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Unity Linux 20.1050a / 20.1060a / 20.1070a Security Update: kernel (UTSA-2025-394796)
medium Nessus Plugin ID 266871
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-2025-394796 advisory.In the Linux kernel, the following vulnerability has been resolved:
tcp: properly terminate timers for kernel sockets
We had various syzbot reports about tcp timers firing after the corresponding netns has been dismantled.
Fortunately Josef Bacik could trigger the issue more often, and could test a patch I wrote two years ago.
When TCP sockets are closed, we call inet_csk_clear_xmit_timers() to 'stop' the timers.
inet_csk_clear_xmit_timers() can be called from any context, including when socket lock is held.
This is the reason it uses sk_stop_timer(), aka del_timer().
This means that ongoing timers might finish much later.
For user sockets, this is fine because each running timer holds a reference on the socket, and the user socket holds a reference on the netns.
For kernel sockets, we risk that the netns is freed before timer can complete, because kernel sockets do not hold reference on the netns.
This patch adds inet_csk_clear_xmit_timers_sync() function that using sk_stop_timer_sync() to make sure all timers are terminated before the kernel socket is released.
Modules using kernel sockets close them in their netns exit() handler.
Also add sock_not_owned_by_me() helper to get LOCKDEP support : inet_csk_clear_xmit_timers_sync() must not be called while socket lock is held.
It is very possible we can revert in the future commit 3a58f13a881e (net: rds: acquire refcount on TCP sockets) which attempted to solve the issue in rds only.
(net/smc/af_smc.c and net/mptcp/subflow.c have similar code)
We probably can remove the check_net() tests from tcp_out_of_resources() and __tcp_close() in the future.
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.
See Also
http://www.nessus.org/u?da8b66b6
Plugin Details
Severity: Medium
ID: 266871
File Name: unity_linux_UTSA-2025-394796.nasl
Version: 1.1
Type: local
Published: 10/7/2025
Updated: 10/7/2025
Supported Sensors: Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.7
CVSS v2
Risk Factor: Medium
Base Score: 5
Temporal Score: 3.7
Vector: CVSS2#AV:L/AC:H/Au:S/C:P/I:P/A:C
CVSS Score Source: CVE-2024-35910
CVSS v3
Risk Factor: Medium
Base Score: 5.8
Temporal Score: 5.1
Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/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: 7/8/2025
Vulnerability Publication Date: 12/12/2023
Reference Information
CVE: CVE-2024-35910