Linux Kernel iommu AMD wait_on_sem() BusyWait Softlockup
CVE-2026-43253 Published on May 6, 2026
iommu/amd: move wait_on_sem() out of spinlock
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.
Products Associated with CVE-2026-43253
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Affected Versions
Linux:- Version 4bf5beef578e46393f11eb69dda7d17a065e05ff and below f2f65b28d802a667119147444ec2ae33eebf9a58 is affected.
- Version 4bf5beef578e46393f11eb69dda7d17a065e05ff and below 715c263119fd1b918a9fcbd8a36ea5b604a46324 is affected.
- Version 4bf5beef578e46393f11eb69dda7d17a065e05ff and below e15768e68820142077bbca402d8e902f64ade1b0 is affected.
- Version 4bf5beef578e46393f11eb69dda7d17a065e05ff and below 496269d12072ecb219826485bdbec70c92a8eef5 is affected.
- Version 4bf5beef578e46393f11eb69dda7d17a065e05ff and below d2a0cac10597068567d336e85fa3cbdbe8ca62bf is affected.
- Version 4.9 is affected.
- Before 4.9 is unaffected.
- Version 6.6.128, <= 6.6.* is unaffected.
- Version 6.12.75, <= 6.12.* is unaffected.
- Version 6.18.16, <= 6.18.* is unaffected.
- Version 6.19.6, <= 6.19.* is unaffected.
- Version 7.0, <= * is unaffected.