[RHSA-2017:1491-01] Important: kernel security and bug fix update

Mon Jun 19 20:27:59 UTC 2017

An update for kernel is now available for Red Hat Enterprise Linux 6.2
Advanced Update Support.

Red Hat Product Security has rated this update as having a security impact
of Important. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available for each vulnerability
from the CVE link(s) in the References section.

2. Relevant releases/architectures:

Red Hat Enterprise Linux Server AUS (v. 6.2) - noarch, x86_64
Red Hat Enterprise Linux Server Optional AUS (v. 6.2) - x86_64

3. Description:

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

Security Fix(es):

* A flaw was found in the way memory was being allocated on the stack for
user space binaries. If heap (or different memory region) and stack memory
regions were adjacent to each other, an attacker could use this flaw to
jump over the stack guard gap, cause controlled memory corruption on
process stack or the adjacent memory region, and thus increase their
privileges on the system. This is a kernel-side mitigation which increases
the stack guard gap size from one page to 1 MiB to make successful
exploitation of this issue more difficult. (CVE-2017-1000364, Important)

Red Hat would like to thank Qualys Research Labs for reporting this issue.

Bug Fix(es):

* Previously, a kernel panic occurred when the mcelog daemon executed a
huge page memory offline. This update fixes the HugeTLB feature of the
Linux kernel to check for the Page Table Entry (PTE) NULL pointer in the
page_check_address() function. As a result, the kernel panic no longer
occurs under the described circumstances. (BZ#1444342)

* Previously, the kdump mechanism was trying to get the lock by the
vmalloc_sync_all() function during a kernel panic. Consequently, a deadlock
occurred, and the crashkernel did not boot. This update fixes the
vmalloc_sync_all() function to avoid synchronizing the vmalloc area on the
crashing CPU. As a result, the crashkernel parameter now boots as expected,
and the kernel dump is collected successfully under the described
circumstances. (BZ#1443494)

4. Solution:

For details on how to apply this update, which includes the changes
described in this advisory, refer to:

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

The system must be rebooted for this update to take effect.

5. Bugs fixed (https://bugzilla.redhat.com/):

1461333 - CVE-2017-1000364 kernel: heap/stack gap jumping via unbounded stack allocations

6. Package List:

Red Hat Enterprise Linux Server AUS (v. 6.2):

Source:
kernel-2.6.32-220.72.2.el6.src.rpm

noarch:
kernel-doc-2.6.32-220.72.2.el6.noarch.rpm
kernel-firmware-2.6.32-220.72.2.el6.noarch.rpm

x86_64:
kernel-2.6.32-220.72.2.el6.x86_64.rpm
kernel-debug-2.6.32-220.72.2.el6.x86_64.rpm
kernel-debug-debuginfo-2.6.32-220.72.2.el6.x86_64.rpm
kernel-debug-devel-2.6.32-220.72.2.el6.x86_64.rpm
kernel-debuginfo-2.6.32-220.72.2.el6.x86_64.rpm
kernel-debuginfo-common-x86_64-2.6.32-220.72.2.el6.x86_64.rpm
kernel-devel-2.6.32-220.72.2.el6.x86_64.rpm
kernel-headers-2.6.32-220.72.2.el6.x86_64.rpm
perf-2.6.32-220.72.2.el6.x86_64.rpm
perf-debuginfo-2.6.32-220.72.2.el6.x86_64.rpm
python-perf-debuginfo-2.6.32-220.72.2.el6.x86_64.rpm

Red Hat Enterprise Linux Server Optional AUS (v. 6.2):

Source:
kernel-2.6.32-220.72.2.el6.src.rpm

x86_64:
kernel-debug-debuginfo-2.6.32-220.72.2.el6.x86_64.rpm
kernel-debuginfo-2.6.32-220.72.2.el6.x86_64.rpm
kernel-debuginfo-common-x86_64-2.6.32-220.72.2.el6.x86_64.rpm
perf-debuginfo-2.6.32-220.72.2.el6.x86_64.rpm
python-perf-2.6.32-220.72.2.el6.x86_64.rpm
python-perf-debuginfo-2.6.32-220.72.2.el6.x86_64.rpm

These packages are GPG signed by Red Hat for security.  Our key and
details on how to verify the signature are available from
https://access.redhat.com/security/team/key/

7. References:

https://access.redhat.com/security/cve/CVE-2017-1000364
https://access.redhat.com/security/updates/classification/#important
https://access.redhat.com/security/vulnerabilities/stackguard

8. Contact:

The Red Hat security contact is <secalert at redhat.com>. More contact
details at https://access.redhat.com/security/team/contact/

Copyright 2017 Red Hat, Inc.
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