Re: [PATCH] vfio/pci: Add missing range check in vfio_pci_mmap

[David Gibson]

On Mon, Apr 12, 2021 at 11:41:24PM +0200, Christian A. Ehrhardt wrote:
> 
> When mmaping an extra device region verify that the region index
> derived from the mmap offset is valid.
> 
> Fixes: a15b1883fee1 ("vfio_pci: Allow mapping extra regions")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Christian A. Ehrhardt <lk@xxxxxxx>

Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>

> ---
>  drivers/vfio/pci/vfio_pci.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 65e7e6b44578..5023e23db3bc 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -1656,6 +1656,8 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
>  
>  	index = vma->vm_pgoff >> (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT);
>  
> +	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
> +		return -EINVAL;
>  	if (vma->vm_end < vma->vm_start)
>  		return -EINVAL;
>  	if ((vma->vm_flags & VM_SHARED) == 0)
> @@ -1664,7 +1666,7 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
>  		int regnum = index - VFIO_PCI_NUM_REGIONS;
>  		struct vfio_pci_region *region = vdev->region + regnum;
>  
> -		if (region && region->ops && region->ops->mmap &&
> +		if (region->ops && region->ops->mmap &&
>  		    (region->flags & VFIO_REGION_INFO_FLAG_MMAP))
>  			return region->ops->mmap(vdev, region, vma);
>  		return -EINVAL;

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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