Re: [PATCH 1/2] vfio/cdx: Fix NULL pointer dereference in interrupt trigger path

[Gupta, Nipun]

On 20-03-2026 15:49, Prasanna Kumar T S M wrote:
> 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.
>
> Fixes: 848e447e000c ("vfio/cdx: add interrupt support")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Prasanna Kumar T S M <ptsm@xxxxxxxxxxxxxxxxxxx>

Acked-by: Nipun Gupta <nipun.gupta@xxxxxxx>