriate temporary workaround against all of the
    known problems except for locking out users with shell access.
    Advanced Linux users may decide to compile and install the 2.2.19
    kernel themselves by hand. This requires some experience on behalf
    of the administrator and may not be all satisfying because the
    standard 2.2.19 kernel does not contain some of the drivers that
    are included in the SuSE kernel (ppp over ethernet, hardware health
    monitoring (SMBus), reiserfs, graphics hardware acceleration
    modules (DRI), ...).

  Recommended solution:

    SuSE have chosen to provide update packages for the supported
    distributions to the newest kernels instead of supplying patched
    update kernel packages of the same kernel version in order to
    avoid confusion about whether a vulnerable version of a kernel
    is installed on a system or not. In addition to the clarifying
    effect of a visible new kernel version that is known to have all
    publically known security problems fixed, SAP LinuxLab
    (http://www.sap.com/linux/) have certified this release of the
    SuSE-enhanced Linux kernel version 2.2.19 with respect to stability
    and performance. We expect that our usership will benefit from this

    Currently, only kernel update packages for the Intel i386 distributions
    are available. The other supported architectures will have their kernel
    updates in their respective update directories on our ftp server.

    The SuSE Linux distribution 6.0 was shipped with a kernel of version 2.0.
    All of the SuSE Linux distributions 6.1, 6.2, 6.3, 6.4, 7.0 and 7.1
    are ready for a kernel of version 2.2.19. However, since update support
    for the SuSE Linux distributions 6.0, 6.1 and 6.2 has been discontinued,
    we strongly encourage all users of these distributions to update their
    systems to a newer version of the SuSE Linux distribution. Please know
    that the full distribution can be installed from our ftp server or one
    of its mirrors. Experienced Linux users may choose to update their kernels
    by hand to the latest version 2.2.19.

  Step-By-Step Installation Instructions:

    The kernel of a Linux/Un*x system is the most critical component with
    relation to stability, reliability and security. By consequence, an
    update of that component requires some care and full attention to
    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, you decide
    if the paragraph is needed for you or not. Please read through all
    of the steps down to the end. 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 to be successfully completed.

  **** Step 1: Determine the needed RPM package

    Use the command
        rpm -qf `awk -F= '/image/{print $2}' < /etc/lilo.conf`
    to find the name of the kernel RPM package that is installed on
    your system. Get the respective kernel RPM package from the following
    where  is the distribution version of your system (one out of
    6.3, 6.4, 7.0 or 7.1).
    Most installations are likely to run a k_deflt kernel.
    To verify the integrity of the files that you need to download, see the
    section "Verification" near the end of this announcement.

    In SuSE-6.3 distributions, the above command can produce inconclusive
    results. This is caused by a different kernel installation procedure
    in this version of the SuSE Linux distribution.
    To select your kernel type, choose from the following options:
    k_eide  - should be used for "exotic" IDE chipsets, mostly found on
              additional IDE interface adapters to PCI or ISA bus systems.
    k_laptop - should be used for laptops. This kernel has APM support
    k_i386  - a kernel that should run on most i386 processors. Use this
              kernel package if the k_pentiu kernel will not boot.
    k_smp   - kernel for multiprocessor systems (SMP)
    k_pentiu - the standard kernel. It should run on most systems.

    In the case that you have a self-compiled kernel running on your
    system, please note that most kernels for the newer distributions
    have APM configured. This obsoletes the need for a particular
    laptop kernel. k_deflt (after SuSE-6.3) should do on most modern

  **** Step 2: SuSE-6.3 special

    If you have a SuSE-6.3 system, continue to read this paragraph,
    otherwise jump to Step 3.
    In SuSE Linux version 6.3, the kernel and the kernel modules are
    packaged in two different packages. Both packages must be downloaded
    and installed. On SMP systems, the packages kernmods (-> kernmod-SMP)
    and k_smp are needed. On single processor systems, get the kernmod
    package plus the package as determined by the description in Step 1.

  **** Step 3: Installation of the RPM package

    Install the rpm package using the command
        rpm -Uhv 
    where  is the rpm package you downloaded in Step 1 (for
    6.3 also Step 2, two packages!).

