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CVE-2026-89938
iio: chemical: atlas-sensor: use iio_trigger_poll_nested() to fix remove UAF
Published 2026-09-16 (33 days ago) by the Linux kernel CNA. Subsystem drivers/iio. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-89938 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | fixedDSA-6528-1 · 2026-09-29 · text | 6.12.111-1 | Update the kernel and reboot. DSA-6528-1 shipped the fix on 2026-09-29, in 6.12.111-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.2.6-1 | Update the kernel and reboot. Fixed in 7.2.6-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4817-1 · 2026-10-04 · text | 6.12.111-1~deb12u1 | Update the kernel and reboot. DLA-4817-1 shipped the fix on 2026-10-04, in 6.12.111-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The atlas driver requests its hardware data-ready IRQ with devm_request_threaded_irq(); its threaded handler queues an irq_work, atlas_work_handler(), that calls iio_trigger_poll(data->trig). The IRQ is devm-managed, so free_irq() runs from the devres unwind after atlas_remove() returns without flushing that irq_work. Once a buffer is enabled, conversion-complete IRQs keep firing and queueing it; a pending irq_work can therefore run after the unwind has freed atlas_data/indio_dev and the trigger, when atlas_work_handler() derives the atlas_data pointer via container_of() and dereferences data->trig, a use-after-free. Call iio_trigger_poll_nested() directly from the threaded handler instead of bouncing through irq_work. free_irq() then drains the threaded handler, closing the window; other iio drivers with a threaded data-ready IRQ do the same (e.g. bmi270). This issue was found by an in-house static analysis tool.
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.
drivers/iio/chemical/atlas-sensor.c
- What this is
- IIO SUBSYSTEM AND DRIVERSMAINTAINERS section matched on drivers/iio/ · linux-iio@vger.kernel.org · Maintained
- Kernel module
- none to look for. The file would have gone into atlas_sensor, and Debian does not compile it into that module, so finding atlas_sensor in lsmod would say nothing about this CVE.
Check it on the machine
grep -wE 'CONFIG_ATLAS_PH_SENSOR|CONFIG_IIO' /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 5 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, sid, bookworm · linux-6.12n
- n
- not enabled on any flavour - this release does not build the code
- Build switches
- CONFIG_ATLAS_PH_SENSOR, CONFIG_IIO
- 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
- 2026-09-16 (33 days ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.17%, higher than 6.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/iio
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.8 | 6.6.157 | f64b437641b5 |
| 4.8 | 6.12.110 | 91e12b0fbd70 |
| 4.8 | 6.18.51 | 2071624c3d0f |
| 4.8 | 7.2.5 | 30b0d44c978b |
| 4.8 | 7.3 | be61c8c62526 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4817-1 | 2026-10-04 | bookworm 6.12.111-1~deb12u1 | tracker |
| DSA-6528-1 | 2026-09-29 | trixie 6.12.111-1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- The use-after-free is reached from local IIO sysfs/chardev buffer enable on the Atlas I2C chemical sensor plus driver teardown (sysfs unbind, rmmod, or parent adapter removal). There is no network, Bluetooth, or remote-protocol path into atlas_interrupt_handler or atlas_work_handler.
- AC:LAttack complexity, low
- With the IIO buffer enabled, conversion-complete IRQs keep queueing irq_work every 450-650ms. atlas_remove() never calls irq_work_sync(), so pending work runs after the synchronous devres unwind frees atlas_data. The attacker controls buffer enable and bind/unbind retries; on PREEMPT_RT or CPUs without an irq_work IPI the window is milliseconds.
- PR:LPrivileges required, low
- IIO buffer/enable is mode 0644 with no capability check, and on industrial/IoT water-quality systems that ship Atlas OEM SM sensors those nodes are commonly group-accessible to monitoring services. Per driver-removal UAF scoring, an unprivileged local user can drive the IRQ/irq_work side while teardown proceeds; init-namespace root is not required.
- UI:NUser interaction, none
- The attacker enables the IIO buffer themselves and coordinates driver unbind or module teardown; no separate victim action such as plugging hardware or mounting a filesystem is required.
- S:UScope, unchanged
- The use-after-free corrupts kernel heap objects (atlas_data and the IIO trigger) in the host kernel's own security authority. This is a standard local kernel privilege-escalation path, not a VM, IOMMU, or sandbox boundary crossing.
- C:HConfidentiality impact, high
- atlas_work_handler() recovers freed atlas_data via container_of() and dereferences data->trig. A use-after-free of that sprayable driver-private object yields an arbitrary kernel read primitive, including via iio_trigger_poll() walking attacker-controlled trigger state.
- I:HIntegrity impact, high
- After spraying the freed atlas_data, data->trig is attacker-controlled, so iio_trigger_poll() performs atomic updates and generic_handle_irq() on attacker-chosen IRQ numbers. That is an arbitrary kernel write and control-flow hijack primitive, consistent with use-after-free scoring.
- A:HAvailability impact, high
- The pending irq_work running against freed atlas_data and the IIO trigger causes a kernel oops or panic (KASAN use-after-free or a wild dereference of data->trig), so availability impact is high even without a full exploit.