CONFIG_IOMMU_DEBUG_PAGEALLOC: Debug IOMMU mappings against page allocations

General informations

The Linux kernel configuration item CONFIG_IOMMU_DEBUG_PAGEALLOC:

• prompt: Debug IOMMU mappings against page allocations
• type: bool
• depends on: CONFIG_DEBUG_PAGEALLOC && CONFIG_IOMMU_API && CONFIG_PAGE_EXTENSION
• defined in drivers/iommu/Kconfig
• found in Linux kernels: 7.0-rc+HEAD

Help text

This enables a consistency check between the kernel page allocator and the IOMMU subsystem. It verifies that pages being allocated or freed are not currently mapped in any IOMMU domain.

This helps detect DMA use-after-free bugs where a driver frees a page but forgets to unmap it from the IOMMU, potentially allowing a device to overwrite memory that the kernel has repurposed.

These checks are best-effort and may not detect all problems.

Due to performance overhead, this feature is disabled by default. You must enable "iommu.debug_pagealloc" from the kernel command line to activate the runtime checks.

If unsure, say N.

Hardware

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The data is retrived from:

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• Linux Kernel Driver DataBase (LKDDb)

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