Re: [PATCH 2/2] iommu/vt-d: Fix possible use-after-free of private domain

[Alex Williamson]

On Tue,  6 Aug 2019 08:14:09 +0800
Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote:

> Multiple devices might share a private domain. One real example
> is a pci bridge and all devices behind it. When remove a private
> domain, make sure that it has been detached from all devices to
> avoid use-after-free case.
> 
> Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
> Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Fixes: 942067f1b6b97 ("iommu/vt-d: Identify default domains replaced with private")
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> ---

Tested-by: Alex Williamson <alex.williamson@xxxxxxxxxx>

>  drivers/iommu/intel-iommu.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index 37259b7f95a7..12d094d08c0a 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -4791,7 +4791,8 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info)
>  
>  	/* free the private domain */
>  	if (domain->flags & DOMAIN_FLAG_LOSE_CHILDREN &&
> -	    !(domain->flags & DOMAIN_FLAG_STATIC_IDENTITY))
> +	    !(domain->flags & DOMAIN_FLAG_STATIC_IDENTITY) &&
> +	    list_empty(&domain->devices))
>  		domain_exit(info->domain);
>  
>  	free_devinfo_mem(info);