Bug 2516804 (CVE-2026-74277)

Summary: CVE-2026-74277 kernel: iommu/dma-iommu: Fix wrong scatterlist length assignment in P2PDMA path
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's iommu/dma-iommu component. When handling PCI Peer-to-Peer Direct Memory Access (P2PDMA) cases, an incorrect assignment of the scatterlist length can cause all segments in a multi-segment scatterlist to inherit the length of the first segment. This leads to corrupted DMA lengths, which may result in data corruption during memory transfers.
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Description OSIDB Bzimport 2026-08-15 06:34:20 UTC 
In the Linux kernel, the following vulnerability has been resolved:

iommu/dma-iommu: Fix wrong scatterlist length assignment in P2PDMA path

In iommu_dma_map_sg(), when handling PCI P2PDMA cases, the DMA length
of the current scatterlist segment `s` is incorrectly assigned from the
head entry `sg->length` instead of the current entry `s->length`.

This typo causes all P2PDMA segments in the scatterlist to inherit the
length of the first segment, leading to corrupted DMA lengths for multi-
segment scatterlists.

Fix this by using `s->length` instead of `sg->length`.
Comment 1 Keith Grant 2026-08-20 13:49:37 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081545-CVE-2026-74277-42fb@gregkh/T