RHSA-2010:0439 - Security Advisory

Topic

Updated kernel packages that fix one security issue and two bugs are now
available for Red Hat Enterprise Linux 5.3 Extended Update Support.

The Red Hat Security Response Team has rated this update as having
important security impact. A Common Vulnerability Scoring System (CVSS)
base score, which gives a detailed severity rating, is available from the
CVE link in the References section.

Description

The kernel packages contain the Linux kernel, the core of any Linux
operating system.

This update fixes the following security issue:

• a use-after-free flaw was found in the tcp_rcv_state_process() function

in the Linux kernel TCP/IP protocol suite implementation. If a system using
IPv6 had the IPV6_RECVPKTINFO option set on a listening socket, a remote
attacker could send an IPv6 packet to that system, causing a kernel panic
(denial of service). (CVE-2010-1188, Important)

This update also fixes the following bugs:

• a memory leak occurred when reading files on an NFS file system that was

mounted with the "noac" option, causing memory to slowly be consumed.
Unmounting the file system did not free the memory. With this update, the
memory is correctly freed, which resolves this issue. (BZ#588221)

• the RHSA-2009:0225 update fixed a bug where, in some cases, on systems

with the kdump service enabled, pressing Alt+SysRq+C to trigger a crash
resulted in a system hang; therefore, the system did not restart and boot
the dump-capture kernel as expected; no vmcore file was logged; and the
following message was displayed on the console:

BUG: warning at arch/[arch]/kernel/crash.c:[xxx]/nmi_shootdown_cpus() (Not
tainted)

The RHSA-2009:0225 update resolved this issue by not calling printk()
during a crash. It was later discovered that this fix did not resolve the
issue in all cases, since there was one condition where printk() was
still being called: at a warning condition inside the mdelay() call.

This update replaces mdelay() calls with udelay(), where such a warning
condition does not exist, which fully resolves this issue, allowing
Alt+SysRq+C to work as expected. (BZ#588211)

Users should upgrade to these updated packages, which contain backported
patches to correct these issues. The system must be rebooted for this
update to take effect.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

To install kernel packages manually, use "rpm -ivh [package]". Do not
use "rpm -Uvh" as that will remove the running kernel binaries from
your system. You may use "rpm -e" to remove old kernels after
determining that the new kernel functions properly on your system.

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 ia64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 5.3 i386
• Red Hat Enterprise Linux Server - AUS 5.3 x86_64
• Red Hat Enterprise Linux Server - AUS 5.3 ia64
• Red Hat Enterprise Linux Server - AUS 5.3 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 5.3 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 5.3 ppc

Fixes

• BZ - 577711 - CVE-2010-1188 kernel: ipv6: skb is unexpectedly freed
• BZ - 588211 - [RHEL5.3 GA] The kernel stalls before starting second kernel when pressing Alt+SysRq+c in graphical console [rhel-5.3.z]
• BZ - 588221 - memory leak when reading from files mounted with nfs mount option 'noac' [rhel-5.3.z]

CVEs

• CVE-2010-1188

References

• http://www.redhat.com/security/updates/classification/#important