Synopsis

Important: kernel-rt security, bug fix, and enhancement update

Type/Severity

Security Advisory: Important

Topic

Updated kernel-rt packages that fix two security issues, several bugs, and
add various enhancements are now available for Red Hat Enterprise MRG 2.5.

Red Hat Product Security 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.

• It was found that the Linux kernel's keys subsystem did not correctly
  garbage collect uninstantiated keyrings. A local attacker could use this
  flaw to crash the system or, potentially, escalate their privileges on the
  system. (CVE-2015-7872, Important)
  
• A flaw was found in the way the Linux kernel handled IRET faults during
  the processing of NMIs. An unprivileged, local user could use this flaw to
  crash the system or, potentially (although highly unlikely), escalate their
  privileges on the system. (CVE-2015-5157, Moderate)
  

This update provides a build of the kernel-rt package for Red Hat
Enterprise MRG 2.5 that is layered on Red Hat Enterprise Linux 6, and
provides a number of bug fixes and enhancements, including:

• [md] dm: fix AB-BA deadlock in __dm_destroy()
  
• [md] revert "dm-mpath: fix stalls when handling invalid ioctl
  
• [cpufreq] intel_pstate: Fix limits->max_perf and limits->max_policy_pct
  rounding errors
  
• [cpufreq] revert "intel_pstate: fix rounding error in max_freq_pct"
  
• [crypto] nx: 842 - Add CRC and validation support
  
• [of] return NUMA_NO_NODE from fallback of_node_to_nid()
  

(BZ#1277670)

The HP Smart Array (hpsa) SCSI driver has been updated to the latest
version included in a Red Hat release. (BZ#1224096)

This update also fixes the following bugs:

• A heavy load of incoming packets on a fast networking driver (like the
  i40e) will both stress the softirq mechanism on the realtime kernel (as
  described in BZ#1293229) and exercise the possible livelock in the netpoll
  NAPI/busy polling routines (as described in BZ#1293230). The fixes applied
  to both BZ#1293229 and BZ#1293230 will address these issues by hardening
  the locking mechanism for the netpoll NAPI/busy polling and by enhancing
  the way softirqs are serviced. These fixes also create a failsafe to
  avoiding RCU stalls on a heavily loaded system and allows the networking
  driver to work as expected. (BZ#1200766)
  
• The nohz_full code in older versions of the MRG-Realtime kernels was
  incomplete and known to be problematic due to the way the old
  implementation interacted with the real time features in the kernel.
  The nohz_full kernel code has been updated enabling this feature to
  function as expected and allowing this feature to be enabled in the
  realtime kernel. (BZ#1278511)
  
• Because the realtime kernel replaces most of the spinlocks with
  rtmutexes, the locking scheme used in both NAPI polling and busy polling
  could become out of synchronization with the State Machine they protected.
  This could cause system performance degradation or even a livelock
  situation when a machine with faster NICs (10g or 40g) was subject to a
  heavy pressure receiving network packets. The locking schemes on NAPI
  polling and busy polling routines were hardened to enforce the State
  machine sanity to help ensure the system continues to function properly
  under pressure. (BZ#1295884)
  
• A possible livelock in the NAPI polling and busy polling routines could
  lead the system to a livelock on threads running at high, realtime,
  priorities. The threads running at priorities lower than the ones of the
  threads involved in the livelock would be prevented from running on the
  CPUs affected by the livelock. Among those lower priority threads are the
  rcuc/ threads. Right before (4 jiffies) a RCU stall is detected, the rcuc/
  threads on the CPUs facing the livelock have their priorities boosted above
  the priority of the threads involved in the livelock. The softirq code was
  also updated to be more robust. These modifications allowed the rcuc/
  threads to execute even under system pressure, mitigating the RCU stalls.
  (BZ#1295885)
  

All kernel-rt users are advised to upgrade to these updated packages, which
correct these issues and add these enhancements. 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.

For details on how to apply this update, refer to:

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

Affected Products

• MRG Realtime 2 x86_64

Fixes

• BZ - 1259577 - CVE-2015-5157 kernel: x86-64: IRET faults during NMIs processing
• BZ - 1272371 - CVE-2015-7872 kernel: Keyrings crash triggerable by unprivileged user
• BZ - 1277670 - update the MRG 2.5.x 3.10 kernel-rt sources
• BZ - 1278511 - nohz_full still not working even with nohz=on

CVEs

• CVE-2015-7872
• CVE-2015-5157

References

• https://access.redhat.com/security/updates/classification/#important

MRG Realtime 2

SRPM
kernel-rt-3.10.0-327.rt56.171.el6rt.src.rpm	SHA-256: 54b611a8e8279310ef8b21e0302f8e6022e55689966e5f9d45474869eb5ff3b2
x86_64
kernel-rt-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 62b9b9232be88b7135b718d8f1dbc27dc01792e790d5003966e441d49c1dd66b
kernel-rt-debug-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: ebb4bebd54d467c4da0ee535338eefc65cfabc8de0df7d260264a77db317262b
kernel-rt-debug-debuginfo-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 097e823f52a8b4c7d94dab70d80726419272dc21470700167df2680d7d40ca84
kernel-rt-debug-devel-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 417fcf68a8466f0991acfd677507205e0909ef1e09eff8c61d8e2d0533e976b0
kernel-rt-debuginfo-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 708c2c029dc0cfa59e911d0f5245419e940135b31a13e346e11721663e97540c
kernel-rt-debuginfo-common-x86_64-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: e807c6ae597a5b9fa7e7ef36d8cc634750ebe744e1ac2e87a687ce4d60889735
kernel-rt-devel-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 5e6b2b9c26e246baaeeec2794d927247739d1b23cb5266a27ee719c17108dbfb
kernel-rt-doc-3.10.0-327.rt56.171.el6rt.noarch.rpm	SHA-256: c8a799d03ad9e05232719092e72c0dc26f0ec50ea0c96eae19d5e692adffb446
kernel-rt-firmware-3.10.0-327.rt56.171.el6rt.noarch.rpm	SHA-256: 62f280e7b312afcd909ae38b71ed51adf7f245160f77011f7c847c8a6cadf578
kernel-rt-trace-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 48179f05b10e13b72071f5a7f6e69b78a230fdd9fd63abc24d44630ae8d385f1
kernel-rt-trace-debuginfo-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: b1909e652a06560471b419943cb7ec7ca5297ebb5b4457f8c911989b062fd6d3
kernel-rt-trace-devel-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 914e9076587f9d074ce09b132cc272c7761c866257f31be29932d54568f69506
kernel-rt-vanilla-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 3e291b6cfcae5a13a78c296b4fa1cc63a1c05cee2c54c797b50395739a015f0b
kernel-rt-vanilla-debuginfo-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 62b698f7584434f5c336eb5a15d3988f6ac2ee806405f1d97d4e3da7789fba93
kernel-rt-vanilla-devel-3.10.0-327.rt56.171.el6rt.x86_64.rpm	SHA-256: 1d722b62dce78d1954bd3c13bd8ef6c9b399a77606cd8a7755abab48301f86a1