CVE-2022-49772
Description
From CVE.org
In the Linux kernel, the following vulnerability has been resolved: ALSA: usb-audio: Drop snd_BUG_ON() from snd_usbmidi_output_open() snd_usbmidi_output_open() has a check of the NULL port with snd_BUG_ON(). snd_BUG_ON() was used as this shouldn't have happened, but in reality, the NULL port may be seen when the device gives an invalid endpoint setup at the descriptor, hence the driver skips the allocation. That is, the check itself is valid and snd_BUG_ON() should be dropped from there. Otherwise it's confusing as if it were a real bug, as recently syzbot stumbled on it.
Statement
The snd_usbmidi_output_open() function previously included a snd_BUG_ON() assertion for a NULL port pointer. However, such a condition can occur legitimately when a device exposes an invalid USB descriptor (e.g., endpoint setup is missing or incorrect). This patch replaces the BUG_ON with a graceful return of -ENXIO, avoiding misleading kernel warnings or panics. The change prevents unnecessary kernel warning output in cases of non-malicious, invalid USB MIDI device configurations. This improves robustness and avoids confusing debug messages when such devices are connected.
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 | 2.1 | 5.5 | N/A |
| Attack Vector | Physical | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | Low | N/A |
| User Interaction | Required | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | Low | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:P/AC:L/PR:N/UI:R/S:U/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:H
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