CVE-2026-98282: powerpc/iommu: Fix the overflow validation in iommu_tce_check_ioba
In the Linux kernel, the following vulnerability has been resolved:
powerpc/iommu: Fix the overflow validation in iommutcecheckioba
The commit b1af23d836f8 ("KVM: PPC: iommu: Unify TCE checking") unified IOBA parameter checking across KVM and VFIO into iommutcecheckioba(). While doing so, the passed in argument npages is ignored and constant value '1' is used leaving out a possible overflow as the callers can legitimately be using npages > 1 for HSTUFFTCE or HPUTTCEINDIRECT cases.
Fix this by accounting for 'npages', checking for arithmetic overflow, and verifying that the entire requested range (ioba - offset + npages) does not exceed the table capacity 'size'.
Affected Software
Remediation
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Update powerpc/iommu iommu_tce_check_ioba() to account for npages instead of using constant value 1, check arithmetic overflow, and verify that the full requested range (ioba - offset + npages) does not exceed the table capacity size.
Event History
Frequently Asked Questions
Who is realistically exposed to this issue?
Systems using the Linux kernel on PowerPC with the IOMMU TCE checking path used by KVM or VFIO are the relevant exposure scope. The issue applies when callers use multi-page TCE operations, including H_STUFF_TCE or H_PUT_TCE_INDIRECT.
What does an attacker need to exploit it?
The CVSS vector indicates local access and low privileges are required, with no user interaction. Exploitation depends on being able to invoke the affected IOMMU TCE handling with an npages value greater than 1.
What is the impact of successful exploitation?
The reported CVSS score is 8.8 high, with high confidentiality, integrity, and availability impact. The vulnerability can permit an unchecked overflow or range beyond the IOMMU table capacity during multi-page TCE validation.
How can I tell whether a system needs the fix?
Review the kernel's powerpc/iommu iommu_tce_check_ioba implementation and confirm whether it accounts for the supplied npages value, checks arithmetic overflow, and validates the entire requested range against the table size. Kernels containing the referenced stable commits include the correction.