[LSN-0022-1] Linux kernel vulnerability

[Benjamin M. Romer]

==========================================================================
Kernel Live Patch Security Notice LSN-0022-1
May 16, 2017

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       |

Summary:

Several security issues were fixed in the kernel.

Software Description:
- linux: Linux kernel

Details:

It was discovered that a use-after-free flaw existed in the filesystem
encryption subsystem in the Linux kernel. A local attacker could use this
to cause a denial of service (system crash). (CVE-2017-7374)

Andreas Gruenbacher and Jan Kara discovered that the filesystem
implementation in the Linux kernel did not clear the setgid bit during a
setxattr call. A local attacker could use this to possibly elevate group
privileges. (CVE-2016-7097)

Update instructions:

The problem can be corrected by updating your livepatches to the following
versions:

| Kernel          | Version  | flavors                  |
|-----------------+----------+--------------------------|
| 4.4.0-21.37     | 22.5     | generic, lowlatency      |
| 4.4.0-22.39     | 22.4     | generic, lowlatency      |
| 4.4.0-22.40     | 22.4     | generic, lowlatency      |
| 4.4.0-24.43     | 22.4     | generic, lowlatency      |
| 4.4.0-28.47     | 22.4     | generic, lowlatency      |
| 4.4.0-31.50     | 22.4     | generic, lowlatency      |
| 4.4.0-34.53     | 22.4     | generic, lowlatency      |
| 4.4.0-36.55     | 22.4     | generic, lowlatency      |
| 4.4.0-38.57     | 22.4     | generic, lowlatency      |
| 4.4.0-42.62     | 22.4     | generic, lowlatency      |
| 4.4.0-43.63     | 22.4     | generic, lowlatency      |
| 4.4.0-45.66     | 22.4     | generic, lowlatency      |
| 4.4.0-47.68     | 22.4     | generic, lowlatency      |
| 4.4.0-51.72     | 22.4     | generic, lowlatency      |
| 4.4.0-53.74     | 22.4     | generic, lowlatency      |
| 4.4.0-57.78     | 22.4     | generic, lowlatency      |
| 4.4.0-59.80     | 22.4     | generic, lowlatency      |
| 4.4.0-62.83     | 22.4     | generic, lowlatency      |
| 4.4.0-63.84     | 22.4     | generic, lowlatency      |
| 4.4.0-64.85     | 22.4     | generic, lowlatency      |
| 4.4.0-66.87     | 22.4     | generic, lowlatency      |
| 4.4.0-67.88     | 22.4     | generic, lowlatency      |
| 4.4.0-70.91     | 22.4     | generic, lowlatency      |
| 4.4.0-71.92     | 22.4     | generic, lowlatency      |
| 4.4.0-71.92     | 22.4     | generic, lowlatency      |
| 4.4.0-72.93     | 22.4     | generic, lowlatency      |

Additionally, you should install an updated kernel with these fixes and
reboot at your convienience.

References:
  CVE-2016-7097, CVE-2017-7374