linux-kernel - Re: [PATCH] iommu/vt-d: Clean up si_domain in the init

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Date:   Mon, 10 Oct 2022 07:33:09 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Baolu Lu <baolu.lu@...ux.intel.com>
Cc:     iommu@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
Subject: Re: [PATCH] iommu/vt-d: Clean up si_domain in the init_dmars() error
 path

On Mon, Oct 10, 2022 at 07:32:43PM +0800, Baolu Lu wrote:
> On 2022/10/10 14:56, Jerry Snitselaar wrote:
> > A splat from kmem_cache_destroy() was seen with a kernel prior to
> > commit ee2653bbe89d ("iommu/vt-d: Remove domain and devinfo mempool")
> > when there was a failure in init_dmars(), because the iommu_domain
> > cache still had objects. While the mempool code is now gone, there
> > still is a leak of the si_domain memory if init_dmars() fails. So
> > clean up si_domain in the init_dmars() error path.
> > 
> > Cc: Lu Baolu <baolu.lu@...ux.intel.com>
> > Cc: Joerg Roedel <joro@...tes.org>
> > Cc: Will Deacon <will@...nel.org>
> > Cc: Robin Murphy <robin.murphy@....com>
> > Fixes: 86080ccc223a ("iommu/vt-d: Allocate si_domain in init_dmars()")
> > Signed-off-by: Jerry Snitselaar <jsnitsel@...hat.com>
> > ---
> >   drivers/iommu/intel/iommu.c | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 31bc50e538a3..8f1f80a4d0c5 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -3042,6 +3042,8 @@ static int __init init_dmars(void)
> >   		disable_dmar_iommu(iommu);
> >   		free_dmar_iommu(iommu);
> >   	}
> > +	if (si_domain)
> > +		domain_exit(si_domain);
> 
> Thank you for the patch.
> 
> Above requires si_domain to be NULL or a valid pointer. So do you also
> need to add the following change?
> 
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -2410,6 +2410,7 @@ static int __init si_domain_init(int hw)
> 
>         if (md_domain_init(si_domain, DEFAULT_DOMAIN_ADDRESS_WIDTH)) {
>                 domain_exit(si_domain);
> +               si_domain = NULL;
>                 return -EFAULT;
>         }
> 
> Best regards,
> baolu

Hi Baolu,

Yes. I think should add it after the domain_exit() call I added as well.

Regards,
Jerry