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CVE-2019-15794

Publication date 8 November 2019

Last updated 24 July 2024

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

6.7 · Medium

Score breakdown

Overlayfs in the Linux kernel and shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, both replace vma->vm_file in their mmap handlers. On error the original value is not restored, and the reference is put for the file to which vm_file points. On upstream kernels this is not an issue, as no callers dereference vm_file following after call_mmap() returns an error. However, the aufs patchs change mmap_region() to replace the fput() using a local variable with vma_fput(), which will fput() vm_file, leading to a refcount underflow.

From the Ubuntu Security Team

Jann Horn discovered that the OverlayFS and ShiftFS Drivers in the Linux kernel did not properly handle reference counting during memory mapping operations when used in conjunction with AUFS. A local attacker could use this to cause a denial of service (system crash) or possibly execute arbitrary code.

Status

Package Ubuntu Release Status
linux 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-24.26
19.04 disco
Fixed 5.0.0-37.40
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Ignored
linux-aws 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1008.9
19.04 disco
Fixed 5.0.0-1022.25
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Ignored
linux-aws-5.0 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Fixed 5.0.0-1022.25~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-hwe 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-azure 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1008.9
19.04 disco
Fixed 5.0.0-1027.29
18.04 LTS bionic
Fixed 5.0.0-1027.29~18.04.1
16.04 LTS xenial
Not affected
14.04 LTS trusty Ignored
linux-azure-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Fixed 5.3.0-1008.9~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-edge 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-gcp 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1009.10
19.04 disco
Fixed 5.0.0-1026.27
18.04 LTS bionic
Fixed 5.0.0-1026.27~18.04.1
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-gcp-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Fixed 5.3.0-1009.10~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-edge 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-4.15 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-5.0 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Fixed 5.0.0-1026.27~18.04.2
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gke-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Fixed 5.0.0-37.40~18.04.1
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-hwe-edge 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Ignored
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-kvm 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1008.9
19.04 disco
Fixed 5.0.0-1023.25
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-lts-trusty 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-lts-xenial 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Ignored
linux-oem 20.04 LTS focal Not in release
19.10 eoan
Not affected
19.04 disco
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial Ignored
14.04 LTS trusty Not in release
linux-oem-5.6 20.04 LTS focal
Not affected
19.10 eoan Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem-osp1 20.04 LTS focal Not in release
19.10 eoan
Fixed 5.0.0-1030.34
19.04 disco Ignored
18.04 LTS bionic
Fixed 5.0.0-1030.34
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle 20.04 LTS focal
Not affected
19.10 eoan
Fixed 5.3.0-1007.8
19.04 disco
Fixed 5.0.0-1008.13
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-oracle-5.0 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Not in release
18.04 LTS bionic
Fixed 5.0.0-1008.13~18.04.1
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-raspi2 20.04 LTS focal Ignored
19.10 eoan
Fixed 5.3.0-1014.16
19.04 disco
Fixed 5.0.0-1023.24
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release
linux-raspi2-5.3 20.04 LTS focal Not in release
19.10 eoan Not in release
18.04 LTS bionic
Not affected
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-snapdragon 20.04 LTS focal Not in release
19.10 eoan Not in release
19.04 disco Ignored
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty Not in release

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
linux

Severity score breakdown

Parameter Value
Base score 6.7 · Medium
Attack vector Local
Attack complexity Low
Privileges required High
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

    • USN-4209-1
    • Linux kernel vulnerabilities
    • 2 December 2019
    • USN-4208-1
    • Linux kernel vulnerabilities
    • 2 December 2019

Other references