From e98137f0a874ab36d0946de4707aa48cb7137d1c Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Mon, 23 Mar 2026 15:56:58 -0600 Subject: [PATCH] vfio/pci: Fix double free in dma-buf feature The error path through vfio_pci_core_feature_dma_buf() ignores its own advice to only use dma_buf_put() after dma_buf_export(), instead falling through the entire unwind chain. In the unlikely event that we encounter file descriptor exhaustion, this can result in an unbalanced refcount on the vfio device and double free of allocated objects. Avoid this by moving the "put" directly into the error path and return the errno rather than entering the unwind chain. Reported-by: Renato Marziano Fixes: 5d74781ebc86 ("vfio/pci: Add dma-buf export support for MMIO regions") Cc: stable@vger.kernel.org Acked-by: Leon Romanovsky Signed-off-by: Alex Williamson Link: https://lore.kernel.org/r/20260323215659.2108191-3-alex.williamson@nvidia.com Reviewed-by: Jason Gunthorpe Signed-off-by: Alex Williamson --- drivers/vfio/pci/vfio_pci_dmabuf.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c index 478beafc6ac3..b1d658b8f7b5 100644 --- a/drivers/vfio/pci/vfio_pci_dmabuf.c +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -301,11 +301,10 @@ int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, */ ret = dma_buf_fd(priv->dmabuf, get_dma_buf.open_flags); if (ret < 0) - goto err_dma_buf; + dma_buf_put(priv->dmabuf); + return ret; -err_dma_buf: - dma_buf_put(priv->dmabuf); err_dev_put: vfio_device_put_registration(&vdev->vdev); err_free_phys: