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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 D2D05C43603 for ; Thu, 12 Dec 2019 18:01:30 +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 A2870206DA for ; Thu, 12 Dec 2019 18:01:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ETTNP3Y0" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A2870206DA 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]:35162 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ifSmH-0006qU-5L for qemu-devel@archiver.kernel.org; Thu, 12 Dec 2019 13:01:29 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:35552) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1ifRWu-0007cU-R8 for qemu-devel@nongnu.org; Thu, 12 Dec 2019 11:41:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ifRWt-0004YD-Gk for qemu-devel@nongnu.org; Thu, 12 Dec 2019 11:41:32 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:23706 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ifRWt-0004Wu-Bp for qemu-devel@nongnu.org; Thu, 12 Dec 2019 11:41:31 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576168890; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=YoQGJDV9HoWl44AbZJVj7f1/ZZSuC/LPVu68B+Gd5Yc=; b=ETTNP3Y09LmNzQg7GA+Ll7pJIvNDFsB19nsMoimyJi7My4SnsaxnDVMTqsiVQdn9tCVKn5 V6h/I/TFS+4Ugi2ddUOGZUtZ226tmdJE5YKZiulh/AQL9s3Uo0FOVEWV/5SmO+gTRnT3t1 8LGDOlPwEEhdYqH2dnRqxr8DsP0K2XE= 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-114-zRMH6D_kMlOfEeUo77I8Vw-1; Thu, 12 Dec 2019 11:41:29 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EDD972EDD for ; Thu, 12 Dec 2019 16:41:28 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-116-226.ams2.redhat.com [10.36.116.226]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2133660BE1; Thu, 12 Dec 2019 16:41:27 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com, vgoyal@redhat.com Subject: [PATCH 089/104] virtiofsd: prevent races with lo_dirp_put() Date: Thu, 12 Dec 2019 16:38:49 +0000 Message-Id: <20191212163904.159893-90-dgilbert@redhat.com> In-Reply-To: <20191212163904.159893-1-dgilbert@redhat.com> References: <20191212163904.159893-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: zRMH6D_kMlOfEeUo77I8Vw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: Stefan Hajnoczi 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 --- tools/virtiofsd/passthrough_ll.c | 41 +++++++++++++++++++++++++++----- 1 file changed, 35 insertions(+), 6 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough= _ll.c index eadd568435..7663e574d8 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -1317,11 +1317,28 @@ 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); @@ -1329,6 +1346,9 @@ static struct lo_dirp *lo_dirp(fuse_req_t req, struct= 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; @@ -1364,6 +1384,7 @@ static void lo_opendir(fuse_req_t req, fuse_ino_t ino= , d->offset =3D 0; d->entry =3D NULL; =20 + g_atomic_int_set(&d->refcount, 1); /* paired with lo_releasedir() */ pthread_mutex_lock(&lo->mutex); fh =3D lo_add_dirp_mapping(req, d); pthread_mutex_unlock(&lo->mutex); @@ -1397,7 +1418,7 @@ 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 plu= s) { 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; @@ -1487,6 +1508,8 @@ 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 @@ -1517,22 +1540,25 @@ static void lo_releasedir(fuse_req_t req, fuse_ino_= t ino, struct fuse_file_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 @@ -1743,6 +1769,9 @@ static void lo_fsyncdir(fuse_req_t req, fuse_ino_t in= o, int datasync, } else { res =3D fsync(fd); } + + lo_dirp_put(&d); + fuse_reply_err(req, res =3D=3D -1 ? errno : 0); } =20 --=20 2.23.0