    If the RPM command complains about conflicting files or unfulfilled
    dependencies, use the options "--nodeps" and "--force". In this case
    there is no risk for the consistency of the packages on your system.

  **** Step 4: aic7xxx

    If you use an Adaptec aic7xxx SCSI host adapter, continue to read
    this paragraph, otherwise jump to Step 5.
    The new kernel comes with two versions for the Adaptec aic7xxx driver.
    If you have such a card, you should see the driver listed in the
    output from the command
    or you should see the adapter in the output of the command
    The new driver is known to work reliably. However, if you encounter
    any problems with CDROM drives or other removeable devices (CD-RW
    drives, tapes, etc) after this kernel upgrade, then you should try to
    use the old driver which is called aic7xxx_old instead of aic7xxx.
    If you decide to make this change, then the steps 6 and 7 are
    mandatory for the update to succeed, regardless if you get back to
    this paragraph after your first reboot or not.
    To use the old driver, please use your favourite editor to edit
    the file /etc/rc.config. Change aic7xxx into aic7xxx_old at the line
    that starts with INITRD_MODULES. You should find it near the top of the
    file. Do not forget to save your changes. Then go to Steps 6 and 7.

    If you want to use the new driver, then do not change anything.

  **** Step 5: LVM

    If you use LVM, then continue to read this paragraph,
    otherwise jump to Step 6.
    If you use LVM (Logical Volume Manager) in your installation of SuSE
    Linux, then you need the updated lvm package from the kernel/2.2.19/
    directory for your distribution as well. The package contains the
    userspace utilities to manage the Logical Volume Manager driver.
    An update package is needed because the LVM data format/structure on
    disk has changed with the new version of the LVM kernel driver.
    Install the package as usual using the command
        rpm -Uhv lvm-0.9.1_beta4-12.i386.rpm
    Be sure you have downloaded the package for the explicit version
    of your SuSE Linux Installation. The package names are identical
    for all distribution versions.
    WARNING: After the first boot with the new kernel you will not be able
    to downgrade to older versions of LVM any more.

  **** Step 6: initrd

    Upon kernel boot (after lilo runs), the kernel needs to use the
    drivers for the device (disk/raid) where the root filesystem
    is located. If this driver is not compiled into the kernel, it is
    supplied as a kernel module that must be loaded _before_ the
    root filesystem is mounted. This is done using a ramdisk that is
    loaded along with the kernel by lilo (See next Step).
    This ramdisk, called "initrd", must be generated using the command
    The modules as configured in the variable INITRD_MODULES from
    /etc/rc.config (See Step 4) are being added to the initrd.
    Without the "mk_initrd"-call your system might not boot any more.

  **** Step 7: lilo

    lilo is responsible for loading the kernel image and the initrd
    ramdisk image into the system and for transferring control over the
    system to the kernel. Therefore, a proper installation of the
    bootloader (by calling the program lilo) is essential for the
    system to boot (!).
    Manually changed settings in /etc/lilo.conf require the admin to make
    sure that /boot/vmlinuz is listed in the first "image" line in that
    file. Verify that the line starting with initrd= is set to
    and you should see your label in an output like
      Added linux *
    Every other output should be considered an error and requires
    attention. If your system managed to reboot before the upgrade, you
    should not see any additional output from lilo at this stage.

  **** Step 8: SuSE-7.0 special

    If you have a SuSE Linux 7.0 distribution, then continue to read this
    paragraph, otherwise jump to Step 9.
    During testing of the 2.2.19-SuSE Linux kernel, we have found an error
    in the glibc (shlibs) package of the SuSE Linux 7.0 distribution. The
    error might result in readdir(3) calls to return -EIO to the user
    program due to incorrect handling of the return value of getdents(2)
    from the kernel. This bug mostly appears on NFS-mounted filesystems
    when commands such as tar(1) are used.
    We have prepared update packages that solve this specific problem.
    Former security updates are included in this package, of course.

