From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1102CCA9EA0 for ; Fri, 25 Oct 2019 10:41:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D84882070B for ; Fri, 25 Oct 2019 10:41:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="jpnQ3Dkj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502510AbfJYKlW (ORCPT ); Fri, 25 Oct 2019 06:41:22 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:45996 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2502503AbfJYKlV (ORCPT ); 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Fri, 25 Oct 2019 10:41:18 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 2vu0frbcnp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 25 Oct 2019 10:41:18 +0000 Received: from abhmp0021.oracle.com (abhmp0021.oracle.com [141.146.116.27]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x9PAfHAR016406; Fri, 25 Oct 2019 10:41:17 GMT Received: from mwanda (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Fri, 25 Oct 2019 10:41:17 +0000 Date: Fri, 25 Oct 2019 13:41:11 +0300 From: Dan Carpenter To: rajur@chelsio.com Cc: linux-rdma@vger.kernel.org Subject: [bug report] RDMA/iw_cxgb4: Avoid touch after free error in ARP failure handlers Message-ID: <20191025104111.GA12120@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9420 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=3 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=693 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910250100 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9420 signatures=668684 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=3 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=772 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1908290000 definitions=main-1910250101 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org Hello Raju Rangoju, The patch 1dad0ebeea1c: "RDMA/iw_cxgb4: Avoid touch after free error in ARP failure handlers" from May 15, 2017, leads to the following static checker warning: drivers/infiniband/hw/cxgb4/cm.c:4310 process_work() warn: 'skb' was already freed. drivers/infiniband/hw/cxgb4/cm.c 4289 static void process_work(struct work_struct *work) 4290 { 4291 struct sk_buff *skb = NULL; 4292 struct c4iw_dev *dev; 4293 struct cpl_act_establish *rpl; 4294 unsigned int opcode; 4295 int ret; 4296 4297 process_timedout_eps(); 4298 while ((skb = skb_dequeue(&rxq))) { 4299 rpl = cplhdr(skb); 4300 dev = *((struct c4iw_dev **) (skb->cb + sizeof(void *))); 4301 opcode = rpl->ot.opcode; 4302 4303 if (opcode >= ARRAY_SIZE(work_handlers) || 4304 !work_handlers[opcode]) { 4305 pr_err("No handler for opcode 0x%x.\n", opcode); 4306 kfree_skb(skb); 4307 } else { 4308 ret = work_handlers[opcode](dev, skb); 4309 if (!ret) 4310 kfree_skb(skb); I'm not sure why this warning didn't show up before... :( We added some kfree_skb() calls to _put_ep_safe() and _put_pass_ep_safe(). The thing about kfree_skb() is that it's refcounted so it might not free anything so this could be a false positive. I've looked at the code and it looks like it could be a bug? 4311 } 4312 process_timedout_eps(); 4313 } 4314 } regards, dan carpenter