Moderate: kernel (SL5)

Synopsis: Moderate: kernel security and bug fix update
Issue Date: 2012-07-10
CVE Numbers: CVE-2012-3375

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

Security fix:

* The fix for CVE-2011-1083 (RHSA-2012:0150) introduced a flaw in the way
the Linux kernel’s Event Poll (epoll) subsystem handled resource clean up
when an ELOOP error code was returned. A local, unprivileged user could use
this flaw to cause a denial of service. (CVE-2012-3375, Moderate)

Bug fixes:

* The qla2xxx driver handled interrupts for QLogic Fibre Channel adapters
incorrectly due to a bug in a test condition for MSI-X support. This update
corrects the bug and qla2xxx now handles interrupts as expected.

* A process scheduler did not handle RPC priority wait queues correctly.
Consequently, the process scheduler failed to wake up all scheduled tasks
as expected after RPC timeout, which caused the system to become
unresponsive and could significantly decrease system performance. This
update modifies the process scheduler to handle RPC priority wait queues as
expected. All scheduled tasks are now properly woken up after RPC timeout
and the system behaves as expected.

* The kernel version 2.6.18-308.4.1.el5 contained several bugs which led to
an overrun of the NFS server page array. Consequently, any attempt to
connect an NFS client running on Enterprise Linux 5.8 to the NFS
server running on the system with this kernel caused the NFS server to
terminate unexpectedly and the kernel to panic. This update corrects the
bugs causing NFS page array overruns and the kernel no longer crashes in
this scenario.

* An insufficiently designed calculation in the CPU accelerator in the
previous kernel caused an arithmetic overflow in the sched_clock() function
when system uptime exceeded 208.5 days. This overflow led to a kernel panic
on the systems using the Time Stamp Counter (TSC) or Virtual Machine
Interface (VMI) clock source. This update corrects the calculation so that
this arithmetic overflow and kernel panic can no longer occur under these

Note: This advisory does not include a fix for this bug for the 32-bit

* Under memory pressure, memory pages that are still a part of a
checkpointing transaction can be invalidated. However, when the pages were
invalidated, the journal head was re-filed onto the transactions’ “forget”
list, which caused the current running transaction’s block to be modified.
As a result, block accounting was not properly performed on that modified
block because it appeared to have already been modified due to the journal
head being re-filed. This could trigger an assertion failure in the
“journal_commit_transaction()” function on the system. The “b_modified”
flag is now cleared before the journal head is filed onto any transaction;
assertion failures no longer occur.

* When running more than 30 instances of the cclengine utility concurrently
on IBM System z with IBM Communications Controller for Linux, the system
could become unresponsive. This was caused by a missing wake_up() function
call in the qeth_release_buffer() function in the QETH network device
driver. This update adds the missing wake_up() function call and the system
now responds as expected in this scenario.

* Recent changes removing support for the Flow Director from the ixgbe
driver introduced bugs that caused the RSS (Receive Side Scaling)
functionality to stop working correctly on Intel 82599EB 10 Gigabit
Ethernet network devices. This update corrects the return code in the
ixgbe_cache_ring_fdir function and setting of the registers that control
the RSS redirection table. Also, obsolete code related to Flow Director
support has been removed. The RSS functionality now works as expected on
these devices.

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.


– Scientific Linux Development Team