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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 27C5BC433DB for ; Mon, 4 Jan 2021 20:29:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CCC522225E for ; Mon, 4 Jan 2021 20:29:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727802AbhADU3Z (ORCPT ); Mon, 4 Jan 2021 15:29:25 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44326 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726396AbhADU3X (ORCPT ); Mon, 4 Jan 2021 15:29:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1609792076; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=ZyoiIpH6kZDHPl7NK/RSNTGczl9VjVr3GWY2olZ3kOk=; b=dhW+hnJT28dPbn646/0TWsFLRonF44sPUCiu6RXF9muG4HQDzVGN62mmAl0ughTg/M9GmW 4RirvGq42M5fE47tR1V/uKRKkdekhRUkYx/FGCn9vHRD6HnuxH6IuqcZ6tpBfEQOYwPeNt pmoLEcPETA5dYip6NtUlPxK1yaaci5c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-51-BigQOZF4NlqZ0XWu9Z0Xnw-1; Mon, 04 Jan 2021 15:27:55 -0500 X-MC-Unique: BigQOZF4NlqZ0XWu9Z0Xnw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2AC6B10054FF; Mon, 4 Jan 2021 20:27:54 +0000 (UTC) Received: from localhost (unknown [10.18.25.174]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A86B517250; Mon, 4 Jan 2021 20:27:50 +0000 (UTC) Date: Mon, 4 Jan 2021 15:27:50 -0500 From: Mike Snitzer To: Defang Bo Cc: agk@redhat.com, linux-kernel@vger.kernel.org, dm-devel@redhat.com Subject: Re: dm snap : add sanity checks to snapshot_ctr Message-ID: <20210104202749.GA3721@redhat.com> References: <1608878926-2283057-1-git-send-email-bodefang@126.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1608878926-2283057-1-git-send-email-bodefang@126.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 25 2020 at 1:48am -0500, Defang Bo wrote: > Similar to commit<70de2cbd>,there should be a check for argc and argv to prevent Null pointer dereferencing > when the dm_get_device invoked twice on the same device path with differnt mode. > > Signed-off-by: Defang Bo > --- > drivers/md/dm-snap.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c > index 4668b2c..dccce8b 100644 > --- a/drivers/md/dm-snap.c > +++ b/drivers/md/dm-snap.c > @@ -1258,6 +1258,13 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv) > > as.argc = argc; > as.argv = argv; > + > + if (!strcmp(argv[0], argv[1])) { > + ti->error = "Error setting metadata or data device"; > + r = -EINVAL; > + goto bad; > + } > + > dm_consume_args(&as, 4); > r = parse_snapshot_features(&as, s, ti); > if (r) > -- > 2.7.4 > We already have this later in snapshot_ctr: if (cow_dev && cow_dev == origin_dev) { ti->error = "COW device cannot be the same as origin device"; r = -EINVAL; goto bad_cow; } Which happens before the 2nd dm_get_device() for the cow device. So I'm not seeing how you could experience the NULL pointer you say is possible. Mike