lkml.org 
[lkml]   [2022]   [Oct]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] iommu/vt-d: Add sanity check to iommu_sva_bind_device()
On Fri, Oct 14, 2022 at 09:52:44AM +0800, Baolu Lu wrote:
> On 2022/10/13 23:33, Jerry Snitselaar wrote:
> > iommu_sva_bind_device() should only be called if
> > iommu_dev_enable_feature() succeeded. There has been one case already
> > where that hasn't been the case, which resulted in a null pointer
> > deref in dev_iommu_ops(). To avoid that happening in the future if
> > another driver makes that mistake, sanity check dev->iommu and
> > dev->iommu->iommu_dev prior to calling dev_iommu_ops().
> >
> > Cc: Joerg Roedel <joro@8bytes.org>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: Robin Murphy <robin.murphy@arm.com>
> > Cc: Lu Baolu <baolu.lu@linux.intel.com>
> > Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
> > ---
> > drivers/iommu/iommu.c | 10 +++++++++-
> > 1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 4893c2429ca5..20ec75667529 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -2746,7 +2746,15 @@ iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
> > {
> > struct iommu_group *group;
> > struct iommu_sva *handle = ERR_PTR(-EINVAL);
> > - const struct iommu_ops *ops = dev_iommu_ops(dev);
> > + const struct iommu_ops *ops;
> > +
> > + if (!dev->iommu || !dev->iommu->iommu_dev) {
> > + dev_warn(dev, "%s called without checking succes of iommu_dev_enable_feature?\n",
> > + __func__);
> > + return ERR_PTR(-ENODEV);
> > + }
>
> If that's the case, dev_iommu_ops() will warn a NULL pointer reference.
> This kind of error will be discovered at the first place.
>
> Best regards,
> baolu
>

It will warn this by crashing the system (example from back when idxd had the problem):

[ 21.423729] BUG: kernel NULL pointer dereference, address: 0000000000000038
[ 21.445108] #PF: supervisor read access in kernel mode
[ 21.450912] #PF: error_code(0x0000) - not-present page
[ 21.456706] PGD 0
[ 21.459047] Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 21.464004] CPU: 0 PID: 1420 Comm: kworker/0:3 Not tainted 5.19.0-0.rc3.27.eln120.x86_64 #1
[ 21.464011] Hardware name: Intel Corporation EAGLESTREAM/EAGLESTREAM, BIOS EGSDCRB1.SYS.0067.D12.2110190954 10/19/2021
[ 21.464015] Workqueue: events work_for_cpu_fn
[ 21.464030] RIP: 0010:iommu_sva_bind_device+0x1d/0xe0
[ 21.464046] Code: c3 cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 57 41 56 49 89 d6 41 55 41 54 55 53 48 83 ec 08 48 8b 87 d8 02 00 00 <48> 8b 40 38 48 8b 50 10 48 83 7a 70 00 48 89 14 24 0f 84 91 00 00
[ 21.464050] RSP: 0018:ff7245d9096b7db8 EFLAGS: 00010296
[ 21.464054] RAX: 0000000000000000 RBX: ff1eadeec8a51000 RCX: 0000000000000000
[ 21.464058] RDX: ff7245d9096b7e24 RSI: 0000000000000000 RDI: ff1eadeec8a510d0
[ 21.464060] RBP: ff1eadeec8a51000 R08: ffffffffb1a12300 R09: ff1eadffbfce25b4
[ 21.464062] R10: ffffffffffffffff R11: 0000000000000038 R12: ffffffffc09f8000
[ 21.464065] R13: ff1eadeec8a510d0 R14: ff7245d9096b7e24 R15: ff1eaddf54429000
[ 21.464067] FS: 0000000000000000(0000) GS:ff1eadee7f600000(0000) knlGS:0000000000000000
[ 21.464070] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 21.464072] CR2: 0000000000000038 CR3: 00000008c0e10006 CR4: 0000000000771ef0
[ 21.464074] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 21.464076] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
[ 21.464078] PKRU: 55555554
[ 21.464079] Call Trace:
[ 21.464083] <TASK>
[ 21.464092] idxd_pci_probe+0x259/0x1070 [idxd]
[ 21.464121] local_pci_probe+0x3e/0x80
[ 21.464132] work_for_cpu_fn+0x13/0x20
[ 21.464136] process_one_work+0x1c4/0x380
[ 21.464143] worker_thread+0x1ab/0x380
[ 21.464147] ? _raw_spin_lock_irqsave+0x23/0x50
[ 21.464158] ? process_one_work+0x380/0x380
[ 21.464161] kthread+0xe6/0x110
[ 21.464168] ? kthread_complete_and_exit+0x20/0x20
[ 21.464172] ret_from_fork+0x1f/0x30


It was doing that to SPR systems that didn't boot with
intel_iommu=on. They had to either enable the iommu, or blacklist the
idxd driver until the idxd driver had a fix. The idea here is to
avoid taking the system down, and just have the driver get an error back.

Regards,
Jerry

> > +
> > + ops = dev_iommu_ops(dev);
> > if (!ops->sva_bind)
> > return ERR_PTR(-ENODEV);

\
 
 \ /
  Last update: 2022-10-14 04:11    [W:0.073 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site