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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 5C066C7618B for ; Fri, 26 Jul 2019 09:12:18 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3171C2238C for ; Fri, 26 Jul 2019 09:12:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3171C2238C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:37606 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqwGu-0007Xr-Bm for qemu-devel@archiver.kernel.org; Fri, 26 Jul 2019 05:12:16 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:32903) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hqwGM-0005Le-0U for qemu-devel@nongnu.org; Fri, 26 Jul 2019 05:11:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hqwGG-0005Vw-Kb for qemu-devel@nongnu.org; Fri, 26 Jul 2019 05:11:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58756) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hqwGG-0005PB-AY for qemu-devel@nongnu.org; Fri, 26 Jul 2019 05:11:36 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9EB3581F25 for ; Fri, 26 Jul 2019 09:11:34 +0000 (UTC) Received: from localhost (ovpn-117-212.ams2.redhat.com [10.36.117.212]) by smtp.corp.redhat.com (Postfix) with ESMTP id D86455D9C6; Fri, 26 Jul 2019 09:11:29 +0000 (UTC) From: Stefan Hajnoczi To: virtio-fs@redhat.com, qemu-devel@nongnu.org Date: Fri, 26 Jul 2019 10:11:03 +0100 Message-Id: <20190726091103.23503-6-stefanha@redhat.com> In-Reply-To: <20190726091103.23503-1-stefanha@redhat.com> References: <20190726091103.23503-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 26 Jul 2019 09:11:34 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH 5/5] virtiofsd: prevent races with lo_dirp_put() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Dr. David Alan Gilbert" , Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Introduce lo_dirp_put() so that FUSE_RELEASEDIR does not cause use-after-free races with other threads that are accessing lo_dirp. Also make lo_releasedir() atomic to prevent FUSE_RELEASEDIR racing with itself. This prevents double-frees. Signed-off-by: Stefan Hajnoczi --- contrib/virtiofsd/passthrough_ll.c | 42 +++++++++++++++++++++++++----- 1 file changed, 36 insertions(+), 6 deletions(-) diff --git a/contrib/virtiofsd/passthrough_ll.c b/contrib/virtiofsd/passt= hrough_ll.c index ad3abdd532..f74e7d2d21 100644 --- a/contrib/virtiofsd/passthrough_ll.c +++ b/contrib/virtiofsd/passthrough_ll.c @@ -1293,11 +1293,28 @@ static void lo_readlink(fuse_req_t req, fuse_ino_= t ino) } =20 struct lo_dirp { + gint refcount; DIR *dp; struct dirent *entry; off_t offset; }; =20 +static void lo_dirp_put(struct lo_dirp **dp) +{ + struct lo_dirp *d =3D *dp; + + if (!d) { + return; + } + *dp =3D NULL; + + if (g_atomic_int_dec_and_test(&d->refcount)) { + closedir(d->dp); + free(d); + } +} + +/* Call lo_dirp_put() on the return value when no longer needed */ static struct lo_dirp *lo_dirp(fuse_req_t req, struct fuse_file_info *fi= ) { struct lo_data *lo =3D lo_data(req); @@ -1305,6 +1322,9 @@ static struct lo_dirp *lo_dirp(fuse_req_t req, stru= ct fuse_file_info *fi) =20 pthread_mutex_lock(&lo->mutex); elem =3D lo_map_get(&lo->dirp_map, fi->fh); + if (elem) { + g_atomic_int_inc(&elem->dirp->refcount); + } pthread_mutex_unlock(&lo->mutex); if (!elem) return NULL; @@ -1335,6 +1355,8 @@ static void lo_opendir(fuse_req_t req, fuse_ino_t i= no, struct fuse_file_info *fi d->offset =3D 0; d->entry =3D NULL; =20 + g_atomic_int_set(&d->refcount, 1); /* paired with lo_releasedir() */ + fh =3D lo_add_dirp_mapping(req, d); if (fh =3D=3D -1) goto out_err; @@ -1363,7 +1385,7 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_= t ino, size_t size, off_t offset, struct fuse_file_info *fi, int plus) { struct lo_data *lo =3D lo_data(req); - struct lo_dirp *d; + struct lo_dirp *d =3D NULL; struct lo_inode *dinode; char *buf =3D NULL; char *p; @@ -1451,6 +1473,8 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_= t ino, size_t size, =20 err =3D 0; error: + lo_dirp_put(&d); + // If there's an error, we can only signal it if we haven't stored // any entries yet - otherwise we'd end up with wrong lookup // counts for the entries that are already in the buffer. So we @@ -1477,22 +1501,25 @@ static void lo_readdirplus(fuse_req_t req, fuse_i= no_t ino, size_t size, static void lo_releasedir(fuse_req_t req, fuse_ino_t ino, struct fuse_fi= le_info *fi) { struct lo_data *lo =3D lo_data(req); + struct lo_map_elem *elem; struct lo_dirp *d; =20 (void) ino; =20 - d =3D lo_dirp(req, fi); - if (!d) { + pthread_mutex_lock(&lo->mutex); + elem =3D lo_map_get(&lo->dirp_map, fi->fh); + if (!elem) { + pthread_mutex_unlock(&lo->mutex); fuse_reply_err(req, EBADF); return; } =20 - pthread_mutex_lock(&lo->mutex); + d =3D elem->dirp; lo_map_remove(&lo->dirp_map, fi->fh); pthread_mutex_unlock(&lo->mutex); =20 - closedir(d->dp); - free(d); + lo_dirp_put(&d); /* paired with lo_opendir() */ + fuse_reply_err(req, 0); } =20 @@ -1701,6 +1728,9 @@ static void lo_fsyncdir(fuse_req_t req, fuse_ino_t = ino, int datasync, res =3D fdatasync(fd); else res =3D fsync(fd); + + lo_dirp_put(&d); + fuse_reply_err(req, res =3D=3D -1 ? errno : 0); } =20 --=20 2.21.0