From patchwork Wed Feb 8 14:34:22 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steffen Maier X-Patchwork-Id: 9562649 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id DFC73601E5 for ; Wed, 8 Feb 2017 14:37:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D0E762849C for ; Wed, 8 Feb 2017 14:37:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C5839284FE; Wed, 8 Feb 2017 14:37:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8C7AB2849C for ; Wed, 8 Feb 2017 14:37:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932987AbdBHOhm (ORCPT ); Wed, 8 Feb 2017 09:37:42 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49684 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751932AbdBHOhk (ORCPT ); Wed, 8 Feb 2017 09:37:40 -0500 Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v18EZ7MR054531 for ; Wed, 8 Feb 2017 09:35:56 -0500 Received: from e06smtp15.uk.ibm.com (e06smtp15.uk.ibm.com [195.75.94.111]) by mx0a-001b2d01.pphosted.com with ESMTP id 28g1rw91y6-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 08 Feb 2017 09:35:56 -0500 Received: from localhost by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Bottomley" , "Martin K . Petersen" Cc: linux-scsi@vger.kernel.org, linux-s390@vger.kernel.org, Martin Schwidefsky , Heiko Carstens , Steffen Maier , "#2 . 6 . 38+" Subject: [PATCH] zfcp: fix use-after-free by not tracing WKA port open/close on failed send Date: Wed, 8 Feb 2017 15:34:22 +0100 X-Mailer: git-send-email 2.8.4 X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17020814-0020-0000-0000-00000302C244 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17020814-0021-0000-0000-0000405212C1 Message-Id: <20170208143422.64943-1-maier@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-02-08_10:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702080143 Sender: linux-scsi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Dan Carpenter kindly reported: The patch d27a7cb91960: "zfcp: trace on request for open and close of WKA port" from Aug 10, 2016, leads to the following static checker warning: drivers/s390/scsi/zfcp_fsf.c:1615 zfcp_fsf_open_wka_port() warn: 'req' was already freed. drivers/s390/scsi/zfcp_fsf.c 1609 zfcp_fsf_start_timer(req, ZFCP_FSF_REQUEST_TIMEOUT); 1610 retval = zfcp_fsf_req_send(req); 1611 if (retval) 1612 zfcp_fsf_req_free(req); ^^^ Freed. 1613 out: 1614 spin_unlock_irq(&qdio->req_q_lock); 1615 if (req && !IS_ERR(req)) 1616 zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id); ^^^^^^^^^^^ Use after free. 1617 return retval; 1618 } Same thing for zfcp_fsf_close_wka_port() as well. Rather than relying on req being NULL (or ERR_PTR) for all cases where we don't want to trace or should not trace, simply check retval which is unconditionally initialized with -EIO != 0 and it can only become 0 on successful retval = zfcp_fsf_req_send(req). With that we can also remove the then again unnecessary unconditional initialization of req which was introduced with that earlier commit. Reported-by: Dan Carpenter Suggested-by: Benjamin Block Signed-off-by: Steffen Maier Fixes: d27a7cb91960 ("zfcp: trace on request for open and close of WKA port") Cc: #2.6.38+ Reviewed-by: Benjamin Block Reviewed-by: Jens Remus --- drivers/s390/scsi/zfcp_fsf.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/drivers/s390/scsi/zfcp_fsf.c +++ b/drivers/s390/scsi/zfcp_fsf.c @@ -1583,7 +1583,7 @@ out: int zfcp_fsf_open_wka_port(struct zfcp_fc_wka_port *wka_port) { struct zfcp_qdio *qdio = wka_port->adapter->qdio; - struct zfcp_fsf_req *req = NULL; + struct zfcp_fsf_req *req; int retval = -EIO; spin_lock_irq(&qdio->req_q_lock); @@ -1612,7 +1612,7 @@ int zfcp_fsf_open_wka_port(struct zfcp_f zfcp_fsf_req_free(req); out: spin_unlock_irq(&qdio->req_q_lock); - if (req && !IS_ERR(req)) + if (!retval) zfcp_dbf_rec_run_wka("fsowp_1", wka_port, req->req_id); return retval; } @@ -1638,7 +1638,7 @@ static void zfcp_fsf_close_wka_port_hand int zfcp_fsf_close_wka_port(struct zfcp_fc_wka_port *wka_port) { struct zfcp_qdio *qdio = wka_port->adapter->qdio; - struct zfcp_fsf_req *req = NULL; + struct zfcp_fsf_req *req; int retval = -EIO; spin_lock_irq(&qdio->req_q_lock); @@ -1667,7 +1667,7 @@ int zfcp_fsf_close_wka_port(struct zfcp_ zfcp_fsf_req_free(req); out: spin_unlock_irq(&qdio->req_q_lock); - if (req && !IS_ERR(req)) + if (!retval) zfcp_dbf_rec_run_wka("fscwp_1", wka_port, req->req_id); return retval; }