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Ubuntu: (Multiple Advisories) (CVE-2020-16120): Linux kernel vulnerabilities

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Ubuntu: (Multiple Advisories) (CVE-2020-16120): Linux kernel vulnerabilities

Severity
2
CVSS
(AV:L/AC:L/Au:N/C:P/I:N/A:N)
Published
10/14/2020
Created
10/16/2020
Added
10/14/2020
Modified
07/06/2021

Description

Overlayfs did not properly perform permission checking when copying up files in an overlayfs and could be exploited from within a user namespace, if, for example, unprivileged user namespaces were allowed. It was possible to have a file not readable by an unprivileged user to be copied to a mountpoint controlled by the user, like a removable device. This was introduced in kernel version 4.19 by commit d1d04ef ("ovl: stack file ops"). This was fixed in kernel version 5.8 by commits 56230d9 ("ovl: verify permissions in ovl_path_open()"), 48bd024 ("ovl: switch to mounter creds in readdir") and 05acefb ("ovl: check permission to open real file"). Additionally, commits 130fdbc ("ovl: pass correct flags for opening real directory") and 292f902 ("ovl: call secutiry hook in ovl_real_ioctl()") in kernel 5.8 might also be desired or necessary. These additional commits introduced a regression in overlay mounts within user namespaces which prevented access to files with ownership outside of the user namespace. This regression was mitigated by subsequent commit b6650da ("ovl: do not fail because of O_NOATIMEi") in kernel 5.11.

Solution(s)

  • ubuntu-upgrade-linux-image-4-15-0-1056-oracle
  • ubuntu-upgrade-linux-image-4-15-0-1057-oracle
  • ubuntu-upgrade-linux-image-4-15-0-1072-gke
  • ubuntu-upgrade-linux-image-4-15-0-1073-raspi2
  • ubuntu-upgrade-linux-image-4-15-0-1077-kvm
  • ubuntu-upgrade-linux-image-4-15-0-1085-aws
  • ubuntu-upgrade-linux-image-4-15-0-1086-aws
  • ubuntu-upgrade-linux-image-4-15-0-1086-gcp
  • ubuntu-upgrade-linux-image-4-15-0-1089-snapdragon
  • ubuntu-upgrade-linux-image-4-15-0-1098-azure
  • ubuntu-upgrade-linux-image-4-15-0-1099-azure
  • ubuntu-upgrade-linux-image-4-15-0-1099-oem
  • ubuntu-upgrade-linux-image-4-15-0-120-generic
  • ubuntu-upgrade-linux-image-4-15-0-120-generic-lpae
  • ubuntu-upgrade-linux-image-4-15-0-120-lowlatency
  • ubuntu-upgrade-linux-image-4-15-0-121-generic
  • ubuntu-upgrade-linux-image-4-15-0-121-generic-lpae
  • ubuntu-upgrade-linux-image-4-15-0-121-lowlatency
  • ubuntu-upgrade-linux-image-5-0-0-1049-gke
  • ubuntu-upgrade-linux-image-5-0-0-1069-oem-osp1
  • ubuntu-upgrade-linux-image-5-3-0-1035-raspi2
  • ubuntu-upgrade-linux-image-5-3-0-1038-gke
  • ubuntu-upgrade-linux-image-5-3-0-68-generic
  • ubuntu-upgrade-linux-image-5-3-0-68-lowlatency
  • ubuntu-upgrade-linux-image-5-4-0-1021-raspi
  • ubuntu-upgrade-linux-image-5-4-0-1026-kvm
  • ubuntu-upgrade-linux-image-5-4-0-1028-aws
  • ubuntu-upgrade-linux-image-5-4-0-1028-gcp
  • ubuntu-upgrade-linux-image-5-4-0-1028-oracle
  • ubuntu-upgrade-linux-image-5-4-0-1031-azure
  • ubuntu-upgrade-linux-image-5-4-0-51-generic
  • ubuntu-upgrade-linux-image-5-4-0-51-generic-lpae
  • ubuntu-upgrade-linux-image-5-4-0-51-lowlatency
  • ubuntu-upgrade-linux-image-aws
  • ubuntu-upgrade-linux-image-aws-hwe
  • ubuntu-upgrade-linux-image-aws-lts-18-04
  • ubuntu-upgrade-linux-image-azure
  • ubuntu-upgrade-linux-image-azure-lts-18-04
  • ubuntu-upgrade-linux-image-gcp
  • ubuntu-upgrade-linux-image-gcp-lts-18-04
  • ubuntu-upgrade-linux-image-generic
  • ubuntu-upgrade-linux-image-generic-hwe-16-04
  • ubuntu-upgrade-linux-image-generic-hwe-18-04
  • ubuntu-upgrade-linux-image-generic-hwe-20-04
  • ubuntu-upgrade-linux-image-generic-lpae
  • ubuntu-upgrade-linux-image-generic-lpae-hwe-16-04
  • ubuntu-upgrade-linux-image-generic-lpae-hwe-18-04
  • ubuntu-upgrade-linux-image-generic-lpae-hwe-20-04
  • ubuntu-upgrade-linux-image-gke
  • ubuntu-upgrade-linux-image-gke-4-15
  • ubuntu-upgrade-linux-image-gke-5-0
  • ubuntu-upgrade-linux-image-gke-5-3
  • ubuntu-upgrade-linux-image-gkeop-5-3
  • ubuntu-upgrade-linux-image-kvm
  • ubuntu-upgrade-linux-image-lowlatency
  • ubuntu-upgrade-linux-image-lowlatency-hwe-16-04
  • ubuntu-upgrade-linux-image-lowlatency-hwe-18-04
  • ubuntu-upgrade-linux-image-lowlatency-hwe-20-04
  • ubuntu-upgrade-linux-image-oem
  • ubuntu-upgrade-linux-image-oem-osp1
  • ubuntu-upgrade-linux-image-oracle
  • ubuntu-upgrade-linux-image-oracle-lts-18-04
  • ubuntu-upgrade-linux-image-raspi
  • ubuntu-upgrade-linux-image-raspi-hwe-18-04
  • ubuntu-upgrade-linux-image-raspi2
  • ubuntu-upgrade-linux-image-raspi2-hwe-18-04
  • ubuntu-upgrade-linux-image-snapdragon
  • ubuntu-upgrade-linux-image-snapdragon-hwe-18-04
  • ubuntu-upgrade-linux-image-virtual
  • ubuntu-upgrade-linux-image-virtual-hwe-16-04
  • ubuntu-upgrade-linux-image-virtual-hwe-18-04
  • ubuntu-upgrade-linux-image-virtual-hwe-20-04

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