CVE-2026-97925

What the bug is

朱恺乾 reported and decoded the following race condition when a broadcast device is replaced: CPUA CPUB __tick_broadcast_oneshot_control() bc = tick_broadcast_device.evtdev; tick_install_broadcast_device(dev) clockevents_exchange_device(cur, dev) shutdown(cur); detach(cur); cur->handler = noop; tick_broadcast_device.evtdev = dev; tick_broadcast_set_event(bc, next_event); <- FAIL: arms a detached device. If the original broadcast device has a restricted interrupt affinity mask and the last CPU in that mask goes offline then the BUG() in tick_cleanup_dead_cpu() triggers because the clockevent device is not in detached state. The reason for this is that tick_install_broadcast_device() is not serialized vs. tick broadcast operations. The obvious cure is to serialize tick_install_broadcast_device() with tick_broadcast_lock against a concurrent tick broadcast operation. That requires to split clockevents_exchange_device() into two parts, one which does the exchange, shutdown and detach operation and the other which drops the module reference count. This is required because the module reference cannot be dropped while holding tick_broadcast_lock. Let clockevents_exchange_device() do both operations as before, but let the broadcast device code take the two step approach and do the device exchange under tick_broadcast_lock and drop the module reference count after releasing it.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

kernel/time/clockevents.c
kernel/time/tick-broadcast.c
kernel/time/tick-internal.h

What this is

HIGH-RESOLUTION TIMERS, TIMER WHEEL, CLOCKEVENTSMAINTAINERS section matched on kernel/time/clockevents.c · linux-kernel@vger.kernel.org · Maintained

Check it on the machine

grep -w CONFIG_GENERIC_CLOCKEVENTS /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

Show whether Debian builds this, per release

Debian builds this code. Every release below compiles the affected file into the kernels it ships.

• bookworm, trixie, forky, sid, bookworm · linux-6.12y

y

built into the kernel image on every flavour - only a patch removes it

Build switch

CONFIG_GENERIC_CLOCKEVENTS

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Signals

Published

2026-09-25 (24 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.21%, higher than 9.8% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

kernel/time

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
2.6.21	6.1.189	338d6859cd15
2.6.21	6.6.158	757aa9f548c1
2.6.21	6.12.111	3da55616db2b
2.6.21	6.18.53	3525b94b2f25
2.6.21	7.2.7	292b7a8ed840
2.6.21	7.3	113a9796effe

Debian advisories