FreeBSD 5.2-RELEASE Errata

1 Introduction

This errata document contains ``late-breaking news'' about FreeBSD 5.2-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version of this errata document actually distributed with the release (for example, on a CDROM distribution) will be out of date by definition, but other copies are kept updated on the Internet and should be consulted as the ``current errata'' for this release.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 http://www.FreeBSD.org/releases/, plus any sites which keep up-to-date mirrors of this location.

Source and binary snapshots of FreeBSD 5-CURRENT 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 http://www.FreeBSD.org/security/ or ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/.

2 Security Advisories

(30 Jan 2004, updated 28 Feb 2004) A bug in mksnap_ffs(8) causes the creation of a filesystem snapshot to reset the flags on the filesystem to their default values. The possible consequences depend on local usage, but can include disabling extended access control lists or enabling the use of setuid executables stored on an untrusted filesystem. This bug also affects the dump(8) -L option, which uses mksnap_ffs(8). Note that mksnap_ffs(8) is normally only available to the superuser and members of the operator group. This bug has been fixed on the FreeBSD 5.2-RELEASE security fix branch and in FreeBSD 5.2.1-RELEASE. For more information, see security advisory FreeBSD-SA-04:01.

(8 Feb 2004, updated 28 Feb 2004) A bug with the System V Shared Memory interface (specifically the shmat(2) system call) can cause a shared memory segment to reference unallocated kernel memory. In turn, this can permit a local attacker to gain unauthorized access to parts of kernel memory, possibly resulting in disclosure of sensitive information, bypass of access control mechanisms, or privilege escalation. This bug has been fixed on the FreeBSD 5.2-RELEASE security fix branch and in FreeBSD 5.2.1-RELEASE. More details, including bugfix and workaround information, can be found in security advisory FreeBSD-SA-04:02.

(28 Feb 2004) It is possible, under some circumstances, for a processor with superuser privileges inside a jail(8) environment to change its root directory to a different jail, giving it read and write access to the files and directories within. This vulnerability has been closed on the FreeBSD 5.2-RELEASE security fix branch and in FreeBSD 5.2.1-RELEASE. Information on the bug fix can be found in security advisory FreeBSD-SA-04:03.

(4 Mar 2004) It is possible for a remote attacker to conduct a low-bandwidth denial-of-service attack against a machine providing TCP-based services, filling up the target's memory buffers and potentially leading to a system crash. This vulnerability has been addressed on the FreeBSD 5.2-RELEASE security fix branch, but is present in both FreeBSD 5.2-RELEASE and 5.2.1-RELEASE. Security advisory FreeBSD-SA-04:04 contains more details, as well as information on patching existing systems.

(17 Mar 2004) By performing a specially crafted SSL/TLS handshake with an application that uses OpenSSL a null pointer may be dereferenced. This may in turn cause the application to crash, resulting in a denial of service attack. For more information see the Security Advisory FreeBSD-SA-04:05 which contains more details and instructions on how to patch existing systems.

(29 Mar 2004) A local attacker may take advantage of a programming error in the handling of certain IPv6 socket options in the setsockopt(2) system call to read portions of kernel memory without proper authorization. This may result in disclosure of sensitive data, or potentially cause a panic. See Security Advisory FreeBSD-SA-04:06 for a more detailed description and instructions on how to patch existing systems.

3 Open Issues

(9 Jan 2004) Due to a change in cpp(1) behavior, the login screen for xdm(1) is in black and white, even on systems with color displays. As a workaround, update to a newer version of the x11/XFree86-4-clients port/package.

(9 Jan 2004) There remain some residual problems with ACPI. In some cases, systems may behave erratically, or hang at boot time. As a workaround, disable ACPI, using the ``safe mode'' option of the bootloader or using the hint.acpi.0.disabled kernel environment variable. These problems are being investigated. For problems that have not already been reported (check the mailing list archives before posting), sending the output of dmesg(8) and acpidump(8) to the FreeBSD-CURRENT mailing list may help diagnose the problem.

(9 Jan 2004, updated 28 Feb 2004) In some cases, ATA devices may behave erratically, particularly SATA devices. Reported symptoms include command timeouts or missing interrupts. These problems appear to be timing-dependent, making them rather difficult to isolate. Workarounds include:

• Turn off ATA DMA using the ``safe mode'' option of the bootloader or the hw.ata.ata_dma sysctl variable.

