Google: sys-kernel/csql-kernel-6_1, sys-kernel/lakitu-kernel-6_1: security update to 18244.521.88

medium Tenable Cloud Security Plugin ID 451189

Description

There are packages installed that are affected by a vulnerability referenced in the following CVE:

- In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Fix VM hard lockup after
prolonged inactivity with periodic HV timer When advancing the target expiration for the guest's APIC
timer in periodic mode, set the expiration to "now" if the target expiration is in the past (similar to
what is done in update_target_expiration()). Blindly adding the period to the previous target expiration
can result in KVM generating a practically unbounded number of hrtimer IRQs due to programming an expired
timer over and over. In extreme scenarios, e.g. if userspace pauses/suspends a VM for an extended
duration, this can even cause hard lockups in the host. Currently, the bug only affects Intel CPUs when
using the hypervisor timer (HV timer), a.k.a. the VMX preemption timer. Unlike the software timer, a.k.a.
hrtimer, which KVM keeps running even on exits to userspace, the HV timer only runs while the guest is
active. As a result, if the vCPU does not run for an extended duration, there will be a huge gap between
the target expiration and the current time the vCPU resumes running. Because the target expiration is
incremented by only one period on each timer expiration, this leads to a series of timer expirations
occurring rapidly after the vCPU/VM resumes. More critically, when the vCPU first triggers a periodic HV
timer expiration after resuming, advancing the expiration by only one period will result in a target
expiration in the past. As a result, the delta may be calculated as a negative value. When the delta is
converted into an absolute value (tscdeadline is an unsigned u64), the resulting value can overflow what
the HV timer is capable of programming. I.e. the large value will exceed the VMX Preemption Timer's
maximum bit width of cpu_preemption_timer_multi + 32, and thus cause KVM to switch from the HV timer to
the software timer (hrtimers). After switching to the software timer, periodic timer expiration callbacks
may be executed consecutively within a single clock interrupt handler, because hrtimers honors KVM's
request for an expiration in the past and immediately re-invokes KVM's callback after reprogramming. And
because the interrupt handler runs with IRQs disabled, restarting KVM's hrtimer over and over until the
target expiration is advanced to "now" can result in a hard lockup. E.g. the following hard lockup was
triggered in the host when running a Windows VM (only relevant because it used the APIC timer in periodic
mode) after resuming the VM from a long suspend (in the host). NMI watchdog: Watchdog detected hard LOCKUP
on cpu 45 ... RIP: 0010:advance_periodic_target_expiration+0x4d/0x80 [kvm] ... RSP: 0018:ff4f88f5d98d8ef0
EFLAGS: 00000046 RAX: fff0103f91be678e RBX: fff0103f91be678e RCX: 00843a7d9e127bcc RDX: 0000000000000002
RSI: 0052ca4003697505 RDI: ff440d5bfbdbd500 RBP: ff440d5956f99200 R08: ff2ff2a42deb6a84 R09:
000000000002a6c0 R10: 0122d794016332b3 R11: 0000000000000000 R12: ff440db1af39cfc0 R13: ff440db1af39cfc0
R14: ffffffffc0d4a560 R15: ff440db1af39d0f8 FS: 00007f04a6ffd700(0000) GS:ff440db1af380000(0000)
knlGS:000000e38a3b8000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000d5651feff8 CR3:
000000684e038002 CR4: 0000000000773ee0 PKRU: 55555554 Call Trace: <IRQ> apic_timer_fn+0x31/0x50 [kvm]
__hrtimer_run_queues+0x100/0x280 hrtimer_interrupt+0x100/0x210 ? ttwu_do_wakeup+0x19/0x160
smp_apic_timer_interrupt+0x6a/0x130 apic_timer_interrupt+0xf/0x20 </IRQ> Moreover, if the suspend duration
of the virtual machine is not long enough to trigger a hard lockup in this scenario, since commit
98c25ead5eda ("KVM: VMX: Move preemption timer <=> hrtimer dance to common x86"), KVM will continue using
the software timer until the guest reprograms the APIC timer in some way. Since the periodic timer does
not require frequent APIC timer register programming, the guest may continue to use the software timer in
---truncated--- (CVE-2025-71104)

Solution

Update the sys-kernel/csql-kernel-6_1 library and its related packages to version 18244.521.88 or later.

Plugin Details

Severity: Medium

ID: 451189

Version: Revision 1.1

Type: Local

Family: Google COS Security Checks

Published: 10/1/2026

Updated: 10/1/2026

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.86

Vendor

Vendor Severity: LOW

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-2025-71104

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

Exploit Ease: No known exploits are available

Vulnerability Publication Date: 1/14/2026

Reference Information

CVE: CVE-2025-71104

Detections

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