GHSA-4589-RC6P-3W23
Vulnerability from github – Published: 2026-09-17 18:32 – Updated: 2026-09-18 18:31In 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 iATU entry that mapped them, which is the same logic the MSI-X path uses.
[mani: commit log]
{
"affected": [],
"aliases": [
"CVE-2026-90332"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-17T17:17:31Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nPCI: dwc: ep: Flush cached MSI write before unmapping the iATU\n\nThe MSI-X path already flushes any posted MSI-X write before tearing down\nits iATU mapping. That was added by commit c22533c66cca (\"PCI: dwc: ep:\nFlush MSI-X write before unmapping its ATU entry\") to make sure the write\nreaches the Root Complex before the outbound window that translates it\ndisappears.\n\nThe MSI path has the same problem but no equivalent flush. When the\nEndpoint driver caches an MSI target address and later observes that the\nRoot Complex has changed it, dw_pcie_ep_raise_msi_irq() unmaps the existing\niATU entry and reprograms it for the new address. Between the last MSI\nwritel() and the unmap there may still be a posted write sitting in the\nfabric, and unmapping the iATU entry can drop or misroute that write.\n\nFix this by reading back from the mapped MSI window before the unmap. The\nreadback drains any posted MSI writes through the same iATU entry that\nmapped them, which is the same logic the MSI-X path uses.\n\n[mani: commit log]",
"id": "GHSA-4589-rc6p-3w23",
"modified": "2026-09-18T18:31:30Z",
"published": "2026-09-17T18:32:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90332"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1b01d725d8b42450b86a857bab3c46856c740166"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/914704c7b318bdaa42dce4e55f6c492190fee3b5"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H",
"type": "CVSS_V3"
}
]
}
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