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Tue, 1 Oct 2024 05:56:57 GMT Received: from hu-pbrahma-hyd.qualcomm.com (10.80.80.8) by nasanex01c.na.qualcomm.com (10.45.79.139) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Mon, 30 Sep 2024 22:56:52 -0700 From: Pratyush Brahma To: CC: , , , , , , , , , , Pratyush Brahma , Prakash Gupta Subject: [PATCH] iommu/arm-smmu: Defer probe of clients after smmu device bound Date: Tue, 1 Oct 2024 11:26:33 +0530 Message-ID: <20241001055633.21062-1-quic_pbrahma@quicinc.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nasanex01c.na.qualcomm.com (10.45.79.139) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: HhDrH_lDxbp9AiQPWo-8IuI2O14j82zF X-Proofpoint-ORIG-GUID: HhDrH_lDxbp9AiQPWo-8IuI2O14j82zF X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-06_09,2024-09-06_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 mlxlogscore=981 impostorscore=0 mlxscore=0 clxscore=1011 priorityscore=1501 adultscore=0 lowpriorityscore=0 suspectscore=0 bulkscore=0 malwarescore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2408220000 definitions=main-2410010038 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240930_225716_646589_2C29C0AA X-CRM114-Status: GOOD ( 14.25 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Null pointer dereference occurs due to a race between smmu driver probe and client driver probe, when of_dma_configure() for client is called after the iommu_device_register() for smmu driver probe has executed but before the driver_bound() for smmu driver has been called. Following is how the race occurs: T1:Smmu device probe T2: Client device probe really_probe() arm_smmu_device_probe() iommu_device_register() really_probe() platform_dma_configure() of_dma_configure() of_dma_configure_id() of_iommu_configure() iommu_probe_device() iommu_init_device() arm_smmu_probe_device() arm_smmu_get_by_fwnode() driver_find_device_by_fwnode() driver_find_device() next_device() klist_next() /* null ptr assigned to smmu */ /* null ptr dereference while smmu->streamid_mask */ driver_bound() klist_add_tail() When this null smmu pointer is dereferenced later in arm_smmu_probe_device, the device crashes. Fix this by deferring the probe of the client device until the smmu device has bound to the arm smmu driver. Co-developed-by: Prakash Gupta Signed-off-by: Prakash Gupta Signed-off-by: Pratyush Brahma Fixes: 021bb8420d44 ("iommu/arm-smmu: Wire up generic configuration support") --- drivers/iommu/arm/arm-smmu/arm-smmu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c index 723273440c21..1f2bafa92f1f 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c @@ -1437,6 +1437,8 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev) goto out_free; } else { smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode); + if (!smmu) + return dev_err_probe(dev, -EPROBE_DEFER, "smmu dev has not bound yet\n"); } ret = -EINVAL;