Out-of-bounds Access Vulnerability in AMD IOMMU Implementation

CVE-2026-64186

What is CVE-2026-64186?

The Linux kernel's AMD IOMMU implementation faced a vulnerability wherein improper input parsing could lead to out-of-bounds memory access. Specifically, the variables dbg_mmio_offset and dbg_cap_offset, declared as integers, were susceptible to receiving excessively large values via user input that were converted using kstrtou32_from_user(), potentially resulting in negative integers. Although prior protections existed, including input size checks and type promotion safeguards, this issue required a more effective handling approach. By replacing the input parsing function with kstrtos32_from_user() and implementing explicit checks for negative values, this vulnerability has been addressed to safeguard against potential memory exploitation.

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