HIGH Introduced in 6.0
kvm s390 AIBV OOB
CVE-2026-80891
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
01Description
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: pci: Validate AIBV and AISB before pinning guest pages The AIBV holds one bit per MSI-X vector for a given function. The size of the bit vector is derived from the NOI and the AIBVO. If the size of the AIBV exceeds a single page boundary, then reject the request as we cannot safely pin the guest AIBV. Similarly reject the request if the AISB address is not 8-byte aligned as the architecture requires doubleword alignment for the summary bit address. Since the AISBO can address up to 64 bits, the size of the AISB can only be 8 bytes for the function. This also ensures the AISB doesn't exceed a single page boundary.
02KernelScan AI Analysis
Risk summary
A guest VM on s390 systems can trigger an out-of-bounds write by providing a malformed AIBV or AISB configuration to the KVM PCI interrupt forwarding path. This allows a malicious guest to corrupt host kernel memory, potentially leading to host compromise or denial of service.
Vulnerability analysis
The KVM s390 PCI interrupt forwarding code accepts guest-supplied AIBV and AISB addresses and sizes without validating that the AIBV fits within a single page or that the AISB is properly aligned. A malicious guest can supply an AIBV whose computed size crosses a page boundary, causing the host to pin and access memory beyond the intended page, or an unaligned AISB address that violates architecture requirements. The fix adds validation to reject requests where the AIBV would span more than one page or the AISB is not 8-byte aligned before any guest pages are pinned. This is reachable from a guest VM on s390 hardware with PCI passthrough configured.
03Fix Versions
| Branch | Introduced | Fixed in | Patch commit |
|---|---|---|---|
| 6.1 | 6.0 | 6.1.183 | 3a1c64220ede |
| 6.6 | 6.0 | 6.6.151 | f00ef8efd414 |
| 6.12 | 6.0 | 6.12.103 | 15df7700dd99 |
| 6.18 | 6.0 | 6.18.44 | b878ba7e2814 |
| 7.1 | 6.0 | 7.1.8 | fbfe683f8b1a |
| mainline | 6.0 | 7.2 | 868d32ac72cb |