CVE-2026-64476: In the Linux kernel, the following vulnerability has been resolved: vfio/pci: Latch disable_idle_d3 per device When disable_idle_d3 was introduced i...

Description

In the Linux kernel, the following vulnerability has been resolved: vfio/pci: Latch disable_idle_d3 per device When disable_idle_d3 was introduced in vfio-pci, it directly manipulated the device power state with pci_set_power_state(). There were no refcounts to maintain or balanced operations, we could unconditionally bring the device to D0 and conditionally move it to D3hot. Therefore the module parameter was made writable. Later, in commit c61302aa48f7 ("vfio/pci: Move module parameters to vfio_pci.c"), as part of the vfio-pci-core split, the writable aspect of the module parameter was nullified. The parameter value could still be changed through sysfs, but the vfio-pci driver latched the values into vfio-pci-core globals at module init. Loading the vfio-pci module, or unloading and reloading, with non-default or different values could change the globals relative to existing devices bound to vfio-pci variant drivers. Runtime PM was introduced in commit 7ab5e10eda02 ("vfio/pci: Move the unused device into low power state with runtime PM"), which marks the point where power states became refcounted. PM get and put operations need to be balanced, but the same module operations noted above can change the global variables relative to those devices already bound to vfio-pci variant drivers. This introduces a window where PM operations can now become unbalanced. To resolve this with a narrow footprint for stable backports, the disable_idle_d3 flag is latched into the vfio_pci_core_device at the time of initialization, such that the device always operates with a consistent value. NB. vfio_pci_dev_set_try_reset() now unconditionally raises the runtime PM usage count around bus reset to account for disable_idle_d3 becoming a per-device rather than global flag. When this flag is set, the additional get/put pair is harmless and allows continued use of the shared vfio_pci_dev_set_pm_runtime_get() helper.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 7ab5e10eda02da1d9562ffde562c51055d368e9c, < 332d785f9ae426eeeb92527872adf09d84101ba3; >= 7ab5e10eda02da1d9562ffde562c51055d368e9c, < 654710ef3135c4546b20a903bc23a51b0c44d6c8; >= 7ab5e10eda02da1d9562ffde562c51055d368e9c, < b98296816d31441b307ef9fa8670dcf5a55e5505; >= 7ab5e10eda02da1d9562ffde562c51055d368e9c, < f6c67cf0051f96ba61d186731d3d9409b9927db2; >= 7ab5e10eda02da1d9562ffde562c51055d368e9c, < 062b820290bcb9778e43a73597df76e9bb08acfb; >= 7ab5e10eda02da1d9562ffde562c51055d368e9c, < 4575e9aac5336d1365138c0284773bf8da4b1fa3
Linux	Linux	5.19

References

Timeline

Published: Jul 25, 2026
Last Modified: Jul 25, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-64476?

In the Linux kernel, the following vulnerability has been resolved: vfio/pci: Latch disable_idle_d3 per device When disable_idle_d3 was introduced in vfio-pci, it directly manipulated the device power state with pci_set_power_state(). There were no refcounts to maintain or balanced operations, we could unconditionally bring the device to D0 and conditionally move it to D3hot. Therefore the module parameter was made writable. Later, in commit c61302aa48f7 ("vfio/pci: Move module parameters to vfio_pci.c"), as part of the vfio-pci-core split, the writable aspect of the module parameter was nullified. The parameter value could still be changed through sysfs, but the vfio-pci driver latched the values into vfio-pci-core globals at module init. Loading the vfio-pci module, or unloading and reloading, with non-default or different values could change the globals relative to existing devices bound to vfio-pci variant drivers. Runtime PM was introduced in commit 7ab5e10eda02 ("vfio/pci: Move the unused device into low power state with runtime PM"), which marks the point where power states became refcounted. PM get and put operations need to be balanced, but the same module operations noted above can change the global variables relative to those devices already bound to vfio-pci variant drivers. This introduces a window where PM operations can now become unbalanced. To resolve this with a narrow footprint for stable backports, the disable_idle_d3 flag is latched into the vfio_pci_core_device at the time of initialization, such that the device always operates with a consistent value. NB. vfio_pci_dev_set_try_reset() now unconditionally raises the runtime PM usage count around bus reset to account for disable_idle_d3 becoming a per-device rather than global flag. When this flag is set, the additional get/put pair is harmless and allows continued use of the shared vfio_pci_dev_set_pm_runtime_get() helper.

How severe is CVE-2026-64476?

Severity scoring for CVE-2026-64476 is pending analysis.

How do I fix CVE-2026-64476?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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