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Date:   Tue, 13 Apr 2021 10:24:14 +1000
From:   David Gibson <david@gibson.dropbear.id.au>
To:     "Christian A. Ehrhardt" <lk@c--e.de>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alex Williamson <alex.williamson@redhat.com>,
        Alexey Kardashevskiy <aik@ozlabs.ru>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Cornelia Huck <cohuck@redhat.com>
Subject: Re: [PATCH] vfio/pci: Add missing range check in vfio_pci_mmap
Message-ID: <YHTkrvXRGrfzJXlv@yekko.fritz.box>
References: <20210410230013.GC416417@lisa.in-ulm.de>
 <20210412140238.184e141f@omen>
 <20210412214124.GA241759@lisa.in-ulm.de>
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On Mon, Apr 12, 2021 at 11:41:24PM +0200, Christian A. Ehrhardt wrote:
>=20
> When mmaping an extra device region verify that the region index
> derived from the mmap offset is valid.
>=20
> Fixes: a15b1883fee1 ("vfio_pci: Allow mapping extra regions")
> Cc: stable@vger.kernel.org
> Signed-off-by: Christian A. Ehrhardt <lk@c--e.de>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  drivers/vfio/pci/vfio_pci.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>=20
> 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)
> =20
>  	index =3D vma->vm_pgoff >> (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT);
> =20
> +	if (index >=3D VFIO_PCI_NUM_REGIONS + vdev->num_regions)
> +		return -EINVAL;
>  	if (vma->vm_end < vma->vm_start)
>  		return -EINVAL;
>  	if ((vma->vm_flags & VM_SHARED) =3D=3D 0)
> @@ -1664,7 +1666,7 @@ static int vfio_pci_mmap(void *device_data, struct =
vm_area_struct *vma)
>  		int regnum =3D index - VFIO_PCI_NUM_REGIONS;
>  		struct vfio_pci_region *region =3D vdev->region + regnum;
> =20
> -		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;

--=20
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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