[USN-3718-1] Linux kernel regression

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[USN-3718-1] Linux kernel regression

Steve Beattie
Ubuntu Security Notice USN-3718-1
July 21, 2018

linux, linux-aws, linux-azure, linux-gcp, linux-kvm, linux-oem regression

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS


A regression that caused boot failures was fixed in the Linux kernel.

Software Description:
- linux: Linux kernel
- linux-aws: Linux kernel for Amazon Web Services (AWS) systems
- linux-azure: Linux kernel for Microsoft Azure Cloud systems
- linux-gcp: Linux kernel for Google Cloud Platform (GCP) systems
- linux-kvm: Linux kernel for cloud environments
- linux-oem: Linux kernel for OEM processors


USN-3695-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04
LTS. Unfortunately, the fix for CVE-2018-1108 introduced a regression
where insufficient early entropy prevented services from starting,
leading in some situations to a failure to boot, This update addresses
the issue.

We apologize for the inconvenience.

Original advisory details:

 Jann Horn discovered that the Linux kernel's implementation of random
 seed data reported that it was in a ready state before it had gathered
 sufficient entropy. An attacker could use this to expose sensitive
 information. (CVE-2018-1108)

 Wen Xu discovered that the ext4 file system implementation in the Linux
 kernel did not properly initialize the crc32c checksum driver. A local
 attacker could use this to cause a denial of service (system crash).

 It was discovered that the cdrom driver in the Linux kernel contained an
 incorrect bounds check. A local attacker could use this to expose sensitive
 information (kernel memory). (CVE-2018-10940)

 Wen Xu discovered that the ext4 file system implementation in the Linux
 kernel did not properly validate xattr sizes. A local attacker could use
 this to cause a denial of service (system crash). (CVE-2018-1095)

 Jann Horn discovered that the 32 bit adjtimex() syscall implementation for
 64 bit Linux kernels did not properly initialize memory returned to user
 space in some situations. A local attacker could use this to expose
 sensitive information (kernel memory). (CVE-2018-11508)

 It was discovered that an information leak vulnerability existed in the
 floppy driver in the Linux kernel. A local attacker could use this to
 expose sensitive information (kernel memory). (CVE-2018-7755)

Update instructions:

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

Ubuntu 18.04 LTS:
  linux-image-4.15.0-1014-gcp     4.15.0-1014.14
  linux-image-4.15.0-1016-aws     4.15.0-1016.16
  linux-image-4.15.0-1016-kvm     4.15.0-1016.16
  linux-image-4.15.0-1018-azure   4.15.0-1018.18
  linux-image-4.15.0-29-generic   4.15.0-29.31
  linux-image-4.15.0-29-generic-lpae  4.15.0-29.31
  linux-image-4.15.0-29-lowlatency  4.15.0-29.31
  linux-image-4.15.0-29-snapdragon  4.15.0-29.31

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

  https://launchpad.net/bugs/1779827, https://usn.ubuntu.com/usn/usn-3695-1

Package Information:

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