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CVE-2026-74574
dmaengine: idxd: fix fdev setup failure cleanup in idxd_cdev_open()
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/dma. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-74574 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixedDSA-6466-1 · 2026-08-25 · text | 6.12.105-1 | Update the kernel and reboot. DSA-6466-1 shipped the fix on 2026-08-25, in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
The failed_dev_add and failed_dev_name paths drop the file-device reference while wq->wq_lock is still held. If put_device(fdev) drops the last reference, idxd_file_dev_release() runs synchronously and tries to take wq->wq_lock again, deadlocking. Those paths also fall through into the later ctx cleanup labels even though idxd_file_dev_release() owns that cleanup and frees ctx. This can make idxd_xa_pasid_remove(ctx) and kfree(ctx) operate on a freed context. Move idxd_wq_get() before file-device setup can fail, since the release callback always calls idxd_wq_put(). Then unlock wq->wq_lock before put_device(fdev) and return directly from the file-device setup failure path, leaving ctx cleanup to the release callback.
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/dma/idxd/cdev.c
- What this is
- INTEL IDXD DRIVERMAINTAINERS section matched on drivers/dma/idxd/* · dmaengine@vger.kernel.org · Supported
- Kernel module
- idxd
Check it on the machine
grep -wE 'CONFIG_DMADEVICES|CONFIG_INTEL_IDXD' /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 idxdPrints 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/arm64, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, i386/686, i386/686-pae, i386/rt/686-pae, ppc64el/powerpc64le
- trixieMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- forky, sidMnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt-arm64, armhf/armmp, armhf/armmp-lpae, loong64/loong64, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, riscv64/riscv64, s390x/s390x
- bookworm · linux-6.12Mnot built on amd64/cloud-amd64, arm64/arm64, arm64/arm64-16k, arm64/cloud-arm64, arm64/rt/arm64, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp, ppc64el/powerpc64le, ppc64el/powerpc64le-64k
- M
- a module where it is built at all; some flavours do not build it
- Build switches
- CONFIG_DMADEVICES, CONFIG_INTEL_IDXD
- 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
- 2026-08-15 (2 months 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
- 0.12%, higher than 1.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/dma
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.4 | 6.6.151 | 778ccbded2c8 |
| 6.4 | 6.12.103 | 8d5d28285728 |
| 6.4 | 6.18.44 | 0679c0c189d2 |
| 6.4 | 7.1.8 | 6e26a41c4c1a |
| 6.4 | 7.2 | ee1d72741022 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
| DSA-6466-1 | 2026-08-25 | trixie 6.12.105-1 | 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 flaw is reached only through the local open() syscall on an Intel DSA/IDXD user workqueue character device (/dev/dsa/wq* or /dev/iax/wq*); idxd_cdev_open() is the cdev .open handler and is not reachable from any network-facing kernel service.
- AC:LAttack complexity, low
- An attacker who can open the cdev can reliably hit the failed_dev_name/failed_dev_add cleanup by inducing GFP_KERNEL allocation failures (e.g., memory pressure) during device setup; no race or victim-controlled state beyond that is required.
- PR:LPrivileges required, low
- Exploitation requires only local permission to open the configured user-type DSA workqueue cdev, which on DSA-equipped servers is commonly granted to unprivileged workload/service accounts via udev group ACLs after one-time admin WQ setup, not init-namespace root.
- UI:NUser interaction, none
- The attacker triggers the bug by opening the character device themselves; no additional end-user or administrator interaction is required at exploitation time beyond prior WQ enablement.
- S:UScope, unchanged
- The deadlock, use-after-free, and double-free corrupt kernel/IDXD driver heap state and block the affected workqueue; impact does not cross VM, IOMMU/DMA, or other security boundaries into a separate authority.
- C:HConfidentiality impact, high
- On the error path put_device() synchronously runs idxd_file_dev_release(), which kfree()s ctx while idxd_cdev_open() still references it via filp->private_data, and the fall-through path can call idxd_xa_pasid_remove()/kfree() again—classic kernel heap UAF enabling memory disclosure.
- I:HIntegrity impact, high
- Double-free and use-after-free of the kmalloc-backed idxd_user_context can corrupt slab metadata and be developed into arbitrary kernel memory writes and privilege escalation, not merely a controlled error return.
- A:HAvailability impact, high
- Calling put_device() while holding wq->wq_lock deadlocks when idxd_file_dev_release() re-acquires that mutex, hanging the opener and blocking all other users of the workqueue; heap corruption can additionally panic the kernel.