[LSN-0038-1] Linux kernel vulnerability

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[LSN-0038-1] Linux kernel vulnerability

benjamin.romer
==========================================================================
Kernel Live Patch Security Notice LSN-0038-1
May 8, 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       |

Summary:

On May 8, fixes for CVE-2018-1087 and CVE-2018-8897 were released in linux
kernel version 4.4.0-124.148. These CVEs are both related to the way that
the linux kernel handles certain interrupt and exception instructions. If
an interrupt or exception instruction (INT3, SYSCALL, etc.) is immediately
preceded by a MOV SS or POP SS instruction, the resulting interrupt will
be incorrectly handled, possibly crashing the operating system. The issue
can be triggered by an unprivileged user.

The fix for this problem requires modification of the interrupt descriptor
tables (IDT), and modification of the interrupt handlers. Livepatch is
unable to safely modify these areas, so upgrading to a corrected kernel
and rebooting is required to fix the problem.

Additional information about this problem can be found here:
- https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/Pop_SS

Software Description:
- linux: Linux kernel

Update instructions:

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

References:
CVE-2018-1087, CVE-2018-8897

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