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Ubuntu Security Notice USN-4945-2
May 19, 2021

linux-raspi, linux-raspi-5.4 vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in the Linux kernel.

Software Description:
- linux-raspi: Linux kernel for Raspberry Pi (V8) systems
- linux-raspi-5.4: Linux kernel for Raspberry Pi (V8) systems

Details:

USN-4945-1 fixed vulnerabilities in the Linux kernel for Ubuntu
20.04 LTS and Ubuntu 18.04 LTS. This update provides the corresponding
Linux kernel updates targeted specifically for Raspberry Pi devices
in those same Ubuntu Releases.

Original advisory details:

It was discovered that the Nouveau GPU driver in the Linux kernel did not
properly handle error conditions in some situations. A local attacker could
use this to cause a denial of service (system crash). (CVE-2020-25639)

Jan Beulich discovered that the Xen netback backend in the Linux kernel did
not properly handle certain error conditions under paravirtualization. An
attacker in a guest VM could possibly use this to cause a denial of service
(host domain crash). (CVE-2021-28038)

It was discovered that the fastrpc driver in the Linux kernel did not
prevent user space applications from sending kernel RPC messages. A local
attacker could possibly use this to gain elevated privileges.
(CVE-2021-28375)

It was discovered that the Realtek RTL8188EU Wireless device driver in the
Linux kernel did not properly validate ssid lengths in some situations. An
attacker could use this to cause a denial of service (system crash).
(CVE-2021-28660)

It was discovered that the USB/IP driver in the Linux kernel contained race
conditions during the update of local and shared status. An attacker could
use this to cause a denial of service (system crash). (CVE-2021-29265)

It was discovered that a race condition existed in the netfilter subsystem
of the Linux kernel when replacing tables. A local attacker could use this
to cause a denial of service (system crash). (CVE-2021-29650)

Arnd Bergmann discovered that the video4linux subsystem in the Linux kernel
did not properly deallocate memory in some situations. A local attacker
could use this to cause a denial of service (memory exhaustion).
(CVE-2021-30002)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 20.04 LTS:
  linux-image-5.4.0-1035-raspi    5.4.0-1035.38
  linux-image-raspi               5.4.0.1035.70
  linux-image-raspi2              5.4.0.1035.70

Ubuntu 18.04 LTS:
  linux-image-5.4.0-1035-raspi    5.4.0-1035.38~18.04.1
  linux-image-raspi-hwe-18.04     5.4.0.1035.37

After a standard system update you need to reboot your computer to make
all the necessary changes.

ATTENTION: Due to an unavoidable ABI change the kernel updates have
been given a new version number, which requires you to recompile and
reinstall all third party kernel modules you might have installed.
Unless you manually uninstalled the standard kernel metapackages
(e.g. linux-generic, linux-generic-lts-RELEASE, linux-virtual,
linux-powerpc), a standard system upgrade will automatically perform
this as well.

References:
  https://ubuntu.com/security/notices/USN-4945-2
  https://ubuntu.com/security/notices/USN-4945-1
  CVE-2020-25639, CVE-2021-28038, CVE-2021-28375, CVE-2021-28660,
  CVE-2021-29265, CVE-2021-29650, CVE-2021-30002

Package Information:
  https://launchpad.net/ubuntu/+source/linux-raspi/5.4.0-1035.38
  https://launchpad.net/ubuntu/+source/linux-raspi-5.4/5.4.0-1035.38~18.04.1