[PATCH 1/1] iommu/arm-smmu-qcom: Fix use-after-free issue in qcom_smmu_create()

[Pratyush Brahma]

Currently, during arm smmu probe, struct arm_smmu_device pointer
is allocated. The pointer is reallocated to a new struct qcom_smmu in
qcom_smmu_create() with devm_krealloc() which frees the smmu device
after copying the data into the new pointer.

The freed pointer is then passed again in devm_of_platform_populate()
inside qcom_smmu_create() which causes a use-after-free issue.

Fix the use-after-free issue by reassigning the old pointer to
the new pointer where the struct was copied by devm_krealloc().

Signed-off-by: Pratyush Brahma <quic_pbrahma@xxxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index ed5ed5da7740..49eaeed6a91c 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -710,6 +710,7 @@ static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,
 	qsmmu = devm_krealloc(smmu->dev, smmu, sizeof(*qsmmu), GFP_KERNEL);
 	if (!qsmmu)
 		return ERR_PTR(-ENOMEM);
+	smmu = &qsmmu->smmu;
 
 	qsmmu->smmu.impl = impl;
 	qsmmu->data = data;
@@ -719,7 +720,7 @@ static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,
 	if (ret)
 		return ERR_PTR(ret);
 
-	return &qsmmu->smmu;
+	return smmu;
 }
 
 /* Implementation Defined Register Space 0 register offsets */
-- 
2.17.1