Vulnerability of Linux kernel: use after free via vt_do_kdgkb_ioctl

Synthesis of the vulnerability

An attacker can force the usage of a freed memory area via vt_do_kdgkb_ioctl() of the Linux kernel, in order to trigger a denial of service, and possibly to run code.

Impacted systems: Debian, Fedora, Linux, openSUSE Leap, RHEL, SUSE Linux Enterprise Desktop, SLES, Ubuntu.

Severity of this alert: 2/4.

Creation date: 16/10/2020.

Références of this alert: 1177766, CERTFR-2020-AVI-741, CERTFR-2020-AVI-750, CERTFR-2020-AVI-764, CERTFR-2020-AVI-769, CERTFR-2020-AVI-776, CERTFR-2020-AVI-784, CERTFR-2020-AVI-834, CERTFR-2021-AVI-006, CERTFR-2021-AVI-125, CERTFR-2021-AVI-149, CERTFR-2021-AVI-201, CVE-2020-25656, DLA-2483-1, DLA-2494-1, FEDORA-2020-98ccae320c, FEDORA-2020-e211716d08, openSUSE-SU-2020:1906-1, openSUSE-SU-2020:2112-1, openSUSE-SU-2021:0242-1, RHSA-2021:0856-01, RHSA-2021:0857-01, SUSE-SU-2020:3272-1, SUSE-SU-2020:3273-1, SUSE-SU-2020:3281-1, SUSE-SU-2020:3326-1, SUSE-SU-2020:3484-1, SUSE-SU-2020:3491-1, SUSE-SU-2020:3501-1, SUSE-SU-2020:3503-1, SUSE-SU-2020:3512-1, SUSE-SU-2020:3513-1, SUSE-SU-2020:3522-1, SUSE-SU-2020:3532-1, SUSE-SU-2020:3544-1, SUSE-SU-2021:14630-1, USN-4679-1, USN-4680-1, USN-4681-1, USN-4751-1, VIGILANCE-VUL-33611.

Description of the vulnerability

An attacker can force the usage of a freed memory area via vt_do_kdgkb_ioctl() of the Linux kernel, in order to trigger a denial of service, and possibly to run code.
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This cybersecurity announce impacts software or systems such as Debian, Fedora, Linux, openSUSE Leap, RHEL, SUSE Linux Enterprise Desktop, SLES, Ubuntu.

Our Vigil@nce team determined that the severity of this threat alert is medium.

The trust level is of type confirmed by the editor, with an origin of document.

An attacker with a expert ability can exploit this computer weakness alert.

Solutions for this threat

Linux kernel: patch for vt_do_kdgkb_ioctl.
A patch is indicated in information sources.

Debian 9: new linux-4.19 packages (10/12/2020).
New packages are available:
Debian 9: linux-4.19 4.19.160-2~deb9u1

Debian 9: new linux packages.
New packages are available:
Debian 9: linux 4.9.246-2

Fedora 32-33: new kernel-headers packages.
New packages are available:
Fedora 32: kernel-headers 5.9.7-100.fc32
Fedora 33: kernel-headers 5.9.7-200.fc33

Fedora 32-33: new kernel packages.
New packages are available:
Fedora 32: kernel 5.9.8-100.fc32
Fedora 33: kernel 5.9.8-200.fc33

Fedora 32-33: new kernel-tools packages.
New packages are available:
Fedora 32: kernel-tools 5.9.7-100.fc32
Fedora 33: kernel-tools 5.9.7-200.fc33

openSUSE Leap 15.2: new kernel packages (13/11/2020).
New packages are available:
openSUSE Leap 15.2: kernel 5.3.18-lp152.50.1

openSUSE Leap 15.2: new kernel packages (30/11/2020).
New packages are available:
openSUSE Leap 15.2: kernel 5.3.18-lp152.50.1.lp152.8.10.1

openSUSE Leap 15.2: new kernel-rt packages.
New packages are available:
openSUSE Leap 15.2: kernel-rt 5.3.18-lp152.3.5.1

