vfio/xe: Fix use-after-free in xe_vfio_pci_alloc_file()

[PATCH] vfio/xe: Fix use-after-free in xe_vfio_pci_alloc_file()

Posted by Alper Ak 1 month, 1 week ago

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@gmail.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);
-- 
2.43.0

Re: [PATCH] vfio/xe: Fix use-after-free in xe_vfio_pci_alloc_file()

Posted by Alex Williamson 1 month, 1 week ago

On Thu, 25 Dec 2025 18:13:49 +0300
Alper Ak <alperyasinak1@gmail.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@gmail.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