RHSA-2012:1042 - Security Advisory

Topic

Updated kernel packages that fix various security issues and three bugs are
now available for Red Hat Enterprise Linux 6.1 Extended Update Support.

The Red Hat Security Response Team has rated this update as having
important security impact. Common Vulnerability Scoring System (CVSS) base
scores, which give detailed severity ratings, are available for each
vulnerability from the CVE links 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 issues:

• A local, unprivileged user could use an integer overflow flaw in

drm_mode_dirtyfb_ioctl() to cause a denial of service or escalate their
privileges. (CVE-2012-0044, Important)

• It was found that the kvm_vm_ioctl_assign_device() function in the KVM

(Kernel-based Virtual Machine) subsystem of a Linux kernel did not check if
the user requesting device assignment was privileged or not. A local,
unprivileged user on the host could assign unused PCI devices, or even
devices that were in use and whose resources were not properly claimed by
the respective drivers, which could result in the host crashing.
(CVE-2011-4347, Moderate)

• A flaw was found in the way the Linux kernel's XFS file system

implementation handled on-disk Access Control Lists (ACLs). A local,
unprivileged user could use this flaw to cause a denial of service or
escalate their privileges by mounting a specially-crafted disk.
(CVE-2012-0038, Moderate)

• It was found that the Linux kernel's register set (regset) common

infrastructure implementation did not check if the required get and set
handlers were initialized. A local, unprivileged user could use this flaw
to cause a denial of service by performing a register set operation with a
ptrace() PTRACE_SETREGSET or PTRACE_GETREGSET request. (CVE-2012-1097,
Moderate)

• A race condition was found in the Linux kernel's memory management

subsystem in the way pmd_none_or_clear_bad(), when called with mmap_sem in
read mode, and Transparent Huge Pages (THP) page faults interacted. A
privileged user in a KVM guest with the ballooning functionality enabled
could potentially use this flaw to crash the host. A local, unprivileged
user could use this flaw to crash the system. (CVE-2012-1179, Moderate)

Red Hat would like to thank Chen Haogang for reporting CVE-2012-0044; Sasha
Levin for reporting CVE-2011-4347; Wang Xi for reporting CVE-2012-0038; and
H. Peter Anvin for reporting CVE-2012-1097.

This update also fixes the following bugs:

• When a RoCE (RDMA over Converged Ethernet) adapter with active RoCE

communications was taken down suddenly (either by adapter failure or the
intentional shutdown of the interface), the ongoing RoCE communications
could cause the kernel to panic and render the machine unusable. A patch
has been provided to protect the kernel in this situation and to pass an
error up to the application still using the interface after it has been
taken down instead. (BZ#799944)

• The fix for Red Hat Bugzilla bug 713494, released via RHSA-2011:0928,

introduced a regression. Attempting to change the state of certain
features, such as GRO (Generic Receive Offload) or TSO (TCP segment
offloading), for a 10 Gigabit Ethernet card that is being used in a
virtual LAN (VLAN) resulted in a kernel panic. (BZ#816974)

• If a new file was created on a Network File System version 4 (NFSv4)

share, the ownership was set to nfsnobody (-2) until it was possible to
upcall to the idmapper. As a consequence, subsequent file system operations
could incorrectly use "-2" for the user and group IDs for the given file,
causing certain operations to fail. In reported cases, this issue also
caused "Viminfo file is not writable" errors for users running Vim with
files on an NFSv4 share. (BZ#820960)

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
https://access.redhat.com/knowledge/articles/11258

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 6.1 x86_64
• Red Hat Enterprise Linux for x86_64 - Extended Update Support 6.1 i386
• Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.1 s390x
• Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.1 ppc64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1 x86_64
• Red Hat Enterprise Linux Server - Extended Update Support from RHUI 6.1 i386
• Red Hat Virtual Storage Appliance (from RHUI) 6.1 x86_64

Fixes

• BZ - 756084 - CVE-2011-4347 kernel: kvm: device assignment DoS
• BZ - 772894 - CVE-2012-0044 kernel: drm: integer overflow in drm_mode_dirtyfb_ioctl()
• BZ - 773280 - CVE-2012-0038 kernel: xfs heap overflow
• BZ - 799209 - CVE-2012-1097 kernel: regset: Prevent null pointer reference on readonly regsets
• BZ - 803793 - CVE-2012-1179 kernel: thp:__split_huge_page() mapcount != page_mapcount BUG_ON()

CVEs

• CVE-2011-4347
• CVE-2012-0038
• CVE-2012-0044
• CVE-2012-1097
• CVE-2012-1179

References

• https://access.redhat.com/security/updates/classification/#important
• https://rhn.redhat.com/errata/RHSA-2011-0928.html