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CVE-2026-89510
RDMA/cxgb4: Cancel reg_work before freeing device on remove
Published 2026-09-11 (37 days ago) by the Linux kernel CNA. Subsystem drivers/infiniband. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-89510 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 | fixedDLA-4841-1 · 2026-10-17 · text | 6.1.190-1 | Update the kernel and reboot. DLA-4841-1 shipped the fix on 2026-10-17, in 6.1.190-1. A running kernel keeps the old code until the machine restarts. |
| 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
c4iw_uld_state_change() queues reg_work to register the RDMA device. c4iw_remove() can free ctx->dev while this work is pending or running, leaving c4iw_register_device() accessing the freed device. Cancel reg_work before removing the device. The registration work can tear down ctx->dev when registration fails, so do not unregister or deallocate it again in that case. 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/infiniband/hw/cxgb4/device.c
- What this is
- CXGB4 IWARP RNIC DRIVER (IW_CXGB4)MAINTAINERS section matched on drivers/infiniband/hw/cxgb4/ · linux-rdma@vger.kernel.org · Supported
- Kernel module
- iw_cxgb4
Check it on the machine
grep -wE 'CONFIG_INFINIBAND|CONFIG_INFINIBAND_CXGB4' /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.
lsmod | grep -w iw_cxgb4Prints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
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.
- bookwormMnot built on amd64/cloud-amd64, arm64/cloud-arm64
- trixieMnot built on amd64/cloud-amd64, arm64/cloud-arm64, armel/rpi
- forky, sid, bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/cloud-arm64
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_INFINIBAND, CONFIG_INFINIBAND_CXGB4
- 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
- 2026-09-11 (37 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
- 0.18%, higher than 6.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/infiniband
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 4.15 | 5.10.270 | e6e79e7be87c |
| 4.15 | 5.15.221 | 672ee1981db1 |
| 4.15 | 6.1.188 | 4681e731db07 |
| 4.15 | 6.6.157 | 3265d558dfaf |
| 4.15 | 6.12.109 | fe9c591026c5 |
| 4.15 | 6.18.50 | 85f438382a86 |
| 4.15 | 7.2.4 | 320e5258a53a |
| 4.15 | 7.3 | a7100601aa1a |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4841-1 | 2026-10-17 | bookworm 6.1.190-1 | tracker |
| 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 UAF is reached from c4iw_remove() on local Chelsio T4/T5/T6 RDMA teardown (iw_cxgb4 rmmod, PCI sysfs unbind/hot-remove, EEH reset, or ULD STATE_DOWN/DETACH/FATAL). reg_work is queued from local STATE_UP (cxgb_open/uld_attach), not from c4iw_uld_rx_handler packet processing.
- AC:LAttack complexity, low
- An attacker queues c4iw_register_device via STATE_UP (first cxgb_open or iw_cxgb4 load) then immediately runs c4iw_remove via unbind/rmmod/EEH, controlling both sides of the missing cancel_work_sync race and retrying bind/unbind until the worker uses freed ctx->dev; such UAFs score AC:L.
- PR:LPrivileges required, low
- Per CNA driver-removal UAF precedent, an unprivileged local user on Chelsio iWARP/HPC hosts can spray the freed c4iw_dev/ib_device while privileged or automated teardown proceeds; init-namespace root is not required for the UAF itself.
- UI:NUser interaction, none
- No victim action such as mounting a filesystem or opening a file is required; the attacker queues reg_work and coordinates driver removal themselves, or piggybacks on routine PCI/module teardown.
- S:UScope, unchanged
- The use-after-free corrupts the host kernel c4iw_dev/ib_device heap object within the same security authority; it is not a VM escape, IOMMU/DMA isolation bypass, or sandbox breakout.
- C:HConfidentiality impact, high
- After c4iw_dealloc()/ib_dealloc_device(), c4iw_register_device() still reads ctx->dev (node_guid, ports, ibdev ops) from the freed ib_device; this kernel heap UAF enables arbitrary disclosure via slab reuse.
- I:HIntegrity impact, high
- The dangling worker writes ibdev fields, may call ib_register_device() on freed memory, and can double-free via c4iw_dealloc(); heap spraying the ib_device ops table yields write and control-flow hijack primitives.
- A:HAvailability impact, high
- Use-after-free of c4iw_dev from workqueue context during remove causes a kernel oops or panic even when not fully exploited, so availability impact is High.