UBUNTU-CVE-2026-23067
In the Linux kernel, the following vulnerability has been resolved: iommu/io-pgtable-arm: fix size_t signedness bug in unmap path __arm_lpae_unmap() returns size_t but was returning -ENOENT (negative error code) when encountering an unmapped PTE. Since size_t is unsigned, -ENOENT (typically -2) becomes a huge positive value (0xFFFFFFFFFFFFFFFE on 64-bit systems). This corrupted value propagates through the call chain: __arm_lpae_unmap() returns -ENOENT as size_t -> arm_lpae_unmap_pages() returns it -> __iommu_unmap() adds it to iova address -> iommu_pgsize() triggers BUG_ON due to corrupted iova This can cause IOVA address overflow in __iommu_unmap() loop and trigger BUG_ON in iommu_pgsize() from invalid address alignment. Fix by returning 0 instead of -ENOENT. The WARN_ON already signals the error condition, and returning 0 (meaning "nothing unmapped") is the correct semantic for size_t return type. This matches the behavior of other io-pgtable implementations (io-pgtable-arm-v7s, io-pgtable-dart) which return 0 on error conditions.
02 / AFFECTED SOFTWARE
Affected packages
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03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
In the Linux kernel, the following vulnerability has been resolved: iommu/io-pgtable-arm: fix size_t signedness bug in unmap path __arm_lpae_unmap() returns size_t but was returning -ENOENT (negative error code) when encountering an unmapped PTE. Since size_t is unsigned, -ENOENT (typically -2) becomes a huge positive value (0xFFFFFFFFFFFFFFFE on 64-bit systems). This corrupted value propagates through the call chain: __arm_lpae_unmap() returns -ENOENT as size_t -> arm_lpae_unmap_pages() returns it -> __iommu_unmap() adds it to iova address -> iommu_pgsize() triggers BUG_ON due to corrupted iova This can cause IOVA address overflow in __iommu_unmap() loop and trigger BUG_ON in iommu_pgsize() from invalid address alignment. Fix by returning 0 instead of -ENOENT. The WARN_ON already signals the error condition, and returning 0 (meaning "nothing unmapped") is the correct semantic for size_t return type. This matches the behavior of other io-pgtable implementations (io-pgtable-arm-v7s, io-pgtable-dart) which return 0 on error conditions.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/374e7af67d9d9d6103c2cfc8eb32abfecf3a2fd8
- https://git.kernel.org/stable/c/374e7af67d9d9d6103c2cfc8eb32abfecf3a2fd8
- https://git.kernel.org/stable/c/41ec6988547819756fb65e94fc24f3e0dddf84ac
- https://ubuntu.com/security/CVE-2026-23067
- https://ubuntu.com/security/notices/USN-8570-1
- https://ubuntu.com/security/notices/USN-8570-2
- https://ubuntu.com/security/notices/USN-8594-1
- https://ubuntu.com/security/notices/USN-8604-1
- https://ubuntu.com/security/notices/USN-8605-1
- https://www.cve.org/CVERecord?id=CVE-2026-23067