RHEL 7.9: new kernel packages.
New packages are available:
RHEL 7.9: kernel 3.10.0-1160.21.1.el7

RHEL 7.9: new kernel-rt packages.
New packages are available:
RHEL 7.9: kernel-rt 3.10.0-1160.21.1.rt56.1158.el7

SUSE LE 11 SP4: new kernel packages.
New packages are available:
SUSE LE 11 SP4: kernel 3.0.101-108.120.1

SUSE LE 12 SP2: new kernel-default packages.
New packages are available:
SUSE LE 12 SP2: kernel-default 4.4.121-92.146.1
SUSE LE 12 SP2: kernel-default 4.4.121-92.146.1

SUSE LE 12 SP3: new kernel-default packages.
New packages are available:
SUSE LE 12 SP3: kernel-default 4.4.180-94.135.1

SUSE LE 12 SP4: new kernel-default packages.
New packages are available:
SUSE LE 12 SP4: kernel-default 4.12.14-95.65.1

SUSE LE 12 SP5: new kernel-azure packages.
New packages are available:
SUSE LE 12 SP5: kernel-azure 4.12.14-16.34.1

SUSE LE 12 SP5: new kernel packages (16/11/2020).
New packages are available:
SUSE LE 12 SP5: kernel 4.12.14-122.51.2

SUSE LE 12 SP5: new kernel-rt packages.
New packages are available:
SUSE LE 12 SP5: kernel-rt 4.12.14-10.22.1

SUSE LE 15: new kernel packages.
New packages are available:
SUSE LE 15 RTM: kernel-default-livepatch 4.12.14-150.63.1, kernel-livepatch 4_12_14-150_63-default-1-1.5.1

SUSE LE 15 SP1: new kernel-azure packages (24/11/2020).
New packages are available:
SUSE LE 15 SP1: kernel-azure 4.12.14-8.52.1

SUSE LE 15 SP1: new kernel packages.
New packages are available:
SUSE LE 15 SP1: kernel 4.12.14-197.67.1

SUSE LE 15 SP1: new kernel-rt packages.
New packages are available:
SUSE LE 15 SP1: kernel-rt 4.12.14-14.41.2

SUSE LE 15 SP2: new kernel-azure packages (24/11/2020).
New packages are available:
SUSE LE 15 SP2: kernel-azure 5.3.18-18.24.1

SUSE LE 15 SP2: new kernel packages.
New packages are available:
SUSE LE 15 SP2: kernel 5.3.18-24.37.1

SUSE LE 15 SP2: new kernel-rt packages (26/11/2020).
New packages are available:
SUSE LE 15 SP2: kernel-rt 5.3.18-16.1

Ubuntu 20: new linux-image-5.8.0 packages.
New packages are available:
Ubuntu 20.04 LTS: linux-image-generic-hwe-20.04 5.8.0.44.50~20.04.30
Ubuntu 20.10: linux-image-generic 5.8.0.44.49

Ubuntu: new linux-image-4.15.0 packages.
New packages are available:
  Ubuntu 14.04 ESM: linux-image-azure 4.15.0.1103.78
  Ubuntu 16.04 LTS: linux-image-generic-hwe-16.04 4.15.0.129.128
  Ubuntu 18.04 LTS: linux-image-generic 4.15.0.129.116

Ubuntu: new linux-image-4.4.0 packages (06/01/2021).
New packages are available:
Ubuntu 14.04 ESM: linux-image-generic-lts-xenial 4.4.0.198.173
Ubuntu 16.04 LTS: linux-image-generic 4.4.0.198.204

Ubuntu: new linux-image-5.4.0 packages.
New packages are available:
Ubuntu 18.04 LTS: linux-image-generic-hwe-18.04 5.4.0.59.65~18.04.54
Ubuntu 20.04 LTS: linux-image-generic 5.4.0.59.62
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