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Subject[PATCH] iommu: fix an incorrect NULL check on list iterator
Date
The bug is here:
if (!iommu || iommu->dev->of_node != spec->np) {

The list iterator value 'iommu' will *always* be set and non-NULL by
list_for_each_entry(), so it is incorrect to assume that the iterator
value will be NULL if the list is empty or no element is found (in fact,
it will point to a invalid structure object containing HEAD).

To fix the bug, run insert_iommu_master(dev, &iommu, spec); unlock and
return 0 when found, otherwise unlock and return -ENODEV.

Cc: stable@vger.kernel.org
Fixes: f78ebca8ff3d6 ("iommu/msm: Add support for generic master bindings")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
---
drivers/iommu/msm_iommu.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
index 3a38352b603f..1dbb8b0695ec 100644
--- a/drivers/iommu/msm_iommu.c
+++ b/drivers/iommu/msm_iommu.c
@@ -617,23 +617,17 @@ static int qcom_iommu_of_xlate(struct device *dev,
{
struct msm_iommu_dev *iommu;
unsigned long flags;
- int ret = 0;

spin_lock_irqsave(&msm_iommu_lock, flags);
list_for_each_entry(iommu, &qcom_iommu_devices, dev_node)
- if (iommu->dev->of_node == spec->np)
- break;
-
- if (!iommu || iommu->dev->of_node != spec->np) {
- ret = -ENODEV;
- goto fail;
- }
-
- insert_iommu_master(dev, &iommu, spec);
-fail:
+ if (iommu->dev->of_node == spec->np) {
+ insert_iommu_master(dev, &iommu, spec);
+ spin_unlock_irqrestore(&msm_iommu_lock, flags);
+ return 0;
+ }
spin_unlock_irqrestore(&msm_iommu_lock, flags);

- return ret;
+ return -ENODEV;
}

irqreturn_t msm_iommu_fault_handler(int irq, void *dev_id)
--
2.17.1
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