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 6.6 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.

Description

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

Security Fix(es):

• A stack buffer overflow flaw was found in the way the Bluetooth subsystem of the Linux kernel processed pending L2CAP configuration responses from a client. On systems with the stack protection feature enabled in the kernel (CONFIG_CC_STACKPROTECTOR=y, which is enabled on all architectures other than s390x and ppc64[le]), an unauthenticated attacker able to initiate a connection to a system via Bluetooth could use this flaw to crash the system. Due to the nature of the stack protection feature, code execution cannot be fully ruled out, although we believe it is unlikely. On systems without the stack protection feature (ppc64[le]; the Bluetooth modules are not built on s390x), an unauthenticated attacker able to initiate a connection to a system via Bluetooth could use this flaw to remotely execute arbitrary code on the system with ring 0 (kernel) privileges. (CVE-2017-1000251, Important)

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

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#1474722)

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 - AUS 6.6 x86_64
• Red Hat Enterprise Linux Server - TUS 6.6 x86_64

Fixes

• BZ - 1489716 - CVE-2017-1000251 kernel: stack buffer overflow in the native Bluetooth stack

CVEs

• CVE-2017-1000251

References