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Tue, 15 Oct 2024 13:31:38 +0000 (GMT) Received: from nasanex01c.na.qualcomm.com (nasanex01c.na.qualcomm.com [10.45.79.139]) by NASANPPMTA01.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 49FDVb8S015831 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 15 Oct 2024 13:31:37 GMT Received: from [10.216.56.224] (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; Tue, 15 Oct 2024 06:31:33 -0700 Message-ID: Date: Tue, 15 Oct 2024 19:01:30 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] iommu/arm-smmu: Defer probe of clients after smmu device bound Content-Language: en-US To: CC: , , , , , , , , , , , , Prakash Gupta References: <20241004090428.2035-1-quic_pbrahma@quicinc.com> From: Pratyush Brahma In-Reply-To: <20241004090428.2035-1-quic_pbrahma@quicinc.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) 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: D576OjrQQ18vkOw66nyELqYH4K7rmAq7 X-Proofpoint-ORIG-GUID: D576OjrQQ18vkOw66nyELqYH4K7rmAq7 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 clxscore=1015 malwarescore=0 adultscore=0 impostorscore=0 mlxscore=0 priorityscore=1501 suspectscore=0 bulkscore=0 phishscore=0 spamscore=0 mlxlogscore=999 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2410150092 On 10/4/2024 2:34 PM, Pratyush Brahma wrote: > 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. > > Fixes: 021bb8420d44 ("iommu/arm-smmu: Wire up generic configuration support") > Cc: stable@vger.kernel.org > Co-developed-by: Prakash Gupta > Signed-off-by: Prakash Gupta > Signed-off-by: Pratyush Brahma > --- > Changes in v2: > Fix kernel test robot warning > Add stable kernel list in cc > Link to v1: https://lore.kernel.org/all/20241001055633.21062-1-quic_pbrahma@quicinc.com/ > > drivers/iommu/arm/arm-smmu/arm-smmu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c > index 723273440c21..7c778b7eb8c8 100644 > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c > @@ -1437,6 +1437,9 @@ 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 ERR_PTR(dev_err_probe(dev, -EPROBE_DEFER, > + "smmu dev has not bound yet\n")); > } > > ret = -EINVAL; Hi Can someone please review this patch? Let me know if any further information is required. Thanks Pratyush