CVE-2020-11869: 
NixOS vulnerability analysis and mitigation

An integer overflow vulnerability (CVE-2020-11869) was discovered in QEMU's ATI VGA emulation implementation. The vulnerability was reported by Ziming Zhang and disclosed on April 24, 2020. The flaw specifically affects the ati_2d_blt() routine while handling MMIO write operations through the ati_mm_write() callback in the hw/display/ati-2d.c file (Openwall List).

The vulnerability is characterized by an integer overflow in the ATI VGA emulation component of QEMU, specifically in the ati_2d_blt() function. The issue occurs during the processing of MMIO write operations through the ati_mm_write() callback mechanism (Openwall List).

If exploited, this vulnerability could allow a malicious guest to crash the QEMU process, resulting in a denial of service (DoS) condition. The issue particularly affected Ubuntu 20.04 LTS systems (Ubuntu Notice).

The vulnerability can be exploited by a local attacker within a guest environment to cause the QEMU process to crash (Ubuntu Notice).

A patch was released to address this vulnerability and is available in the QEMU repository. Users should update their QEMU packages to the patched versions. For Ubuntu 20.04 users, the fixed version is 1:4.2-3ubuntu6.1. After applying the updates, all QEMU virtual machines need to be restarted to implement the necessary changes (Ubuntu Notice).