CVE-2026-80626

What the bug is

fsl_emb_pmu_del() unconditionally calls put_cpu_var(cpu_hw_events) at the 'out:' label, but only calls the matching get_cpu_var() after the 'i < 0' early-return check. When event->hw.idx is negative the function jumps to 'out:' without having taken get_cpu_var(), and the trailing put_cpu_var() then issues an unmatched preempt_enable(), underflowing preempt_count. On a CONFIG_PREEMPT=y kernel preempt_count would underflow and eventually present as a 'scheduling while atomic' BUG. Move put_cpu_var() to pair with get_cpu_var() so the percpu access is correctly bracketed and the 'out:' label only handles perf_pmu_enable.

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.

arch/powerpc/perf/core-fsl-emb.c

What this is

LINUX FOR POWERPC (32-BIT AND 64-BIT)MAINTAINERS section matched on arch/powerpc/ · linuxppc-dev@lists.ozlabs.org · Supported

Kernel module

none to look for. The file would have gone into core_fsl_emb, and Debian does not compile it into that module, so finding core_fsl_emb in lsmod would say nothing about this CVE.

Check it on the machine

grep -wE 'CONFIG_FSL_EMB_PERF_EVENT|CONFIG_PERF_EVENTS' /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 does not build this code. In 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.

• bookworm, trixie, forky, sidn

n

not enabled on any flavour - this release does not build the code

Build switches

CONFIG_FSL_EMB_PERF_EVENT, CONFIG_PERF_EVENTS

Reads as

all on means the file is compiled; any one off means it is not.

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

2026-08-28 (2 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.22%, higher than 11.6% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

arch/powerpc

Upstream fixes

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

Introduced	Fixed in	Commit
2.6.34	5.10.261	c0c7722308c5
2.6.34	5.15.212	67aeb1eb93d4
2.6.34	6.1.178	9a515e00b001
2.6.34	6.6.145	5397142d60aa
2.6.34	6.12.97	b89477077c83
2.6.34	6.18.40	73711688479d
2.6.34	7.1.5	b504fd953664
2.6.34	7.2	81e3a8603046