Bug 2427112 (CVE-2025-68760)

Summary: CVE-2025-68760 kernel: iommu/amd: Fix potential out-of-bounds read in iommu_mmio_show
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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OS: Linux   
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Description OSIDB Bzimport 2026-01-05 10:02:06 UTC 
In the Linux kernel, the following vulnerability has been resolved:

iommu/amd: Fix potential out-of-bounds read in iommu_mmio_show

In iommu_mmio_write(), it validates the user-provided offset with the
check: `iommu->dbg_mmio_offset > iommu->mmio_phys_end - 4`.
This assumes a 4-byte access. However, the corresponding
show handler, iommu_mmio_show(), uses readq() to perform an 8-byte
(64-bit) read.

If a user provides an offset equal to `mmio_phys_end - 4`, the check
passes, and will lead to a 4-byte out-of-bounds read.

Fix this by adjusting the boundary check to use sizeof(u64), which
corresponds to the size of the readq() operation.
Comment 1 Vipul Nair 2026-01-05 12:22:55 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026010551-CVE-2025-68760-5350@gregkh/T