CVE-2026-64149

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

dma-mapping: move dma_map_resource() sanity check into debug code

dma_map_resource() uses pfn_valid() to ensure the range is not RAM.

However, pfn_valid() only checks for availability of the memory map for

a PFN but it does not ensure that the PFN is actually backed by RAM. On

ARM64 with SPARSEMEM (128MB section granularity), MMIO addresses that

share a section with RAM will falsely trigger the WARN_ON_ONCE and cause

dma_map_resource() to return DMA_MAPPING_ERROR.

This causes a WARNING on Raspberry Pi 4 during spi_bcm2835 probe because

the SPI FIFO register (0xfe204004) falls in the same sparsemem section

as the end of RAM (0xf8000000-0xfbffffff), both in section 31

(0xf8000000-0xffffffff).

Move the sanity check from dma_map_resource() into debug_dma_map_phys()

and replace the unreliable pfn_valid() with pfn_valid() &&

!PageReserved(), which correctly identifies actual usable RAM without

false positives for MMIO re

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References