From patchwork Wed Nov 16 11:19:55 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Udipto Goswami X-Patchwork-Id: 625425 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1886C4332F for ; Wed, 16 Nov 2022 11:32:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238393AbiKPLbv (ORCPT ); Wed, 16 Nov 2022 06:31:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238402AbiKPLbY (ORCPT ); Wed, 16 Nov 2022 06:31:24 -0500 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7427258031 for ; Wed, 16 Nov 2022 03:20:24 -0800 (PST) Received: from pps.filterd (m0279865.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 2AGAKFCw006564; Wed, 16 Nov 2022 11:20:19 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h=from : to : cc : subject : date : message-id : mime-version : content-type; s=qcppdkim1; bh=X07qs3NSYdOveJAk8kpnYCDf737Sez6YQS9vVFprtdY=; b=ctLmGxTqGNdnblfNBSazxkcnsiFT0v2e6swL8+pnvCruf2DNpYVNnXlWgeLD0wvxw+xn BfXJIsdf6gQdSvTusr/q3dxvtJxnEMKruXXSWFeG9txHSeYIXJNxX40DyIVK2twPCtbH zhm2Vf8W5KNPh2Q49iKMi65xt6faANYpper/Xt6ISGultuMUTYTfzQOtcTp9RoLzzwOj nT/XBGhV6e01x4y0gbFUNsxMtwnsSRiRjEt9z7dxGrCGcyHbNIa6K65+pObpbMfGaDFD e6w5XsXdEeXoTz5fTpAHNs0I+579wrN+b4fQb4XIlQKuQl1Q/O2NlRk6jIe1pk3JNz3m 8g== Received: from nalasppmta05.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3kvx0y06vs-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 16 Nov 2022 11:20:19 +0000 Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA05.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 2AGBKIYm006671 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 16 Nov 2022 11:20:18 GMT Received: from hu-ugoswami-hyd.qualcomm.com (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.29; Wed, 16 Nov 2022 03:20:16 -0800 From: Udipto Goswami To: Greg Kroah-Hartman , , John Keeping CC: Jack Pham , Pratham Pratap , Wesley Cheng , "Udipto Goswami" Subject: [v2] usb: gadget: f_fs: Prevent race between functionfs_unbind & ffs_ep0_queue_wait Date: Wed, 16 Nov 2022 16:49:55 +0530 Message-ID: <20221116111955.21057-1-quic_ugoswami@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 nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: nVQwpJpx6Sy9vMXjrDUcXZe9K6KtYmp3 X-Proofpoint-ORIG-GUID: nVQwpJpx6Sy9vMXjrDUcXZe9K6KtYmp3 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-16_02,2022-11-16_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 spamscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 malwarescore=0 phishscore=0 bulkscore=0 adultscore=0 lowpriorityscore=0 mlxscore=0 mlxlogscore=512 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2210170000 definitions=main-2211160080 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org While performing fast composition switch, there is a possibility that the process of ffs_ep0_write/ffs_ep0_read get into a race condition due to ep0req being freed up from functionfs_unbind. Consider the scenario that the ffs_ep0_write calls the ffs_ep0_queue_wait by taking a lock &ffs->ev.waitq.lock. However, the functionfs_unbind isn't bounded so it can go ahead and mark the ep0req to NULL, and since there is no NULL check in ffs_ep0_queue_wait we will end up in use-after-free. Fix this by making a serialized execution between the two functions using a mutex_lock(ffs->mutex). Also, dequeue the ep0req to ensure that no other function can use it after the free operation. Fixes: ddf8abd25994 ("USB: f_fs: the FunctionFS driver") Signed-off-by: Udipto Goswami --- v2: Replaces spinlock with mutex & added dequeue operation in unbind. drivers/usb/gadget/function/f_fs.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 73dc10a77cde..1439449df39a 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -279,6 +279,9 @@ static int __ffs_ep0_queue_wait(struct ffs_data *ffs, char *data, size_t len) struct usb_request *req = ffs->ep0req; int ret; + if (!req) + return -EINVAL; + req->zero = len < le16_to_cpu(ffs->ev.setup.wLength); spin_unlock_irq(&ffs->ev.waitq.lock); @@ -1892,10 +1895,14 @@ static void functionfs_unbind(struct ffs_data *ffs) ENTER(); if (!WARN_ON(!ffs->gadget)) { + mutex_lock(&ffs->mutex); + /* dequeue before freeing ep0req */ + usb_ep_dequeue(ffs->gadget->ep0, ffs->ep0req); usb_ep_free_request(ffs->gadget->ep0, ffs->ep0req); ffs->ep0req = NULL; ffs->gadget = NULL; clear_bit(FFS_FL_BOUND, &ffs->flags); + mutex_unlock(&ffs->mutex); ffs_data_put(ffs); } }