linux-kernel - Re: [PATCH v3 03/11] iommufd: Introduce IOMMUFD_OBJ

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Zw9ijVgDlvRajsSY@Asurada-Nvidia>
Date: Tue, 15 Oct 2024 23:51:57 -0700
From: Nicolin Chen <nicolinc@...dia.com>
To: Zhangfei Gao <zhangfei.gao@...aro.org>
CC: <jgg@...dia.com>, <kevin.tian@...el.com>, <will@...nel.org>,
	<joro@...tes.org>, <suravee.suthikulpanit@....com>, <robin.murphy@....com>,
	<dwmw2@...radead.org>, <baolu.lu@...ux.intel.com>, <shuah@...nel.org>,
	<linux-kernel@...r.kernel.org>, <iommu@...ts.linux.dev>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kselftest@...r.kernel.org>,
	<eric.auger@...hat.com>, <jean-philippe@...aro.org>, <mdf@...nel.org>,
	<mshavit@...gle.com>, <shameerali.kolothum.thodi@...wei.com>,
	<smostafa@...gle.com>, <yi.l.liu@...el.com>, <aik@....com>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v3 03/11] iommufd: Introduce IOMMUFD_OBJ_VIOMMU and its
 related struct

On Wed, Oct 16, 2024 at 09:56:51AM +0800, Zhangfei Gao wrote:
> On Wed, 16 Oct 2024 at 02:44, Nicolin Chen <nicolinc@...dia.com> wrote:
> >
> > On Mon, Oct 14, 2024 at 07:01:40PM -0700, Nicolin Chen wrote:
> > > On Tue, Oct 15, 2024 at 09:15:01AM +0800, Zhangfei Gao wrote:
> > >
> > > > > > iommufd_device_bind
> > > > > > iommufd_device_attach
> > > > > > iommufd_vdevice_alloc_ioctl
> > > > > >
> > > > > > iommufd_device_detach
> > > > > > iommufd_device_unbind // refcount check fail
> > > > > > iommufd_vdevice_destroy ref--
> > > > >
> > > > > Things should be symmetric. As you suspected, vdevice should be
> > > > > destroyed before iommufd_device_detach.
> > > >
> > > > I am trying based on your for_iommufd_viommu_p2-v3 branch, do you have
> > > > this issue?
> > > > In checking whether close fd before unbind?
> > >
> > > Oops, my bad. I will provide a fix.
> >
> > This should fix the problem:
> >
> > ---------------------------------------------------------------------
> > diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> > index 5fd3dd420290..13100cfea29d 100644
> > --- a/drivers/iommu/iommufd/device.c
> > +++ b/drivers/iommu/iommufd/device.c
> > @@ -277,6 +277,11 @@ EXPORT_SYMBOL_NS_GPL(iommufd_ctx_has_group, IOMMUFD);
> >   */
> >  void iommufd_device_unbind(struct iommufd_device *idev)
> >  {
> > +       mutex_lock(&idev->igroup->lock);
> > +       /* idev->vdev object should be destroyed prior, yet just in case.. */
> > +       if (idev->vdev)
> > +               iommufd_object_remove(idev->ictx, NULL, idev->vdev->obj.id, 0);
> > +       mutex_unlock(&idev->igroup->lock);
> >         iommufd_object_destroy_user(idev->ictx, &idev->obj);
> >  }
> >  EXPORT_SYMBOL_NS_GPL(iommufd_device_unbind, IOMMUFD);
> > ---------------------------------------------------------------------
> 
> Not yet
> [  574.162112] Unable to handle kernel NULL pointer dereference at
> virtual address 0000000000000004
> [  574.261102] pc : iommufd_object_remove+0x7c/0x278
> [  574.265795] lr : iommufd_device_unbind+0x44/0x98
> in check

Hmm, it's kinda odd it crashes inside iommufd_object_remove().
Did you happen to change something there?

The added iommufd_object_remove() is equivalent to userspace
calling the destroy ioctl on the vDEVICE object.

Nicolin