Synopsis
Important: kernel security and bug fix update
Type/Severity
Security Advisory: Important
Topic
An update for kernel is now available for Red Hat Enterprise Linux 6.7 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.
Description
The kernel packages contain the Linux kernel, the core of any Linux operating system.
Security Fix(es):
- It was found that stacking a file system over procfs in the Linux kernel could lead to a kernel stack overflow due to deep nesting, as demonstrated by mounting ecryptfs over procfs and creating a recursion by mapping /proc/environ. An unprivileged, local user could potentially use this flaw to escalate their privileges on the system. (CVE-2016-1583, Important)
Bug Fix(es):
- Previously, while the MAP_GROWSDOWN flag was set, writing to the memory which was mapped with the mmap system call failed with the SIGBUS signal. This update fixes memory management in the Linux kernel by backporting an upstream patch that enlarges the stack guard page gap. As a result, mmap now works as expected under the described circumstances. (BZ#1474721)
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.
Affected Products
-
Red Hat Enterprise Linux Server - Extended Update Support 6.7 x86_64
-
Red Hat Enterprise Linux Server - Extended Update Support 6.7 i386
-
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support 6.7 s390x
-
Red Hat Enterprise Linux for Power, big endian - Extended Update Support 6.7 ppc64
-
Red Hat Enterprise Linux EUS Compute Node 6.7 x86_64
-
RHEL for SAP HANA - Extended Update Support 6.7 x86_64
Fixes
- BZ - 1344721 - CVE-2016-1583 kernel: Stack overflow via ecryptfs and /proc/$pid/environ
CVEs
References
Vulmon