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redhatRedHatRHSA-2016:0185
HistoryFeb 16, 2016 - 10:28 a.m.

(RHSA-2016:0185) Important: kernel security and bug fix update

2016-02-1610:28:15
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78

7.2 High

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:C/I:C/A:C

0.001 Low

EPSS

Percentile

24.5%

The kernel 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 also fixes the following bugs:

  • Previously, processing packets with a lot of different IPv6 source
    addresses caused the kernel to return warnings concerning soft-lockups due
    to high lock contention and latency increase. With this update, lock
    contention is reduced by backing off concurrent waiting threads on the
    lock. As a result, the kernel no longer issues warnings in the described
    scenario. (BZ#1285370)

  • Prior to this update, block device readahead was artificially limited.
    As a consequence, the read performance was poor, especially on RAID
    devices. Now, per-device readahead limits are used for each device instead
    of a global limit. As a result, read performance has improved, especially
    on RAID devices. (BZ#1287550)

  • After injecting an EEH error, the host was previously not recovering and
    observing I/O hangs in HTX tool logs. This update makes sure that when one
    or both of EEH_STATE_MMIO_ACTIVE and EEH_STATE_MMIO_ENABLED flags is marked
    in the PE state, the PE’s IO path is regarded as enabled as well. As a
    result, the host no longer hangs and recovers as expected. (BZ#1289101)

  • The genwqe device driver was previously using the GFP_ATOMIC flag for
    allocating consecutive memory pages from the kernel’s atomic memory pool,
    even in non-atomic situations. This could lead to allocation failures
    during memory pressure. With this update, the genwqe driver’s memory
    allocations use the GFP_KERNEL flag, and the driver can allocate memory
    even during memory pressure situations. (BZ#1289450)

  • The nx842 co-processor for IBM Power Systems could in some circumstances
    provide invalid data due to a data corruption bug during uncompression.
    With this update, all compression and uncompression calls to the nx842
    co-processor contain a cyclic redundancy check (CRC) flag, which forces all
    compression and uncompression operations to check data integrity and
    prevents the co-processor from providing corrupted data. (BZ#1289451)

  • A failed “updatepp” operation on the little-endian variant of IBM Power
    Systems could previously cause a wrong hash value to be used for the next
    hash insert operation in the page table. This could result in a missing
    hash pte update or invalidate operation, potentially causing memory
    corruption. With this update, the hash value is always recalculated after a
    failed “updatepp” operation, avoiding memory corruption. (BZ#1289452)

  • Large Receive Offload (LRO) flag disabling was not being propagated
    downwards from above devices in vlan and bond hierarchy, breaking the flow
    of traffic. This problem has been fixed and LRO flags now propagate
    correctly. (BZ#1292072)

  • Due to rounding errors in the CPU frequency of the intel_pstate driver,
    the CPU frequency never reached the value requested by the user. A kernel
    patch has been applied to fix these rounding errors. (BZ#1296276)

  • When running several containers (up to 100), reports of hung tasks were
    previously reported. This update fixes the AB-BA deadlock in the
    dm_destroy() function, and the hung reports no longer occur. (BZ#1296566)

All kernel users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. The system must be
rebooted for this update to take effect.

7.2 High

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

COMPLETE

Integrity Impact

COMPLETE

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:C/I:C/A:C

0.001 Low

EPSS

Percentile

24.5%