linux-kernel - Re: [PATCH] vfio/xe: Fix use-after-free in xe_vfio_pci_alloc

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Message-ID: <20251228134801.074ed34c.alex@shazbot.org>
Date: Sun, 28 Dec 2025 13:48:01 -0700
From: Alex Williamson <alex@...zbot.org>
To: Alper Ak <alperyasinak1@...il.com>
Cc: michal.winiarski@...el.com, Jason Gunthorpe <jgg@...pe.ca>, Yishai Hadas
 <yishaih@...dia.com>, Shameer Kolothum <skolothumtho@...dia.com>, Kevin
 Tian <kevin.tian@...el.com>, Thomas Hellström
 <thomas.hellstrom@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
 kvm@...r.kernel.org, intel-xe@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vfio/xe: Fix use-after-free in xe_vfio_pci_alloc_file()

On Thu, 25 Dec 2025 18:13:49 +0300
Alper Ak <alperyasinak1@...il.com> wrote:

> migf->filp is accessed after migf has been freed. Save the error
> value before calling kfree() to prevent use-after-free.
> 
> Fixes: 1f5556ec8b9e ("vfio/xe: Add device specific vfio_pci driver variant for Intel graphics")
> Signed-off-by: Alper Ak <alperyasinak1@...il.com>
> ---
>  drivers/vfio/pci/xe/main.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/pci/xe/main.c b/drivers/vfio/pci/xe/main.c
> index 0156b53c678b..8e1595e00e18 100644
> --- a/drivers/vfio/pci/xe/main.c
> +++ b/drivers/vfio/pci/xe/main.c
> @@ -250,6 +250,7 @@ xe_vfio_pci_alloc_file(struct xe_vfio_pci_core_device *xe_vdev,
>  	struct xe_vfio_pci_migration_file *migf;
>  	const struct file_operations *fops;
>  	int flags;
> +	int ret;
>  
>  	migf = kzalloc(sizeof(*migf), GFP_KERNEL_ACCOUNT);
>  	if (!migf)
> @@ -259,8 +260,9 @@ xe_vfio_pci_alloc_file(struct xe_vfio_pci_core_device *xe_vdev,
>  	flags = type == XE_VFIO_FILE_SAVE ? O_RDONLY : O_WRONLY;
>  	migf->filp = anon_inode_getfile("xe_vfio_mig", fops, migf, flags);
>  	if (IS_ERR(migf->filp)) {
> +		ret = PTR_ERR(migf->filp);
>  		kfree(migf);
> -		return ERR_CAST(migf->filp);
> +		return ERR_PTR(ret);
>  	}
>  
>  	mutex_init(&migf->lock);

Applied to vfio for-linus branch for v6.19.  Thanks,

Alex