From patchwork Wed Mar 8 15:05:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Weinberger X-Patchwork-Id: 13165991 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 D10EBC742A7 for ; Wed, 8 Mar 2023 15:06:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230211AbjCHPG0 (ORCPT ); Wed, 8 Mar 2023 10:06:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231718AbjCHPGK (ORCPT ); Wed, 8 Mar 2023 10:06:10 -0500 Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D6463BA874 for ; Wed, 8 Mar 2023 07:06:02 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 771BE6081100; Wed, 8 Mar 2023 16:06:00 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id LA_Cgx6NjAPV; Wed, 8 Mar 2023 16:06:00 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by lithops.sigma-star.at (Postfix) with ESMTP id 2CB7D6418F4F; Wed, 8 Mar 2023 16:06:00 +0100 (CET) Received: from lithops.sigma-star.at ([127.0.0.1]) by localhost (lithops.sigma-star.at [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id CqnZoB0OBev0; Wed, 8 Mar 2023 16:06:00 +0100 (CET) Received: from lithops.sigma-star.at (lithops.sigma-star.at [195.201.40.130]) by lithops.sigma-star.at (Postfix) with ESMTP id 10CFC6418F2B; Wed, 8 Mar 2023 16:06:00 +0100 (CET) Date: Wed, 8 Mar 2023 16:05:59 +0100 (CET) From: Richard Weinberger To: linux-nfs Cc: trond.myklebust@hammerspace.com, chris chilvers Message-ID: <1497292229.221220.1678287959937.JavaMail.zimbra@nod.at> Subject: mountd: Possible bug in next_mnt() MIME-Version: 1.0 X-Originating-IP: [195.201.40.130] X-Mailer: Zimbra 8.8.12_GA_3807 (ZimbraWebClient - FF97 (Linux)/8.8.12_GA_3809) Thread-Index: 9BMFbQ13uvU7jVXUa76Mw87Q1yrJGg== Thread-Topic: mountd: Possible bug in next_mnt() Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Hi! next_mnt() finds submounts below a given path p. While investigating into an issue in my crossmount patches for nfs-utils I noticed that it does not work when fsid=root, rootdir=/some/path/ and then "/" is being exported. In this case next_mnt() is asked to find submounts of "/" but returns none. In my opinion this wrong because every mount is a submount of "/". The following change fixes the problem on my side but I'm not sure whether "/" is a special case in mountd where next_mnt() has to bail out. Comments? :-) Thanks, //richard diff --git a/support/export/cache.c b/support/export/cache.c index 2497d4f48df3..be20cb34adcb 100644 --- a/support/export/cache.c +++ b/support/export/cache.c @@ -410,13 +410,13 @@ static char *next_mnt(void **v, char *p) *v = f; } else f = *v; - while ((me = getmntent(f)) != NULL && l > 1) { + while ((me = getmntent(f)) != NULL && l >= 1) { char *mnt_dir = nfsd_path_strip_root(me->mnt_dir); if (!mnt_dir) continue; - if (strncmp(mnt_dir, p, l) == 0 && mnt_dir[l] == '/') + if (strncmp(mnt_dir, p, l) == 0 && (l == 1 || mnt_dir[l] == '/')) return mnt_dir; } endmntent(f);