From: Alex Williamson Date: Fri, 17 Apr 2026 20:27:57 +0000 (-0600) Subject: vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=670e8864b1a218d72f08db40d0103adf38fa1d9b;p=thirdparty%2Fkernel%2Fstable.git vfio/cdx: Serialize VFIO_DEVICE_SET_IRQS with a per-device mutex vfio_cdx_set_msi_trigger() reads vdev->config_msi and operates on the vdev->cdx_irqs array based on its value, but provides no serialization against concurrent VFIO_DEVICE_SET_IRQS ioctls. Two callers can race such that one observes config_msi as set while another clears it and frees cdx_irqs via vfio_cdx_msi_disable(), resulting in a use-after-free of the cdx_irqs array. Add a cdx_irqs_lock mutex to struct vfio_cdx_device and acquire it in vfio_cdx_set_msi_trigger(), which is the single chokepoint through which all updates to config_msi, cdx_irqs, and msi_count flow, covering both the ioctl path and the close-device cleanup path. This keeps the test of config_msi atomic with the subsequent enable, disable, or trigger operations. Drop the pre-call !cdx_irqs test from vfio_cdx_irqs_cleanup() as part of this change: the optimization it provided is redundant with the !config_msi early-return inside vfio_cdx_msi_disable(), and leaving the test in place would be an unsynchronized read of state the new lock is meant to protect. Fixes: 848e447e000c ("vfio/cdx: add interrupt support") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-7 Signed-off-by: Alex Williamson Acked-by: Nikhil Agarwal Link: https://lore.kernel.org/r/20260417202800.88287-3-alex.williamson@nvidia.com Signed-off-by: Alex Williamson --- diff --git a/drivers/vfio/cdx/intr.c b/drivers/vfio/cdx/intr.c index c0eed065e8ef..6dfe0ced3bdd 100644 --- a/drivers/vfio/cdx/intr.c +++ b/drivers/vfio/cdx/intr.c @@ -152,6 +152,8 @@ static int vfio_cdx_set_msi_trigger(struct vfio_cdx_device *vdev, if (start + count > cdx_dev->num_msi) return -EINVAL; + guard(mutex)(&vdev->cdx_irqs_lock); + if (!count && (flags & VFIO_IRQ_SET_DATA_NONE)) { vfio_cdx_msi_disable(vdev); return 0; @@ -210,12 +212,5 @@ int vfio_cdx_set_irqs_ioctl(struct vfio_cdx_device *vdev, /* Free All IRQs for the given device */ void vfio_cdx_irqs_cleanup(struct vfio_cdx_device *vdev) { - /* - * Device does not support any interrupt or the interrupts - * were not configured - */ - if (!vdev->cdx_irqs) - return; - vfio_cdx_set_msi_trigger(vdev, 0, 0, 0, VFIO_IRQ_SET_DATA_NONE, NULL); } diff --git a/drivers/vfio/cdx/main.c b/drivers/vfio/cdx/main.c index 8ab97405b2bd..b31ed4be7bdc 100644 --- a/drivers/vfio/cdx/main.c +++ b/drivers/vfio/cdx/main.c @@ -8,6 +8,23 @@ #include "private.h" +static int vfio_cdx_init_dev(struct vfio_device *core_vdev) +{ + struct vfio_cdx_device *vdev = + container_of(core_vdev, struct vfio_cdx_device, vdev); + + mutex_init(&vdev->cdx_irqs_lock); + return 0; +} + +static void vfio_cdx_release_dev(struct vfio_device *core_vdev) +{ + struct vfio_cdx_device *vdev = + container_of(core_vdev, struct vfio_cdx_device, vdev); + + mutex_destroy(&vdev->cdx_irqs_lock); +} + static int vfio_cdx_open_device(struct vfio_device *core_vdev) { struct vfio_cdx_device *vdev = @@ -273,6 +290,8 @@ static int vfio_cdx_mmap(struct vfio_device *core_vdev, static const struct vfio_device_ops vfio_cdx_ops = { .name = "vfio-cdx", + .init = vfio_cdx_init_dev, + .release = vfio_cdx_release_dev, .open_device = vfio_cdx_open_device, .close_device = vfio_cdx_close_device, .ioctl = vfio_cdx_ioctl, diff --git a/drivers/vfio/cdx/private.h b/drivers/vfio/cdx/private.h index 172e48caa3a0..94374b5fc989 100644 --- a/drivers/vfio/cdx/private.h +++ b/drivers/vfio/cdx/private.h @@ -6,6 +6,8 @@ #ifndef VFIO_CDX_PRIVATE_H #define VFIO_CDX_PRIVATE_H +#include + #define VFIO_CDX_OFFSET_SHIFT 40 static inline u64 vfio_cdx_index_to_offset(u32 index) @@ -31,6 +33,7 @@ struct vfio_cdx_region { struct vfio_cdx_device { struct vfio_device vdev; struct vfio_cdx_region *regions; + struct mutex cdx_irqs_lock; struct vfio_cdx_irq *cdx_irqs; u32 flags; #define BME_SUPPORT BIT(0)