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.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:NA:H7.5/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H