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iommu/qcom: Fix bogus detach logic

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commit faf305c51a upstream.

Currently, the implementation of qcom_iommu_domain_free() is guaranteed
to do one of two things: WARN() and leak everything, or dereference NULL
and crash. That alone is terrible, but in fact the whole idea of trying
to track the liveness of a domain via the qcom_domain->iommu pointer as
a sanity check is full of fundamentally flawed assumptions. Make things
robust and actually functional by not trying to be quite so clever.

Reported-by: Brian Masney <masneyb@onstation.org>
Tested-by: Brian Masney <masneyb@onstation.org>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Fixes: 0ae349a0f3 ("iommu/qcom: Add qcom_iommu")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Tested-by: Stephan Gerhold <stephan@gerhold.net>
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Robin Murphy 2020-02-18 18:12:41 +00:00 • committed by Greg Kroah-Hartman
commit ef2646fcfc
1 changed files with 12 additions and 16 deletions
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28
drivers/iommu/qcom_iommu.c
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@ -333,21 +333,19 @@ static void qcom_iommu_domain_free(struct iommu_domain *domain)
{
struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
if (WARN_ON(qcom_domain->iommu)) /* forgot to detach? */
return;
iommu_put_dma_cookie(domain);
/* NOTE: unmap can be called after client device is powered off,
* for example, with GPUs or anything involving dma-buf. So we
* cannot rely on the device_link. Make sure the IOMMU is on to
* avoid unclocked accesses in the TLB inv path:
*/
pm_runtime_get_sync(qcom_domain->iommu->dev);
free_io_pgtable_ops(qcom_domain->pgtbl_ops);
pm_runtime_put_sync(qcom_domain->iommu->dev);
if (qcom_domain->iommu) {
/*
* NOTE: unmap can be called after client device is powered
* off, for example, with GPUs or anything involving dma-buf.
* So we cannot rely on the device_link. Make sure the IOMMU
* is on to avoid unclocked accesses in the TLB inv path:
*/
pm_runtime_get_sync(qcom_domain->iommu->dev);
free_io_pgtable_ops(qcom_domain->pgtbl_ops);
pm_runtime_put_sync(qcom_domain->iommu->dev);
}
kfree(qcom_domain);
}
@ -392,7 +390,7 @@ static void qcom_iommu_detach_dev(struct iommu_domain *domain, struct device *de
struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
unsigned i;
if (!qcom_domain->iommu)
if (WARN_ON(!qcom_domain->iommu))
return;
pm_runtime_get_sync(qcom_iommu->dev);
@ -405,8 +403,6 @@ static void qcom_iommu_detach_dev(struct iommu_domain *domain, struct device *de
ctx->domain = NULL;
}
pm_runtime_put_sync(qcom_iommu->dev);
qcom_domain->iommu = NULL;
}
static int qcom_iommu_map(struct iommu_domain *domain, unsigned long iova,