Synopsis
Important: kernel-rt security and bug fix update
Type/Severity
Security Advisory: Important
Topic
Updated kernel-rt packages that fix several security issues and three bugs
are now available for Red Hat Enterprise MRG 2.3.
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-rt packages contain the Linux kernel, the core of any Linux
operating system.
This update fixes the following security issues:
- A flaw was found in the way file permission checks for the
"/dev/cpu/[x]/msr" files were performed in restricted root environments
(for example, when using a capability-based security model). A local user
with the ability to write to these files could use this flaw to escalate
their privileges to kernel level, for example, by writing to the
SYSENTER_EIP_MSR register. (CVE-2013-0268, Important)
- A race condition was found in the way the Linux kernel's ptrace
implementation handled PTRACE_SETREGS requests when the debuggee was woken
due to a SIGKILL signal instead of being stopped. A local, unprivileged
user could use this flaw to escalate their privileges. (CVE-2013-0871,
Important)
- An out-of-bounds access flaw was found in the way SOCK_DIAG_BY_FAMILY
Netlink messages were processed in the Linux kernel. A local, unprivileged
user could use this flaw to escalate their privileges. (CVE-2013-1763,
Important)
- It was found that the default SCSI command filter does not accommodate
commands that overlap across device classes. A privileged guest user could
potentially use this flaw to write arbitrary data to a LUN that is
passed-through as read-only. (CVE-2012-4542, Moderate)
- A flaw was found in the way the __skb_recv_datagram() function in the
Linux kernel processed payload-less socket buffers (skb) when the MSG_PEEK
option was requested. A local, unprivileged user could use this flaw to
cause a denial of service (infinite loop). (CVE-2013-0290, Moderate)
The CVE-2012-4542 issue was discovered by Paolo Bonzini of Red Hat.
This update also fixes the following bugs:
- There was high contention on run-queue lock when load balancing before
idling, causing latency spikes on high CPU core count systems. With this
update, IPI is used to send notification to cores with pending work, and
the cores push the work rather than trying to pull it, resolving this
issue. (BZ#858396)
- Previously, ACPI lock was converted to an rt_mutex, leading to a
traceback when scheduling while atomic. With this update, ACPI lock has
been converted back to a raw spinlock. (BZ#909965)
- Fibre Channel (FC)/iSCSI device state was set to off-line and after a
timeout, not set back to running. Such a device would not come back online
after a fast_io_fail or timeout. With this update, an explicit check for
the device being offline has been added, and the device is set back to
running when re-initializing, allowing devices to recover after a failure
or timeout. (BZ#912942)
Users should upgrade to these updated packages, which 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
Fixes
- BZ - 858396 - latency issues on four-socket systems
- BZ - 875360 - CVE-2012-4542 kernel: block: default SCSI command filter does not accomodate commands overlap across device classes
- BZ - 908693 - CVE-2013-0268 kernel: x86/msr: /dev/cpu/*/msr local privilege escalation
- BZ - 911473 - CVE-2013-0290 kernel: net: infinite loop in __skb_recv_datagram()
- BZ - 911937 - CVE-2013-0871 kernel: race condition with PTRACE_SETREGS
- BZ - 915052 - CVE-2013-1763 kernel: sock_diag: out-of-bounds access to sock_diag_handlers[]
CVEs
References
Vulmon