CVE-2025-68760 – iommu/amd: Fix potential out-of-bounds read in iommu_mmio_show

CVE ID : CVE-2025-68760

Published : Jan. 5, 2026, 9:32 a.m. | 53 minutes ago

Description : 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.

Severity: 0.0 | NA

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