ESB-2018.0562 - [Ubuntu] Linux kernel: Access privileged data - Existing account 2018-02-26

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             AUSCERT External Security Bulletin Redistribution

               Kernel Live Patch Security Notice LSN-0035-1
                             26 February 2018


        AusCERT Security Bulletin Summary

Product:           Linux kernel
Publisher:         Ubuntu
Operating System:  Ubuntu
Impact/Access:     Access Privileged Data -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2017-5715  

Reference:         ASB-2018.0009

Original Bulletin:

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Kernel Live Patch Security Notice LSN-0035-1
February 22, 2018

linux vulnerability

A security issue affects these releases of Ubuntu:

| Series           | Base kernel  | Arch     | flavors          |
| Ubuntu 16.04 LTS | 4.4.0        | amd64    | generic          |
| Ubuntu 16.04 LTS | 4.4.0        | amd64    | lowlatency       |
| Ubuntu 14.04 LTS | 4.4.0        | amd64    | generic          |
| Ubuntu 14.04 LTS | 4.4.0        | amd64    | lowlatency       |


On February 22, fixes for CVE-2017-5715 were released into the Ubuntu Xenial
kernel version 4.4.0-116.140. This CVE, also known as "Spectre," is caused 
by flaws in the design of speculative execution hardware in the computer's
CPU, and could be used to access sensitive information in kernel memory.

The mitigation for "Spectre" is accomplished using retpoline, a new compiler
feature that prevents speculation when an indirect call is made. Unfortunately,
it is not possible to generate a livepatch when a compiler change is required
by a fix, as livepatches must be generated with the same compiler as the
target kernel. Please plan to reboot into kernel version 4.4.0-116.140 or 
newer as soon as possible.

Additional details on the vulnerability and our response can be found here:

Software Description:
- - linux: Linux kernel

Update instructions:

The problem can be corrected by installing an updated kernel with these
fixes and rebooting.


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