CVE-2026-90332

/// Technical description

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, dw_pcie_ep_raise_msi_irq() 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 iAT

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References