FreeBSD 4.6-RELEASE/4.6.2-RELEASE Errata

The FreeBSD Project

$FreeBSD: src/release/doc/en_US.ISO8859-1/errata/article.sgml,v 2002/09/16 23:08:45 bmah Exp $

This document lists errata items for FreeBSD 4.6-RELEASE, containing significant information discovered after the release. This information includes security advisories, as well as news relating to the software or documentation that could affect its operation or usability. An up-to-date version of this document should always be consulted before installing this version of FreeBSD.

Unless otherwise noted, items listed here also pertain to FreeBSD 4.6.2-RELEASE, which was designed to fix certain, specific problems in 4.6-RELEASE (see the release notes for more details).

This errata document for FreeBSD 4.6-RELEASE will be maintained until the release of FreeBSD 4.7-RELEASE.

1 Introduction

This errata document contains ``late-breaking news'' about FreeBSD 4.6-RELEASE. Before installing this version, it is important to consult this document to learn about any post-release discoveries or problems that may already have been found and fixed.

Any version of this errata document actually distributed with the release (for example, on a CDROM distribution) will be out of date by definition, but other copies are kept updated on the Internet and should be consulted as the ``current errata'' for this release. These other copies of the errata are located at, plus any sites which keep up-to-date mirrors of this location.

Source and binary snapshots of FreeBSD 4-STABLE also contain up-to-date copies of this document (as of the time of the snapshot).

For a list of all FreeBSD CERT security advisories, see or

2 Security Advisories

FreeBSD 4.6-RELEASE contains a fix for a bug described in security advisory SA-02:23 (which addressed the use of file descriptors by set-user-id or set-group-id programs). An error has been discovered in the bugfix; it is still possible for systems using procfs(5) or linprocfs(5) to be exploited. A revised version of security advisory FreeBSD-SA-02:23 contains a corrected bugfix. This problem was corrected in FreeBSD 4.6.2-RELEASE.

A buffer overflow in the resolver could be exploited by a malicious domain name server or an attacker forging DNS messages. This could potentially be used to force arbitrary code to run on a client machine with the privileges of a resolver-using application. See security advisory FreeBSD-SA-02:28 for more information and a fix. This problem was corrected in FreeBSD 4.6.2-RELEASE.

Badly-formed NFS packets could trigger a buffer overflow in tcpdump(1). For a fix to this problem, see security advisory FreeBSD-SA-02:29. This problem was corrected in FreeBSD 4.6.2-RELEASE.

ktrace(1) can be used to trace the operation of formerly-privileged processes. This is undesirable, as it is then possible to leak information obtained while these processes had elevated privileges. See security advisory FreeBSD-SA-02:30 for a workaround and a fix. This problem was corrected in FreeBSD 4.6.2-RELEASE.

A race condition in pppd(8) can be used to change the permissions of an arbitrary file. For more details, a workaround, and bugfix information, see security advisory FreeBSD-SA-02:32. This problem was corrected in FreeBSD 4.6.2-RELEASE.

Multiple buffer overflows have been discovered in OpenSSL. More details (including workarounds and bugfixes) can be found in security advisory FreeBSD-SA-02:33. This problem was corrected in FreeBSD 4.6.2-RELEASE.

A bug in the XDR decoder (used by Sun RPC) could result in a heap buffer overflow. Security advisory FreeBSD-SA-02:34 contains workaround and bugfix information. This problem was corrected in FreeBSD 4.6.2-RELEASE.

Local users can, under certain circumstances, read and write arbitrary blocks on an FFS filesystem has been corrected. More details can be found in security advisory FreeBSD-SA-02:35, which contains a workaround and bugfix information. This problem was corrected in FreeBSD 4.6.2-RELEASE.

A bug in the NFS server code could allow a remote denial of service attack. Security advisory FreeBSD-SA-02:36 has information on a fix and a workaround. This problem was corrected in FreeBSD 4.6.2-RELEASE.

A bug in kqueue(2) could allow local users to panic a system. Correction information is contained in security advisory FreeBSD-SA-02:37. This problem was corrected in FreeBSD 4.6.2-RELEASE.

