RHBA-2012:1104 - Bug Fix Advisory

Topic

Updated kernel packages that fix four bugs are now available for Red Hat
Enterprise Linux 6.

Description

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

This update fixes the following bugs:

• Previously, futex operations on read-only (RO) memory maps did not work

correctly. This broke workloads that had one or more reader processes performing
the FUTEX_WAIT operation on a futex within a read-only shared file mapping and a
writer process that had a writable mapping performing the FUTEX_WAKE operation.
With this update, the FUTEX_WAKE operation is performed with a RO MAP_PRIVATE
mapping, and is successfully awaken if another process updates the region of the
underlying mapped file. (BZ#836904)

• When removing a bonding module, the bonding driver uses code separate from the

net device operations to clean up the VLAN code. Recent changes to the kernel
introduced a bug which caused a kernel panic if the vlan module was removed
after the bonding module had been removed. To fix this problem, the VLAN group
removal operations found in the bonding kill_vid path are now duplicated in
alternate paths which are used when removing a bonding module. (BZ#837218)

• The bonding method for adding VLAN Identifiers (VIDs) did not always add the

VID to a slave VLAN group. When the NETIF_F_HW_VLAN_FILTER flag was not set on a
slave, the bonding module could not add new VIDs to it. This could cause
networking problems and the system to be unreachable even if NIC messages did
not indicate any problems. This update changes the bond VID add path to always
add a new VID to the slaves (if the VID does not exist). This ensures that
networking problems no longer occur in this scenario. (BZ#837227)

• Previously, reference counting was imbalanced in the slave add and remove

paths for bonding. If a network interface controller (NIC) did not support the
NETIF_F_HW_VLAN_FILTER flag, the bond_add_vlans_on_slave() and
bond_del_vlans_on_slave() functions did not work properly, which could lead to a
kernel panic if the VLAN module was removed while running. The underlying source
code for adding and removing a slave and a VLAN has been revised and now also
contains a common path, so that kernel crashes no kernel no longer occur in the
described scenario. (BZ#837843)

All users of kernel are advised to upgrade to these updated packages, which fix
these bugs. 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
https://access.redhat.com/knowledge/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.3 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.3 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.3 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 6 i386
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.3 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 837227 - 6.3 regression in bnx2 driver when used in bond [rhel-6.3.z]

CVEs

(none)

References

(none)