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Unity Linux 20.1070e Security Update: kernel (UTSA-2025-987652)
medium Nessus Plugin ID 270953
Synopsis
The Unity Linux host is missing one or more security updates.Description
The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2025-987652 advisory.In the Linux kernel, the following vulnerability has been resolved:
mac80211-hwsim: fix late beacon hrtimer handling
Thomas explained in https://lore.kernel.org/r/87mtoeb4hb.ffs@tglx that our handling of the hrtimer here is wrong: If the timer fires late (e.g. due to vCPU scheduling, as reported by Dmitry/syzbot) then it tries to actually rearm the timer at the next deadline, which might be in the past already:
1 2 3 N N+1 | | | ... | |
^ intended to fire here (1) ^ next deadline here (2) ^ actually fired here
The next time it fires, it's later, but will still try to schedule for the next deadline (now 3), etc. until it catches up with N, but that might take a long time, causing stalls etc.
Now, all of this is simulation, so we just have to fix it, but note that the behaviour is wrong even per spec, since there's no value then in sending all those beacons unaligned - they should be aligned to the TBTT (1, 2, 3, ... in the picture), and if we're a bit (or a lot) late, then just resume at that point.
Therefore, change the code to use hrtimer_forward_now() which will ensure that the next firing of the timer would be at N+1 (in the picture), i.e. the next interval point after the current time.
Tenable has extracted the preceding description block directly from the Unity Linux security advisory.
Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.
Solution
Update the affected kernel package.See Also
http://www.nessus.org/u?cc91cde2
Plugin Details
Severity: Medium
ID: 270953
File Name: unity_linux_UTSA-2025-987652.nasl
Version: 1.1
Type: local
Published: 10/21/2025
Updated: 10/21/2025
Supported Sensors: Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.4
CVSS v2
Risk Factor: Medium
Base Score: 4.6
Temporal Score: 3.4
Vector: CVSS2#AV:L/AC:L/Au:S/C:N/I:N/A:C
CVSS Score Source: CVE-2021-47396
CVSS v3
Risk Factor: Medium
Base Score: 5.5
Temporal Score: 4.8
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
Required KB Items: Host/local_checks_enabled, Host/cpu, Host/UOS-Server/release, Host/UOS-Server/rpm-list
Exploit Ease: No known exploits are available
Patch Publication Date: 10/15/2025
Vulnerability Publication Date: 5/21/2024
Reference Information
CVE: CVE-2021-47396