CVE-2021-20221: Medium severity qemu vulnerability
An out-of-bound heap buffer access via an interrupt ID field resulting from undefined behaviour. The Interrupt ID of the SGI to forward to the specified CPU interfaces. The value of this field is the Interrupt ID, in the range 0-15, for example a value of 0b0011 specifies Interrupt ID 3.
It requires unusual kernel start-up with 'kernel-irqchip=off'.
This issue does not affect default configuration ie. kernel-irqchip=on.
Upstream patch: --------------- -> https://gitlab.com/qemu-project/qemu/-/commit/edfe2eb4360cde4ed5d95bda7777edcb3510f76a
Other sources
An out-of-bounds heap buffer access issue was found in the ARM Generic Interrupt Controller emulator of QEMU up to and including qemu 4.2.0on aarch64 platform. The issue occurs because while writing an interrupt ID to the controller memory area, it is not masked to be 4 bits wide. It may lead to the said issue while updating controller state fields and their subsequent processing. A privileged guest user may use this flaw to crash the QEMU process on the host resulting in DoS scenario.
— Launchpad
Affected Software
Remediation
Patch Available
Patch Available
Event History
Frequently Asked Questions
What is CVE-2021-20221?
CVE-2021-20221 is an out-of-bounds heap buffer access vulnerability in the ARM Generic Interrupt Controller emulator of QEMU.
Which software versions are affected by CVE-2021-20221?
QEMU up to and including version 4.2.0 on the aarch64 platform, Redhat Enterprise Linux 8.0, Debian Debian Linux 9.0 and 10.0.
What is the severity of CVE-2021-20221?
CVE-2021-20221 has a severity rating of medium (6).
How do I fix CVE-2021-20221 for QEMU?
To fix CVE-2021-20221 for QEMU, you should update to version 4.2.1 or later.
Where can I find more information about CVE-2021-20221?
You can find more information about CVE-2021-20221 in the referenced links: [Link 1](https://gitlab.com/qemu-project/qemu/-/commit/edfe2eb4360cde4ed5d95bda7777edcb3510f76a), [Link 2](https://bugzilla.redhat.com/show_bug.cgi/show_bug.cgi?id=1924602), [Link 3](https://bugs.launchpad.net/qemu/+bug/1914353)