UBUNTU-CVE-2026-90332: High severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: PCI: dwc: ep: Flush cached MSI write before unmapping the iATU The MSI-X path already flushes any posted MSI-X write before tearing down its iATU mapping. That was added by commit c22533c66cca ("PCI: dwc: ep: Flush MSI-X write before unmapping its ATU entry") to make sure the write reaches the Root Complex before the outbound window that translates it disappears. The MSI path has the same problem but no equivalent flush. When the Endpoint driver caches an MSI target address and later observes that the Root Complex has changed it, dwpcieepraisemsiirq() unmaps the existing iATU entry and reprograms it for the new address. Between the last MSI writel() and the unmap there may still be a posted write sitting in the fabric, and unmapping the iATU entry can drop or misroute that write. Fix this by reading back from the mapped MSI window before the unmap. The readback drains any posted MSI writes through the same iATU entry that mapped them, which is the same logic the MSI-X path uses. [mani: commit log]
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Compensating control
Read back from the mapped MSI window before unmapping the iATU entry to drain any posted MSI writes through the same iATU mapping.
Event History
Frequently Asked Questions
Which systems are most likely to be affected?
Systems using a listed Ubuntu kernel package and a DesignWare PCIe endpoint configuration that raises MSI interrupts are the relevant population. The issue occurs specifically when the Root Complex changes the MSI target address and the endpoint driver remaps its outbound iATU entry.
What condition triggers the failure?
An MSI write must remain posted in the fabric when the endpoint driver unmaps the existing iATU mapping to program a new MSI target address. The unmapped translation window can then cause that pending interrupt write to be dropped or misrouted.
How can the issue be mitigated if an updated kernel is not immediately available?
The provided information does not identify a configuration workaround. Risk is tied to use of the DesignWare PCIe endpoint MSI path and changes to the Root Complex MSI target address.