From: Alex Williamson <alex.williamson@redhat.com>
To: Tomasz Nowicki <tomasz.nowicki@caviumnetworks.com>
Cc: joro@8bytes.org, robin.murphy@arm.com, will.deacon@arm.com,
lorenzo.pieralisi@arm.com, bhelgaas@google.com,
Jayachandran.Nair@cavium.com, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org,
Ganapatrao.Kulkarni@cavium.com, mw@semihalf.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V1 1/1] iommu: Make sure device's ID array elements are unique
Date: Tue, 19 Dec 2017 09:37:26 -0700 [thread overview]
Message-ID: <20171219093726.432e16e7@t450s.home> (raw)
In-Reply-To: <1513696821-32291-1-git-send-email-tomasz.nowicki@caviumnetworks.com>
On Tue, 19 Dec 2017 16:20:21 +0100
Tomasz Nowicki <tomasz.nowicki@caviumnetworks.com> wrote:
> While iterating over DMA aliases for a PCI device, for some rare cases
> (i.e. PCIe-to-PCI/X bridges) we may get exactly the same ID as initial child
> device. In turn, the same ID may get registered for a device multiple times.
> Eventually IOMMU driver may try to configure the same ID within domain
> multiple times too which for some IOMMU drivers is illegal and causes kernel
> panic.
>
> Rule out ID duplication prior to device ID array registration.
>
> CC: stable@vger.kernel.org # v4.14+
You've identified a release, is there a specific commit this fixes?
> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@caviumnetworks.com>
> ---
> drivers/iommu/iommu.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 3de5c0b..9b2c138 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1945,6 +1945,31 @@ void iommu_fwspec_free(struct device *dev)
> }
> EXPORT_SYMBOL_GPL(iommu_fwspec_free);
>
> +static void iommu_fwspec_remove_ids_dup(struct device *dev, u32 *ids,
> + int *num_ids)
> +{
> + struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> + int i, j, k, valid_ids = *num_ids;
> +
> + for (i = 0; i < valid_ids; i++) {
> + for (j = 0; j < fwspec->num_ids; j++) {
> + if (ids[i] != fwspec->ids[j])
> + continue;
> +
> + dev_info(dev, "found 0x%x ID duplication, skipped\n",
> + ids[i]);
> +
> + for (k = i + 1; k < valid_ids; k++)
> + ids[k - 1] = ids[k];
Use memmove()?
> +
> + valid_ids--;
> + break;
At this point ids[i] is not the ids[i] that we tested for dupes, it's
what was ids[i + 1], but we're going to i++ on the next iteration and
we therefore never test that entry.
> + }
> + }
> +
> + *num_ids = valid_ids;
> +}
> +
> int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids)
> {
> struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> @@ -1954,6 +1979,9 @@ int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids)
> if (!fwspec)
> return -EINVAL;
>
> + /* Rule out IDs already registered */
> + iommu_fwspec_remove_ids_dup(dev, ids, &num_ids);
> +
> size = offsetof(struct iommu_fwspec, ids[fwspec->num_ids + num_ids]);
> if (size > sizeof(*fwspec)) {
> fwspec = krealloc(dev->iommu_fwspec, size, GFP_KERNEL);
next prev parent reply other threads:[~2017-12-19 16:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-19 15:13 [PATCH V1 0/1] Fix kernel panic caused by device ID duplication presented to the IOMMU Tomasz Nowicki
2017-12-19 15:20 ` [PATCH V1 1/1] iommu: Make sure device's ID array elements are unique Tomasz Nowicki
2017-12-19 16:37 ` Alex Williamson [this message]
2017-12-20 10:28 ` Tomasz Nowicki
2017-12-19 16:34 ` [PATCH V1 0/1] Fix kernel panic caused by device ID duplication presented to the IOMMU Robin Murphy
2017-12-20 10:27 ` Tomasz Nowicki
2017-12-22 11:29 ` Tomasz Nowicki
2017-12-27 19:34 ` Jayachandran C
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