Several bounds-checking bugs in system calls could result in some system calls returning a large portion of kernel memory. More details can be found in security advisory FreeBSD-SA-02:38. This problem was corrected in time for FreeBSD 4.6.2-RELEASE, although not mentioned in the accompanying release documentation.

A bug in libkvm could result in some applications leaking file descriptors with access to potentially sensitive information. More details, as well as a bugfix and a workaround, can be found in security advisory FreeBSD-SA-02:39.

3 Late-Breaking News

In FreeBSD 4.6-RELEASE, the default maximum TCP window size was lowered from 65536 bytes to 57334 bytes, for better compatability with some versions of IPFilter.

A recently-discovered interaction between the FreeBSD kernel and the archivers/zip port can result in some errors on the alpha platform. A post-release fix has been committed to the FreeBSD ports tree; versions of the archivers/zip port beginning with 2.3_1 will function correctly.

On the alpha platform, the de(4) and txp(4) drivers were moved from the boot kernel on the floppy images to modules on the mfsroot floppy. This change was made in order to get the alpha kernel to fit onto the boot floppy. It should be transparent to all users, as sysinstall(8) will automatically load any kernel modules it finds on the mfsroot floppy.

Several last-minute patches were made to the x11-servers/XFree86-4-Server package. These allow the various server configuration programs to give better support for the sysmouse device supported by moused(8). The binary packages on the CDROMs and the FTP sites incoporate this patch and bear the version number 4.2.0_3. However, the ports collection included in the distribution does not contain this patch. To get an updated version, use CVSup to obtain a more recent ports collection.

Some FreeBSD/i386 users have experienced difficulties reading from certain ATA CDROM drives. Specific models on which this problem has been observed include the AOpen 48x, 52x, and 56x CDROM drives, as well as the Mitsumi Slim CRMC-SR242S CDROM drive. A typical symptom is the following error message on the console and/or dmesg(8) buffer (sometimes accompanied by a kernel panic):

    acd0: READ_BIG command timeout - resetting
    ata1: resetting devices .. done

In some cases, this bug can prevent installation of FreeBSD from an affected CDROM drive. It can cause sysinstall(8) to hang while extracting distribution files from CD media.

A two-part workaround listed here has shown to be helpful in some (but not necessarily all) cases. First, to allow a CDROM installation, it is necessary to modify the normal CDROM installation procedure:

  1. Start the computer with a FreeBSD installation CDROM in the drive.

  2. Wait for a console message similar to:

        Hit [Enter] to boot immediately, or any other key for command prompt.
        Booting [kernel] in 9 seconds...
  3. Immediately interrupt the boot process by pressing the Space bar on the keyboard.

  4. Enter the following three lines at the ok prompt:

        ok set hw.ata.ata_dma="1"
        ok set hw.ata.atapi_dma="1"
        ok boot
  5. Continue the installation as normal.

The second part of the workaround takes place after completing the CDROM installation (or a successful source upgrade). It consists of configuring the ata(4) driver so that future CDROM reads work correctly:

  1. Add the following two lines to /boot/loader.conf (creating this file if it does not already exist):

  2. Reboot the machine.

This problem was fixed in FreeBSD 4.7-PRERELEASE on 31 July 2002, as well as FreeBSD 4.6.2-RELEASE.

Due to a bug in the release generation process, some of the directories under /usr/share/examples are empty (most notably /usr/share/examples/cvsup). A partial workaround is to install the sshare distribution via sysinstall(8) (from the main menu, choose Configure, Distributions, src, then share). /usr/src/share/examples will then contain the missing files. This problem was corrected in FreeBSD 4.7-PRERELEASE on 16 July 2002, as well as FreeBSD 4.6.2-RELEASE.

The item in the ``Filesystems'' section of the release notes contains a small grammatical error. It should read: ``A bug has been fixed in soft updates that could cause occasional filesystem corruption if the system is shut down immediately after performing heavy filesystem activities, such as installing a new kernel or other software.''

Due to an omission, pkg_add -r on 4.6-RELEASE or 4.6.2-RELEASE may attempt to fetch packages built for FreeBSD -STABLE, rather than for the appropriate release. As a workaround, set the PACKAGESITE environment variable appropriately before invoking pkg_add(1). For example, a csh(1) user on 4.6.2-RELEASE could use:

    % setenv PACKAGESITE \

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