USN-3835-1: Linux kernel vulnerabilities

Published Dec 3, 2018
·
Updated

Jann Horn discovered that the procfs file system implementation in the Linux kernel did not properly restrict the ability to inspect the kernel stack of an arbitrary task. A local attacker could use this to expose sensitive information. (CVE-2018-17972) Jann Horn discovered that the mremap() system call in the Linux kernel did not properly flush the TLB when completing, potentially leaving access to a physical page after it has been released to the page allocator. A local attacker could use this to cause a denial of service (system crash), expose sensitive information, or possibly execute arbitrary code. (CVE-2018-18281) It was discovered that the BPF verifier in the Linux kernel did not correctly compute numeric bounds in some situations. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code. (CVE-2018-18445) Daniel Dadap discovered that the module loading implementation in the Linux kernel did not properly enforce signed module loading when booted with UEFI Secure Boot in some situations. A local privileged attacker could use this to execute untrusted code in the kernel. (CVE-2018-18653) Jann Horn discovered that the Linux kernel mishandles mapping UID or GID ranges inside nested user namespaces in some situations. A local attacker could use this to bypass access controls on resources outside the namespace. (CVE-2018-18955) Philipp Wendler discovered that the overlayfs implementation in the Linux kernel did not properly verify the directory contents permissions from within a unprivileged user namespace. A local attacker could use this to expose sensitive information (protected file names). (CVE-2018-6559)

Affected Software

31 affected componentsFixes available
Canonical Linux kernel
All of the following
ubuntu/linux-image-gke<4.18.0.1004.4
4.18.0.1004.4
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-generic<4.18.0.12.13
4.18.0.12.13
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-4.18.0-12-generic<4.18.0-12.13
4.18.0-12.13
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-4.18.0-12-snapdragon<4.18.0-12.13
4.18.0-12.13
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-4.18.0-1007-raspi2<4.18.0-1007.9
4.18.0-1007.9
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-gcp<4.18.0.1004.4
4.18.0.1004.4
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-4.18.0-12-generic-lpae<4.18.0-12.13
4.18.0-12.13
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-4.18.0-1004-gcp<4.18.0-1004.5
4.18.0-1004.5
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-4.18.0-12-lowlatency<4.18.0-12.13
4.18.0-12.13
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-generic-lpae<4.18.0.12.13
4.18.0.12.13
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-4.18.0-1005-kvm<4.18.0-1005.5
4.18.0-1005.5
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-snapdragon<4.18.0.12.13
4.18.0.12.13
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-kvm<4.18.0.1005.5
4.18.0.1005.5
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-lowlatency<4.18.0.12.13
4.18.0.12.13
Ubuntu Ubuntu=18.10
All of the following
ubuntu/linux-image-raspi2<4.18.0.1007.4
4.18.0.1007.4
Ubuntu Ubuntu=18.10

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade ubuntu/linux-image-gke to a version that resolves this vulnerability.

    Fixed in 4.18.0.1004.4
  2. Upgrade

    Upgrade ubuntu/linux-image-generic to a version that resolves this vulnerability.

    Fixed in 4.18.0.12.13
  3. Upgrade

    Upgrade ubuntu/linux-image-4.18.0-12-generic to a version that resolves this vulnerability.

    Fixed in 4.18.0-12.13
  4. Upgrade

    Upgrade ubuntu/linux-image-4.18.0-12-snapdragon to a version that resolves this vulnerability.

    Fixed in 4.18.0-12.13
  5. Upgrade

    Upgrade ubuntu/linux-image-4.18.0-1007-raspi2 to a version that resolves this vulnerability.

    Fixed in 4.18.0-1007.9
  6. Upgrade

    Upgrade ubuntu/linux-image-gcp to a version that resolves this vulnerability.

    Fixed in 4.18.0.1004.4
  7. Upgrade

    Upgrade ubuntu/linux-image-4.18.0-12-generic-lpae to a version that resolves this vulnerability.

    Fixed in 4.18.0-12.13
  8. Upgrade

    Upgrade ubuntu/linux-image-4.18.0-1004-gcp to a version that resolves this vulnerability.

    Fixed in 4.18.0-1004.5
  9. Upgrade

    Upgrade ubuntu/linux-image-4.18.0-12-lowlatency to a version that resolves this vulnerability.

    Fixed in 4.18.0-12.13
  10. Upgrade

    Upgrade ubuntu/linux-image-generic-lpae to a version that resolves this vulnerability.

    Fixed in 4.18.0.12.13
  11. Upgrade

    Upgrade ubuntu/linux-image-4.18.0-1005-kvm to a version that resolves this vulnerability.

    Fixed in 4.18.0-1005.5
  12. Upgrade

    Upgrade ubuntu/linux-image-snapdragon to a version that resolves this vulnerability.

    Fixed in 4.18.0.12.13
  13. Upgrade

    Upgrade ubuntu/linux-image-kvm to a version that resolves this vulnerability.

    Fixed in 4.18.0.1005.5
  14. Upgrade

    Upgrade ubuntu/linux-image-lowlatency to a version that resolves this vulnerability.

    Fixed in 4.18.0.12.13
  15. Upgrade

    Upgrade ubuntu/linux-image-raspi2 to a version that resolves this vulnerability.

    Fixed in 4.18.0.1007.4
  16. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Patch USN-3835-1

Event History

Dec 3, 2018
Advisory Published
via Ubuntu·12:00 AM
Data Sourced
via Ubuntu·12:00 AM
DescriptionAffected Software

Child vulnerabilities

Contains the following vulnerabilities.

Frequently Asked Questions

1

What is the vulnerability ID for this advisory?

The vulnerability ID for this advisory is CVE-2018-17972.

2

What is the impact of CVE-2018-17972?

CVE-2018-17972 allows a local attacker to expose sensitive information by inspecting the kernel stack of an arbitrary task.

3

Which versions of Ubuntu are affected by CVE-2018-17972?

Ubuntu version 18.10 is affected by CVE-2018-17972.

4

How can I fix CVE-2018-17972?

To fix CVE-2018-17972, update to Linux kernel version 4.18.0.1004.4 or later.

5

Where can I find more information about CVE-2018-17972?

You can find more information about CVE-2018-17972 on the Ubuntu Security Advisory page: [link](https://ubuntu.com/security/CVE-2018-17972).

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