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Thu, 18 Jan 2024 09:11:58 GMT Received: from hu-uaggarwa-hyd.qualcomm.com (10.80.80.8) by nasanex01a.na.qualcomm.com (10.52.223.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Thu, 18 Jan 2024 01:11:55 -0800 From: Uttkarsh Aggarwal To: Thinh Nguyen , Greg Kroah-Hartman CC: , , "Uttkarsh Aggarwal" , Subject: [PATCH v2] usb: dwc3: gadget: Fix NULL pointer dereference in dwc3_gadget_suspend Date: Thu, 18 Jan 2024 14:41:46 +0530 Message-ID: <20240118091146.3101-1-quic_uaggarwa@quicinc.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nasanex01a.na.qualcomm.com (10.52.223.231) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: GjPwsHW9zhFdjMXcb2JDo2WNoI80MV2Z X-Proofpoint-GUID: GjPwsHW9zhFdjMXcb2JDo2WNoI80MV2Z X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-01-18_04,2024-01-17_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=1 phishscore=0 lowpriorityscore=1 suspectscore=0 adultscore=0 impostorscore=0 mlxlogscore=659 clxscore=1015 malwarescore=0 priorityscore=1501 spamscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2311290000 definitions=main-2401180065 In current scenario if Plug-out and Plug-In performed continuously there could be a chance while checking for dwc->gadget_driver in dwc3_gadget_suspend, a NULL pointer dereference may occur. Call Stack: CPU1: CPU2: gadget_unbind_driver dwc3_suspend_common dw3_gadget_stop dwc3_gadget_suspend dwc3_disconnect_gadget CPU1 basically clears the variable and CPU2 checks the variable. Consider CPU1 is running and right before gadget_driver is cleared and in parallel CPU2 executes dwc3_gadget_suspend where it finds dwc->gadget_driver which is not NULL and resumes execution and then CPU1 completes execution. CPU2 executes dwc3_disconnect_gadget where it checks dwc->gadget_driver is already NULL because of which the NULL pointer deference occur. Cc: Fixes: 9772b47a4c291 ("usb: dwc3: gadget: Fix suspend/resume during device mode") Signed-off-by: Uttkarsh Aggarwal Acked-by: Thinh Nguyen --- Changes in v2: Added cc and fixes tag missing in v1. Link to v1: https://lore.kernel.org/linux-usb/0ef3fb11-a207-2db4-1714-b3bca2ce2cea@quicinc.com/T/#t drivers/usb/dwc3/gadget.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c index 019368f8e9c4..564976b3e2b9 100644 --- a/drivers/usb/dwc3/gadget.c +++ b/drivers/usb/dwc3/gadget.c @@ -4709,15 +4709,13 @@ int dwc3_gadget_suspend(struct dwc3 *dwc) unsigned long flags; int ret; - if (!dwc->gadget_driver) - return 0; - ret = dwc3_gadget_soft_disconnect(dwc); if (ret) goto err; spin_lock_irqsave(&dwc->lock, flags); - dwc3_disconnect_gadget(dwc); + if (dwc->gadget_driver) + dwc3_disconnect_gadget(dwc); spin_unlock_irqrestore(&dwc->lock, flags); return 0;