==========================================================================
Kernel Live Patch Security Notice 0055-1
September 06, 2019

linux vulnerability
==========================================================================

A security issue affects these releases of Ubuntu:

| Series           | Base kernel  | Arch     | flavors          |
|------------------+--------------+----------+------------------|
| Ubuntu 18.04 LTS | 4.15.0       | amd64    | generic          |
| Ubuntu 18.04 LTS | 4.15.0       | amd64    | lowlatency       |
| Ubuntu 16.04 LTS | 4.4.0        | amd64    | generic          |
| Ubuntu 16.04 LTS | 4.4.0        | amd64    | lowlatency       |
| Ubuntu 16.04 LTS | 4.15.0       | amd64    | generic          |
| Ubuntu 16.04 LTS | 4.15.0       | 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 error existed in the block layer
subsystem of the Linux kernel when certain failure conditions occurred. A
local attacker could possibly use this to cause a denial of service (system
crash) or possibly execute arbitrary code. (CVE-2018-20856)

It was discovered that the Bluetooth UART implementation in the Linux
kernel did not properly check for missing tty operations. A local attacker
could use this to cause a denial of service. (CVE-2019-10207)

Jonathan Looney discovered that the TCP retransmission queue implementation
in the Linux kernel could be fragmented when handling certain TCP Selective
Acknowledgment (SACK) sequences. A remote attacker could use this to cause
a denial of service. (CVE-2019-11478)

Jann Horn discovered a use-after-free vulnerability in the Linux kernel
when accessing LDT entries in some situations. A local attacker could use
this to cause a denial of service (system crash) or possibly execute
arbitrary code. (CVE-2019-13233)

It was discovered that the floppy driver in the Linux kernel did not
properly validate meta data, leading to a buffer overread. A local attacker
could use this to cause a denial of service (system crash). 
(CVE-2019-14283)

It was discovered that the floppy driver in the Linux kernel did not
properly validate ioctl() calls, leading to a division-by-zero. A local
attacker could use this to cause a denial of service (system crash). 
(CVE-2019-14284)

Update instructions:

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

| Kernel                   | Version  | flavors                  |
|--------------------------+----------+--------------------------|
| 4.4.0-148.174            | 55.1     | lowlatency, generic      |
| 4.4.0-150.176            | 55.1     | generic, lowlatency      |
| 4.4.0-151.178            | 55.1     | lowlatency, generic      |
| 4.4.0-154.181            | 55.1     | lowlatency, generic      |
| 4.4.0-157.185            | 55.1     | lowlatency               |
| 4.4.0-159.187            | 55.1     | lowlatency, generic      |
| 4.15.0-50.54             | 55.1     | generic, lowlatency      |
| 4.15.0-50.54~16.04.1     | 55.1     | generic, lowlatency      |
| 4.15.0-51.55             | 55.1     | generic, lowlatency      |
| 4.15.0-51.55~16.04.1     | 55.2     | generic, lowlatency      |
| 4.15.0-52.56             | 55.1     | lowlatency, generic      |
| 4.15.0-52.56~16.04.1     | 55.1     | generic, lowlatency      |
| 4.15.0-54.58             | 55.1     | generic, lowlatency      |
| 4.15.0-54.58~16.04.1     | 55.1     | generic, lowlatency      |
| 4.15.0-55.60             | 55.1     | generic, lowlatency      |
| 4.15.0-58.64             | 55.1     | generic, lowlatency      |
| 4.15.0-58.64~16.04.1     | 55.1     | lowlatency, generic      |

Support Information:

Kernels older than the levels listed below do not receive livepatch
updates. Please upgrade your kernel as soon as possible.

| Series           | Version          | Flavors                  |
|------------------+------------------+--------------------------|
| Ubuntu 18.04 LTS | 4.15.0-50        | generic lowlatency       |
| Ubuntu 16.04 LTS | 4.15.0-50        | generic lowlatency       |
| Ubuntu 16.04 LTS | 4.4.0-148        | generic lowlatency       |
| Ubuntu 14.04 LTS | 4.4.0-148        | generic lowlatency       |

References:
  CVE-2018-20856, CVE-2019-10207, CVE-2019-11478, CVE-2019-13233, 
  CVE-2019-14283, CVE-2019-14284


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