CVE-2025-39829

What the bug is

This warning was triggered during testing on v6.16: notifier callback ftrace_suspend_notifier_call already registered WARNING: CPU: 2 PID: 86 at kernel/notifier.c:23 notifier_chain_register+0x44/0xb0 ... Call Trace: <TASK> blocking_notifier_chain_register+0x34/0x60 register_ftrace_graph+0x330/0x410 ftrace_profile_write+0x1e9/0x340 vfs_write+0xf8/0x420 ? filp_flush+0x8a/0xa0 ? filp_close+0x1f/0x30 ? do_dup2+0xaf/0x160 ksys_write+0x65/0xe0 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x77/0x7f When writing to the function_profile_enabled interface, the notifier was not unregistered after start_graph_tracing failed, causing a warning the next time function_profile_enabled was written. Fixed by adding unregister_pm_notifier in the exception path.

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/trace/fgraph.c

What this is

FUNCTION HOOKS (FTRACE)MAINTAINERS section matched on kernel/trace/fgraph.c · linux-kernel@vger.kernel.org · Maintained

Check it on the machine

grep -wE 'CONFIG_FUNCTION_GRAPH_TRACER|CONFIG_FUNCTION_TRACER|CONFIG_RETHOOK|CONFIG_RING_BUFFER|CONFIG_TRACEPOINTS|CONFIG_TRACE_CLOCK|CONFIG_TRACING' /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, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.

• bookwormYnot built on arm64/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le
• trixieYnot built on arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
• forky, sidYnot built on arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae

Y

built in where it is built at all; some flavours do not build it

Build switches

CONFIG_FUNCTION_GRAPH_TRACER, CONFIG_FUNCTION_TRACER, CONFIG_RETHOOK, CONFIG_RING_BUFFER, CONFIG_TRACEPOINTS, CONFIG_TRACE_CLOCK, CONFIG_TRACING

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

2025-09-16 (13 months ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.15%, higher than 3.5% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

not yet assignedsource

Subsystem

kernel/trace

Upstream fixes

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

Introduced	Fixed in	Commit
2.6.30	6.12.45	2a2deb9f8df7
2.6.30	6.16.5	000aa47a5123
2.6.30	6.17	edede7a6dcd7

Debian advisories