CVE-2022-49545
Description
A flaw was found in the Linux kernel's ALSA (Advanced Linux Sound Architecture) USB audio subsystem. This flaw allows a local user to cause a Denial of Service (DoS) through a system crash. A race condition exists when closing a USB MIDI (Musical Instrument Digital Interface) output substream because pending scheduled work is not properly cancelled before the associated runtime object is released. This failure to cancel pending work can result in a use-after-free condition when accessing deallocated memory.
Statement
A use-after-free race condition was found in the Linux kernel's ALSA USB audio subsystem, shipped in Red Hat Enterprise Linux 8 (kernel and kernel-rt). When a USB MIDI output substream is closed, the pending scheduled work is not cancelled before the rawmidi runtime object is released, so the outstanding work can subsequently access the freed memory. A local user with access to a USB MIDI device could use this flaw to cause a denial of service (system crash). Red Hat assessed this flaw as having MODERATE impact (CVSS 3.1 score 5.5, AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), limited to availability; this differs from the upstream CVE.org score of 7.8, which additionally assumes high confidentiality and integrity impact. For the affected Red Hat Enterprise Linux 8 streams the fix has been deferred to a future kernel update, leaving a residual risk of local denial of service on systems that use USB MIDI devices. Red Hat Enterprise Linux 9 and 10 and Red Hat In-Vehicle OS are not affected because the vulnerable code is not present in those releases, and Red Hat Enterprise Linux 6 and 7 are out of support scope.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | 5.5 | 7.8 |
| Attack Vector | Local | Local | Local |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | Low |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | High |
| Integrity Impact | None | None | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Alter Execution Logic; Unexpected State
The main problem is that -- if a lock is overcome -- data could be altered in a bad state.
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