iommu/amd: move wait_on_sem() out of spinlock
Affects Linux kernels using AMD IOMMU with iommu.strict=1, from 4.9 onward. Fixed in 6.6.128, 6.12.75, 6.18.16 and 6.19.6 on their respective branches.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Fix
- Fixed in 6.6.128, 6.12.75, 6.18.16, 6.19.6
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: partial
Summary
In the Linux kernel, the following vulnerability has been resolved: iommu/amd: move wait_on_sem() out of spinlock With iommu.strict=1, the existing completion wait path can cause soft lockups under stressed environment, as wait_on_sem() busy-waits under the spinlock with interrupts disabled. Move the completion wait in iommu_completion_wait() out of the spinlock. wait_on_sem() only polls the hardware-updated cmd_sem and does not require iommu->lock, so holding the lock during the busy wait unnecessarily increases contention and extends the time with interrupts disabled.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: partial
- Record last updated
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
4.9
- KernelLinux
From 4.9.0 · fixed in 6.6.128; From 6.7.0 · fixed in 6.12.75; From 6.13.0 · fixed in 6.18.16; From 6.19.0 · fixed in 6.19.6
References 6
git.kernel.org
Questions about CVE-2026-43253
What does this mean?
The AMD IOMMU completion wait path busy-waits while holding a spinlock with interrupts disabled. Under stressed conditions this can cause soft lockups.Source: git.kernel.org
Am I affected, and how do I check?
Affected kernels range from 4.9.0 up to the fixed release on each branch, and the issue only arises with iommu.strict=1, either set at build time or passed at boot. To check, run uname -r for the kernel version and look for iommu.strict=1 in /proc/cmdline.Source: git.kernel.org
What should I do about it?
Update to the fixed release for the matching branch: 6.6.128, 6.12.75, 6.18.16, or 6.19.6 and later.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data