CVE-2025-39745

rcutorture: Fix rcutorture_one_extend_check() splat in RT kernels

CVE-2025-39745 is fixed in linux on 1 platform by DEBIAN-CVE-2025-39745 (version 6.16.3-1), released September 11, 2025. It is not reported as exploited. Patch Radar priority: Routine.

Routine

CVSS

5.5

medium

Exploitation

None reported

No vendor assessment

CISA KEV

Not listed

Not in the Known Exploited Vulnerabilities catalog

EPSS

0.0016

4th percentile

In the Linux kernel, the following vulnerability has been resolved: rcutorture: Fix rcutorture_one_extend_check() splat in RT kernels For built with CONFIG_PREEMPT_RT=y kernels, running rcutorture tests resulted in the following splat: [ 68.797425] rcutorture_one_extend_check during change: Current 0x1 To add 0x1 To remove 0x0 preempt_count() 0x0 [ 68.797533] WARNING: CPU: 2 PID: 512 at kernel/rcu/rcutorture.c:1993 rcutorture_one_extend_check+0x419/0x560 [rcutorture] [ 68.797601] Call Trace: [ 68.797602] <TASK> [ 68.797619] ? lockdep_softirqs_off+0xa5/0x160 [ 68.797631] rcutorture_one_extend+0x18e/0xcc0 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797646] ? local_clock+0x19/0x40 [ 68.797659] rcu_torture_one_read+0xf0/0x280 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797678] ? __pfx_rcu_torture_one_read+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797804] ? __pfx_rcu_torture_timer+0x10/0x10 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797815] rcu-torture: rcu_torture_reader task started [ 68.797824] rcu-torture: Creating rcu_torture_reader task [ 68.797824] rcu_torture_reader+0x238/0x580 [rcutorture 2466dbd2ff34dbaa36049cb323a80c3306ac997c] [ 68.797836] ? kvm_sched_clock_read+0x15/0x30 Disable BH does not change the SOFTIRQ corresponding bits in preempt_count() for RT kernels, this commit therefore use softirq_count() to check the if BH is disabled.

Where it's fixed

Product	Fixed in	Fix	Released
Linux
linux · Debian 14	6.16.3-1	DEBIAN-CVE-2025-39745	Sep 11, 2025

Details

Published
September 11, 2025
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Vendor advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-39745

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