• Use the host's BIOS setup options to put the ATA controller in its ``legacy mode'', if available.

• Disable ACPI, for example using the ``safe mode'' option of the bootloader or using the hint.acpi.0.disabled kernel environment variable.

Some of these problems were addressed in FreeBSD 5.2.1-RELEASE with the import of a newer ata(4) from 5.2-CURRENT.

(9 Jan 2004) Installing over NFS when using the install floppies requires that the nfsclient.ko module be manually loaded from the third floppy disk. This can be done by following the prompts when sysinstall(8) launches to load a driver off of the third floppy disk.

(9 Jan 2004) The use of multiple vchans (virtual audio channels with dynamic mixing in software) in the pcm(4) driver has been known to cause some instability.

(10 Jan 2004) Although APIC interrupt routing seems to work correctly on many systems, on some others (such as some laptops) it can cause various errors, such as ata(4) errors or hangs when starting or exiting X11. For these situations, it may be advisable to disable APIC routing, using the ``safe mode'' of the bootloader or the hint.apic.0.disabled loader tunable. Note that disabling APIC is not compatible with SMP systems.

(10 Jan 2004, updated 28 Feb 2004) The NFSv4 client may panic when attempting an NFSv4 operation against an NFSv3/NFSv2-only server. This problem has been fixed with revision 1.4 of src/sys/rpc/rpcclnt.c in FreeBSD 5.2-CURRENT. It was also fixed in FreeBSD 5.2.1-RELEASE.

(11 Jan 2004, updated 28 Feb 2004) Some problems have been encountered when using third-party NSS modules, such as nss_ldap, and groups with large membership lists. These have been fixed with revision 1.2 of src/include/nss.h and revision 1.2 of src/lib/libc/net/nss_compat.c in FreeBSD 5.2-CURRENT; this fix was backported to FreeBSD 5.2.1-RELEASE.

(13 Jan 2004) The FreeBSD 5.2-CURRENT release notes incorrectly stated that GCC was a post-release GCC 3.3.3 snapshot. They should have stated that GCC was a pre-release GCC 3.3.3 snapshot.

(13 Jan 2004, updated 28 Feb 2004) The sysutils/kdeadmin3 port/package has a bug in the KUser component that can cause deletion of the root user from the system password file. Users are strongly urged to upgrade to version 3.1.4_1 of this port/package. The package set included with FreeBSD 5.2.1-RELEASE contains the fixed version of this package.

(21 Jan 2004, updated 28 Feb 2004) Some bugs in the IPsec implementation imported from the KAME Project can result in memory objects being freed before all references to them were removed. Reported symptoms include erratic behavior or kernel panics after flushing the Security Policy Database (SPD). Some of these problems have been fixed in FreeBSD 5.2-CURRENT in rev. 1.31 of src/sys/netinet6/ipsec.c, rev. 1.136 of src/sys/netinet/in_pcb.c, and revs. 1.63 and 1.64 of src/sys/netkey/key.c. These bugfixes were backported to FreeBSD 5.2.1-RELEASE. More information about these problems has been posted to the FreeBSD-CURRENT mailing list, in particular the thread entitled ``[PATCH] IPSec fixes''.

(28 Feb 2004) The edition of the Porters Handbook included with FreeBSD 5.2.1-RELEASE contained an incorrect value for 5.2.1-RELEASE's __FreeBSD_version. The correct value is 502010.

4 Late-Breaking News

(10 Jan 2004, updated 28 Feb 2004) The TCP implementation in FreeBSD now includes protection against a certain class of TCP MSS resource exhaustion attacks, in the form of limits on the size and rate of TCP segments. The first limit sets the minimum allowed maximum TCP segment size, and is controlled by the net.inet.tcp.minmss sysctl variable (the default value is 216 bytes). The second limit is set by the net.inet.tcp.minmssoverload variable, and controls the maximum rate of connections whose average segment size is less than net.inet.tcp.minmss. Connections exceeding this packet rate are reset and dropped. Because this feature was added late in the 5.2-RELEASE release cycle, connection rate limiting is disabled by default, but can be enabled manually by assigning a non-zero value to net.inet.tcp.minmssoverload. This feature was added to FreeBSD 5.2-RELEASE too late for inclusion in its release notes.