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Mon, 27 May 2019 15:23:23 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3030.oracle.com with ESMTP id 2srbdwdgxc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 27 May 2019 15:23:23 +0000 Received: from abhmp0022.oracle.com (abhmp0022.oracle.com [141.146.116.28]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x4RFNMqM016912; Mon, 27 May 2019 15:23:22 GMT Received: from kadam (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 27 May 2019 08:23:22 -0700 Date: Mon, 27 May 2019 18:23:16 +0300 From: Dan Carpenter To: Jens Axboe Cc: linux-fsdevel@vger.kernel.org Subject: Re: [bug report] io_uring: add support for sqe links Message-ID: <20190527152316.GJ24680@kadam> References: <20190527100808.GA31410@mwanda> <20190527141014.GI24680@kadam> <9b7b794b-26ed-7525-5f81-93cb60e1a005@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9b7b794b-26ed-7525-5f81-93cb60e1a005@kernel.dk> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9269 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905270108 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9269 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905270108 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, May 27, 2019 at 08:34:18AM -0600, Jens Axboe wrote: > On 5/27/19 8:10 AM, Dan Carpenter wrote: > > On Mon, May 27, 2019 at 07:36:22AM -0600, Jens Axboe wrote: > >> On 5/27/19 4:08 AM, Dan Carpenter wrote: > >>> Hello Jens Axboe, > >>> > >>> The patch f3fafe4103bd: "io_uring: add support for sqe links" from > >>> May 10, 2019, leads to the following static checker warning: > >>> > >>> fs/io_uring.c:623 io_req_link_next() > >>> error: potential NULL dereference 'nxt'. > >>> > >>> fs/io_uring.c > >>> 614 static void io_req_link_next(struct io_kiocb *req) > >>> 615 { > >>> 616 struct io_kiocb *nxt; > >>> 617 > >>> 618 nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb, list); > > ^^^^^^^^^^^^^^^ > > If this list is empty then "nxt" is NULL. > > Right... > > >>> 619 list_del(&nxt->list); > >>> ^^^^^^^^^ > >>> The warning is a false positive but this is a NULL dereference. > >>> > >>> 620 if (!list_empty(&req->link_list)) { > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > > > We're checking for list_empty() here. > > After deleting an entry from it. > Ah... Right. Sorry. regards, dan carpenter