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Vulnerability of Linux kernel: buffer overflow via fbcon_redraw_softback

Synthesis of the vulnerability 

An attacker can trigger a buffer overflow via fbcon_redraw_softback() of the Linux kernel, in order to trigger a denial of service, and possibly to run code.
Impacted products: Debian, Linux, openSUSE Leap, Slackware, SUSE Linux Enterprise Desktop, SLES, Ubuntu.
Severity of this bulletin: 2/4.
Creation date: 15/09/2020.
Références of this threat: CERTFR-2020-AVI-614, CERTFR-2020-AVI-625, CERTFR-2020-AVI-642, CERTFR-2020-AVI-672, CERTFR-2020-AVI-678, CERTFR-2020-AVI-699, CERTFR-2020-AVI-764, CERTFR-2020-AVI-776, CERTFR-2020-AVI-784, CERTFR-2020-AVI-786, CERTFR-2021-AVI-125, CVE-2020-14390, DLA-2385-1, DLA-2420-1, DLA-2420-2, openSUSE-SU-2020:1586-1, openSUSE-SU-2020:1655-1, openSUSE-SU-2021:0242-1, SSA:2020-295-01, SUSE-SU-2020:2879-1, SUSE-SU-2020:2904-1, SUSE-SU-2020:2905-1, SUSE-SU-2020:2906-1, SUSE-SU-2020:2907-1, SUSE-SU-2020:2908-1, SUSE-SU-2020:2999-1, SUSE-SU-2020:3014-1, SUSE-SU-2020:3501-1, SUSE-SU-2020:3503-1, SUSE-SU-2020:3532-1, SUSE-SU-2020:3544-1, SUSE-SU-2021:14630-1, USN-4657-1, USN-4658-1, USN-4658-2, USN-4660-1, USN-4660-2, VIGILANCE-VUL-33321.

Description of the vulnerability 

An attacker can trigger a buffer overflow via fbcon_redraw_softback() of the Linux kernel, in order to trigger a denial of service, and possibly to run code.
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This cybersecurity alert impacts software or systems such as Debian, Linux, openSUSE Leap, Slackware, SUSE Linux Enterprise Desktop, SLES, Ubuntu.

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

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

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a technician ability can exploit this security weakness.

Solutions for this threat 

Linux kernel: version 5.8.10.
The version 5.8.10 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v5.x/

Linux kernel: version 5.4.66.
The version 5.4.66 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v5.x/

Linux kernel: version 4.19.146.
The version 4.19.146 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v4.x/

Linux kernel: version 4.14.199.
The version 4.14.199 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.14.199.tar.xz

Linux kernel: version 4.9.237.
The version 4.9.237 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.9.237.tar.xz

Linux kernel: version 4.4.237.
The version 4.4.237 is fixed:
  https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.4.237.tar.xz

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

Debian 9: new linux-4.19 packages (28/09/2020).
New packages are available:
  Debian 9: linux-4.19 4.19.146-1~deb9u1

Debian 9: new linux packages.
New packages are available:
  Debian 9: linux 4.9.240-2

openSUSE Leap 15.1: new kernel packages (12/10/2020).
New packages are available:
  openSUSE Leap 15.1: kernel 4.12.14-lp151.28.71.1

openSUSE Leap 15.2: new kernel packages (02/10/2020).
New packages are available:
  openSUSE Leap 15.2: kernel 5.3.18-lp152.44.1

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

Slackware 14.2: new kernel packages (22/10/2020).
New packages are available:
  Slackware 14.2: kernel 4.4.240-i586-1

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 packages (13/10/2020).
New packages are available:
  SUSE LE 12 SP5: kernel 4.12.14-122.41.1

SUSE LE 12 SP5: new kerne-rt packages.
New packages are available:
  SUSE LE 12 SP5: kernel-rt 4.12.14-10.19.1

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 (13/10/2020).
New packages are available:
  SUSE LE 15 SP1: kernel-azure 4.12.14-8.47.1

SUSE LE 15 SP1: new kernel packages.
New packages are available:
  SUSE LE 15 SP1: kernel 4.12.14-197.61.1

SUSE LE 15 SP1: new kernel-rt packages (23/10/2020).
New packages are available:
  SUSE LE 15 SP1: kernel-rt 4.12.14-14.36.1

SUSE LE 15 SP2: new kernel-azure packages (13/10/2020).
New packages are available:
  SUSE LE 15 SP2: kernel-azure 5.3.18-18.21.1

SUSE LE 15 SP2: new kernel packages (09/10/2020).
New packages are available:
  SUSE LE 15 SP2: kernel 5.3.18-24.24.1

Ubuntu: new linux-image-4.15.0 packages.
New packages are available:
  Ubuntu 14.04 ESM: linux-image-azure 4.15.0.1100.75
  Ubuntu 16.04 LTS: linux-image-generic-hwe-16.04 4.15.0.128.127
  Ubuntu 18.04 LTS: linux-image-generic 4.15.0.128.115

Ubuntu: new linux-image-4.4.0 packages (02/12/2020).
New packages are available:
  Ubuntu 14.04 ESM: linux-image-generic-lpae-lts-xenial 4.4.0.197.172
  Ubuntu 16.04 LTS: linux-image-generic 4.4.0.197.203

Ubuntu: new linux-image-5.4.0 packages.
New packages are available:
  Ubuntu 18.04 LTS: linux-image-generic-hwe-18.04 5.4.0.58.64~18.04.53
  Ubuntu 20.04 LTS: linux-image-generic 5.4.0.58.61

Wind River Linux: version 10.18.44.20.
The version 10.18.44.20 is fixed:
  https://support2.windriver.com/index.php?page=cve&on=list&show=50&product_id=1&product_version%5B0%5D=23&id_status%5B0%5D=4&cve_id_filter=&s=&submit=&order_by=cve_modified_date&order_way=desc#list
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