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From: Pratyush Brahma <quic_pbrahma@quicinc.com>
To: <quic_c_gdjako@quicinc.com>
CC: <andersson@kernel.org>, <conor+dt@kernel.org>,
        <devicetree@vger.kernel.org>, <djakov@kernel.org>,
        <iommu@lists.linux.dev>, <joro@8bytes.org>, <konrad.dybcio@linaro.org>,
        <krzysztof.kozlowski+dt@linaro.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-arm-msm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <quic_cgoldswo@quicinc.com>, <quic_pdaly@quicinc.com>,
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        <robdclark@gmail.com>, <robh+dt@kernel.org>, <robin.murphy@arm.com>,
        <will@kernel.org>, Pratyush Brahma <quic_pbrahma@quicinc.com>
Subject: [PATCH 1/1] iommu/arm-smmu-qcom: Fix use-after-free issue in qcom_smmu_create()
Date: Tue, 13 Feb 2024 11:56:08 +0530
Message-ID: <20240213062608.13018-1-quic_pbrahma@quicinc.com>
In-Reply-To: <20240201210529.7728-4-quic_c_gdjako@quicinc.com>
References: <20240201210529.7728-4-quic_c_gdjako@quicinc.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain

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@quicinc.com>
---
 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