RHEL 6 : kernel (RHSA-2017:1488) (Stack Clash)

This script is Copyright (C) 2017 Tenable Network Security, Inc.


Synopsis :

The remote Red Hat host is missing one or more security updates.

Description :

An update for kernel is now available for Red Hat Enterprise Linux 6.6
Advanced Update Support and Red Hat Enterprise Linux 6.6 Telco
Extended 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.

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)

* A race condition flaw was found in the N_HLDC Linux kernel driver
when accessing n_hdlc.tbuf list that can lead to double free. A local,
unprivileged user able to set the HDLC line discipline on the tty
device could use this flaw to increase their privileges on the system.
(CVE-2017-2636, Important)

Red Hat would like to thank Qualys Research Labs for reporting
CVE-2017-1000364 and Alexander Popov for reporting CVE-2017-2636.

Bug Fix(es) :

* 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#1443497)

* 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#1444349)

* Previously, the vmw_pvscsi driver reported most successful aborts as
FAILED due to a bug in vmw_pvscsi abort handler. This update fixes the
handler, and successful aborts are no longer reported as FAILED.
(BZ#1442966)

See also :

https://www.redhat.com/security/data/cve/CVE-2017-1000364.html
https://www.redhat.com/security/data/cve/CVE-2017-2636.html
https://access.redhat.com/security/vulnerabilities/stackguard
http://rhn.redhat.com/errata/RHSA-2017-1488.html

Solution :

Update the affected packages.

Risk factor :

High / CVSS Base Score : 7.2
(CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C)
CVSS Temporal Score : 6.8
(CVSS2#E:F/RL:U/RC:ND)
Public Exploit Available : true

Family: Red Hat Local Security Checks

Nessus Plugin ID: 100898 ()

Bugtraq ID:

CVE ID: CVE-2017-1000364
CVE-2017-2636

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