From: Tony Lindgren <tony@atomide.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>,
Christoph Hellwig <hch@infradead.org>,
Ben Skeggs <bskeggs@redhat.com>,
Kevin Tian <kevin.tian@intel.com>,
Ashok Raj <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Alex Williamson <alex.williamson@redhat.com>,
Eric Auger <eric.auger@redhat.com>, Liu Yi L <yi.l.liu@intel.com>,
Jacob jun Pan <jacob.jun.pan@intel.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Thierry Reding <thierry.reding@gmail.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@lst.de>,
linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
regressions@lists.linux.dev
Subject: Re: [PATCH v4 8/9] iommu: Remove unused argument in is_attach_deferred
Date: Thu, 31 Mar 2022 09:25:20 +0300 [thread overview]
Message-ID: <YkVJUBK5uHl7ELdv@atomide.com> (raw)
In-Reply-To: <20220330173323.GA2120790@nvidia.com>
Hi,
* Jason Gunthorpe <jgg@nvidia.com> [220330 17:31]:
> On Wed, Mar 30, 2022 at 08:19:37PM +0300, Tony Lindgren wrote:
>
> > > > __iommu_probe_device from probe_iommu_group+0x2c/0x38
> > > > probe_iommu_group from bus_for_each_dev+0x74/0xbc
> > > > bus_for_each_dev from bus_iommu_probe+0x34/0x2e8
> > > > bus_iommu_probe from bus_set_iommu+0x80/0xc8
> > > > bus_set_iommu from omap_iommu_init+0x88/0xcc
> > > > omap_iommu_init from do_one_initcall+0x44/0x24c
> > > >
> > > > Any ideas for a fix?
> > > >
> > > > It would be good to fix this quickly so we don't end up with a broken
> > > > v5.18-rc1..
> > > >
> > > > For reference, this is mainline commit 41bb23e70b50 ("iommu: Remove unused
> > > > argument in is_attach_deferred").
> > >
> > > Are you confident in the bisection? I don't see how that commit could
> > > NULL deref..
> >
> > Oops sorry you're right, the breaking commit is a different patch, it's
> > 3f6634d997db ("iommu: Use right way to retrieve iommu_ops") instead. I must
> > have picked the wrong commit while testing.
>
> That makes alot more sense
>
> > > Can you find the code that is the NULL deref?
> >
> > I can debug a bit more tomorrow.
>
> Looks like omap's omap_iommu_probe_device() is buggy, it returns 0 on
> error paths:
>
> num_iommus = of_property_count_elems_of_size(dev->of_node, "iommus",
> sizeof(phandle));
> if (num_iommus < 0)
> return 0;
>
> This function needs to return an errno -ENODEV
>
> Otherwise it causes a NULL dev->iommu->iommu_dev and dev_iommu_ops() will
> crash.
You got it. This fixes the issue for me. Looks like the regression already
happened earlier and recent changes just expose it.
For reference, fix posted at:
https://lore.kernel.org/linux-iommu/20220331062301.24269-1-tony@atomide.com/T/#u
Regards,
Tony
next prev parent reply other threads:[~2022-03-31 6:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-16 2:52 [PATCH v4 0/9] iommu cleanup and refactoring Lu Baolu
2022-02-16 2:52 ` [PATCH v4 1/9] iommu/vt-d: Remove guest pasid related callbacks Lu Baolu
2022-02-16 2:52 ` [PATCH v4 2/9] iommu: Remove guest pasid related interfaces and definitions Lu Baolu
2022-02-16 2:52 ` [PATCH v4 3/9] iommu/vt-d: Remove aux-domain related callbacks Lu Baolu
2022-02-16 2:52 ` [PATCH v4 4/9] iommu: Remove aux-domain related interfaces and iommu_ops Lu Baolu
2022-02-16 2:52 ` [PATCH v4 5/9] iommu: Remove apply_resv_region Lu Baolu
2022-02-16 2:52 ` [PATCH v4 6/9] drm/nouveau/device: Get right pgsize_bitmap of iommu_domain Lu Baolu
2022-02-16 2:52 ` [PATCH v4 7/9] iommu: Use right way to retrieve iommu_ops Lu Baolu
2022-05-04 7:53 ` [bug] NULL pointer deref after 3f6634d997db ("iommu: Use right way to retrieve iommu_ops") Jan Stancek
2022-05-04 11:14 ` Robin Murphy
2022-05-04 11:53 ` Joerg Roedel
2022-05-04 12:08 ` Jan Stancek
2022-05-04 12:11 ` Jason Gunthorpe
2022-02-16 2:52 ` [PATCH v4 8/9] iommu: Remove unused argument in is_attach_deferred Lu Baolu
2022-03-30 14:00 ` Tony Lindgren
2022-03-30 14:23 ` Jason Gunthorpe
2022-03-30 17:19 ` Tony Lindgren
2022-03-30 17:33 ` Jason Gunthorpe
2022-03-31 6:25 ` Tony Lindgren [this message]
2022-03-31 6:40 ` Drew Fustini
2022-02-16 2:52 ` [PATCH v4 9/9] iommu: Split struct iommu_ops Lu Baolu
2022-02-28 12:26 ` [PATCH v4 0/9] iommu cleanup and refactoring Joerg Roedel
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