CVE-2022-50714
Description
A flaw was discovered in the mt76/mt7921e Wi-Fi driver in the Linux kernel where improper handling of driver data during module removal can lead to a crash. Under certain insmod/rmmod stress test conditions, the driver’s mt7921_pci_remove() function is called while the associated mt76_dev (driver private data) has not been properly initialized or is missing. When the workqueue cancellation logic attempts to access this uninitialized data, it triggers a KASAN BUG: user-memory-access, resulting in a kernel panic or hang.
Mitigation
To mitigate this issue, if the `mt7921e` Wi-Fi hardware is not in use, prevent the `mt7921e` kernel module from loading. This can be achieved by blacklisting the module.
Create a file named `/etc/modprobe.d/blacklist-mt7921e.conf` with the following content:
blacklist mt7921e
After creating the file, regenerate the initramfs and reboot the system for the changes to take effect:
bash
dr_acutereboot
Warning: Blacklisting this module may disable Wi-Fi functionality if your system relies on the mt7921e driver.
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 | 4.7 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability,Integrity,Other
Technical Impact: Other
Initial variables usually contain junk, which can not be trusted for consistency. This can lead to denial of service conditions, or modify control flow in unexpected ways. In some cases, an attacker can "pre-initialize" the variable using previous actions, which might enable code execution. This can cause a race condition if a lock variable check passes when it should not.
Authorization,Other
Technical Impact: Other
Strings that are not initialized are especially dangerous, since many functions expect a null at the end -- and only at the end -- of a string.
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