Bug 2481960 (CVE-2026-46034)

Summary: CVE-2026-46034 kernel: vfio/cdx: Fix NULL pointer dereference in interrupt trigger path
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's vfio/cdx module. A local user can cause a system crash by improperly configuring Message Signaled Interrupts (MSI) before they are set up. This can lead to a NULL pointer dereference, resulting in a Denial of Service (DoS) for the system.
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Description OSIDB Bzimport 2026-05-27 15:04:24 UTC 
In the Linux kernel, the following vulnerability has been resolved:

vfio/cdx: Fix NULL pointer dereference in interrupt trigger path

Add validation to ensure MSI is configured before accessing cdx_irqs
array in vfio_cdx_set_msi_trigger(). Without this check, userspace
can trigger a NULL pointer dereference by calling VFIO_DEVICE_SET_IRQS
with VFIO_IRQ_SET_DATA_BOOL or VFIO_IRQ_SET_DATA_NONE flags before
ever setting up interrupts via VFIO_IRQ_SET_DATA_EVENTFD.

The vfio_cdx_msi_enable() function allocates the cdx_irqs array and
sets config_msi to 1 only when called through the EVENTFD path. The
trigger loop (for DATA_BOOL/DATA_NONE) assumed this had already been
done, but there was no enforcement of this call ordering.

This matches the protection used in the PCI VFIO driver where
vfio_pci_set_msi_trigger() checks irq_is() before the trigger loop.
Comment 1 Keith Grant 2026-05-27 19:55:55 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026052749-CVE-2026-46034-b4eb@gregkh/T