    Determine which packages you need: See the output of the command
        rpm -q shlibs libc libd nssv1
    It should not be necessary to update a package that is not installed.
    Select the needed update packages and download them from the following
    list of URLs

          !!!           !!!     WARNING:     !!!            !!!
    After download and before installation of the glibc packages, the
    system should be brought to single user mode ("init 1"). If this
    is not suitable for operational reasons, then please keep the system
    as calm as at all possible during the update of the shlibs and nssv1
    packages. In particular, do not run any shell scripts or any other
    processes that execute other binaries. Stop the cron and at services,
    and shut down your MTA. Suspend the execution of active processes
    by killing them with the -STOP signal and let them resume their work
    after the installation of the shlibs and nssv1 packages with a -CONT
    After verifying that the right conditions are in place, install the
    packages using the command
        rpm -Fhv nssv*.rpm shlibs*.rpm
        rpm -Fhv 
    Afterwards, execute the command
    to update the cache for the dynamic linker.

    NOTE: updating shared libraries in the running system requires enough
    space on the root and /usr filesystem to keep both versions of the
    shared libraries on the disk. The old libraries will be deleted, but
    the files continue to use diskspace until they are not used by any
    processes any more. (See Step 9). Similar considerations apply for the
    the memory consumption of the system.

  **** Step 9: reboot

    Reboot your machine for the new kernel to boot and therefore become
    active. Make sure that all of the above steps have completed
    successfully. Shutdown and reboot using the command
        shutdown -r now
        init 6

    a)  After the upgrade, you might notice kernel messages upon execution
        of an NFS mount command:
          silence kernel: nfs warning: mount version older than kernel
        These messages are complaints that the mount(8) command needs to
        be upgraded. The mount(8) command is contained in the package
        "util" ("util-linux" for SuSE-7.1) - we will provide update
        packages for the "util" ("util-linux" for SuSE-7.1) package.
        The change is mostly a cosmetic nature and does not have any
        impact on the security or the stability of the system.

    b)  The kernel sources are contained in the RPM
        kernel/2.2.19/lx_sus22-2.2.19.SuSE-25.i386.rpm in each distribution
        update tree. The kernel documentation is in the package
        kernel/2.2.19/lx_doc22-2.2.19.SuSE-25.i386.rpm and installs to the
        base path /usr/share/doc/kernel/.

    c)  The directory kernel/misc/ in each distribution tree contains
        the .config files, the spec and changes file as well as the
        compilation output for the respective kernel, each in a directory
        where it belongs to. In addition, the sources for the lvm
        package can be found in the lvm directory as appropriate.

  Known problems:

    * The kernel modules for the cipe and the freeswan packages are not
      contained in the kernel RPM packages. If you use these packages, then
      you should wait with the kernel update until the kernel modules
      for these packages are available, or you could recompile the kernel
      modules yourself (See section Notes b). Please read the section 2)
      of the upcoming SuSE security announcements for the location of the
      cipecb.o and ipsec.o kernel modules.


    All RPM packages are gpg-signed using the build@suse.de SuSE packaging
    key that can be found in the toplevel directory of the first CD on
    SuSE-7.1 and younger, as well as at
    ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de (this key is signed
    by security@suse.de).
    All files that are needed or referred to in this announcement have
    their md5 sums listed in the file
    ftp://ftp.suse.com/pub/suse/i386/update//kernel/MD5SUMS .
    These files are signed by security@suse.de in the file MD5SUMS.sig.
    Since there are 150 files, we do not send the md5sums with the mail
    this time.


2)  Acknowledgements

    SuSE Security wishes to express their gratitude for the following people
    who have invested their time for the bugs that are subject of this

    Chris Evans
    Solar Designer
    Alan Cox
    David Miller for spotting and fixing the problems as listed in the
        2.2.19 release notes
    Chris Mason for fixing the reiserfs mmap/write race condition
    Sven Berkvens and Marc Olzheim for spotting the mmap/write race
        condition in FreeBSD drivers that affects reiserfs in Linux


3)  standard appendix:

    SuSE runs two security mailing lists to which any interested party may

        -   general/linux/SuSE security discussion.
            All SuSE security announcements are sent to this list.
            To subscribe, send an email to

        -   SuSE's announce-only mailing list.
            Only SuSE's security annoucements are sent to this list.
            To subscribe, send an email to

    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.


    The information in this advisory may be distributed or reproduced,
    provided that the advisory is not modified in any way.
    SuSE GmbH makes no warranties of any kind whatsoever with respect
    to the information contained in this security advisory.