CVE-2020-11869
Description
An integer overflow flaw was found in QEMU in the way it implemented the ATI VGA emulation. This flaw occurs in the ati_2d_blt() routine while handling MMIO write operations through ati_mm_write() callback. A malicious guest could abuse this flaw to crash the QEMU process, resulting in a denial of service.
Statement
This flaw did not affect the following versions of QEMU as they did not include support for ATI VGA emulation:
qemu-kvm-maas shipped with Red Hat Enterprise Linux 7.qemu-kvm-rhevas shipped with Red Hat Virtualization and Red Hat OpenStack.qemu-kvmas shipped with Red Hat Enterprise Linux 6, 7 and 8.
ATI VGA emulation feature was introduced in QEMU upstream version v4.0.0.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 2.8 | 3.3 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | Low | Low | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:L
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
Acknowledgements
Red Hat would like to thank Ziming Zhang for reporting this issue.
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