From nobody Fri Oct 3 11:29:48 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1579805794; cv=none; d=zohomail.com; s=zohoarc; b=cCegeMFcMyXDv9Cro2CmbkdGc/+HmIREcaDjM2ApilrtNoYmDdSMDJNAd9w2PiBRPcE+jByaOLjl95byqjJfp9tFRSMTpvvrzpWW1J0k3xtOMxfezg/0eD42+u1x7BDRBfEmTqxDEaoDTGs60BjkaVp/CVUd5B4weD218/uSaOI= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1579805794; h=Content-Type:Content-Transfer-Encoding:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=3ReKNj1rFDFIIQee82NxUM9rjpuTICrYfS2n3sBKG9Y=; b=ntYsGzPxwkKc+LqjFwlvkxmZXj9kh79BWXE+Ppn1MKJKmvfKhWozyrl6K1W6sxOkva3PXY4+aF4uEi5RFgegklGD8M4cYvyov0Woj8VVtfTkX1bVzoXhvzb9WoKtjbOXqFtXkqrbX/uUM2PSWp1KLZc37LYPNCf2nejBFkzbhg4= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1579805794188773.2508404143038; Thu, 23 Jan 2020 10:56:34 -0800 (PST) Received: from localhost ([::1]:35178 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iuhea-0005pS-IK for importer@patchew.org; Thu, 23 Jan 2020 13:56:32 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:42462) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iufep-00061W-Hz for qemu-devel@nongnu.org; Thu, 23 Jan 2020 11:48:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iufeo-0008Lu-7m for qemu-devel@nongnu.org; Thu, 23 Jan 2020 11:48:39 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:39153 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 1iufen-0008KB-Rl for qemu-devel@nongnu.org; Thu, 23 Jan 2020 11:48:38 -0500 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-96-CyXn6GHAMoyiKLwBxak2Ug-1; Thu, 23 Jan 2020 11:48:35 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EDA288024D8 for ; Thu, 23 Jan 2020 16:48:34 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-116-110.ams2.redhat.com [10.36.116.110]) by smtp.corp.redhat.com (Postfix) with ESMTP id 466E119C69; Thu, 23 Jan 2020 16:48:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579798117; 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=3ReKNj1rFDFIIQee82NxUM9rjpuTICrYfS2n3sBKG9Y=; b=LVjz1BPIElf3N7BO/Gh2MAfyGdv3Tx0hOWRjAC4aKLYDVvdssjZox6UxLHtaN5XSnM/pGz QdywsKUp0DnwOEbFMvagmxxIBbw1hKE7Q8ZYEVa5CTjsIDpqN2ly8oftR0M0E/oBlVCeqM t4GNrAjcKrX+dUhMBJwWKD68t77G56k= From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, stefanha@redhat.com Subject: [PULL 089/108] virtiofsd: prevent races with lo_dirp_put() Date: Thu, 23 Jan 2020 16:46:11 +0000 Message-Id: <20200123164630.91498-90-dgilbert@redhat.com> In-Reply-To: <20200123164630.91498-1-dgilbert@redhat.com> References: <20200123164630.91498-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: CyXn6GHAMoyiKLwBxak2Ug-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] 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+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: pass (identity @redhat.com) Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Philippe Mathieu-Daud=C3=A9 Signed-off-by: Dr. David Alan Gilbert --- 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 690edbc4c5..2d703b57e5 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -1284,11 +1284,28 @@ 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); @@ -1296,6 +1313,9 @@ 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; @@ -1331,6 +1351,7 @@ 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); @@ -1364,7 +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 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; @@ -1454,6 +1475,8 @@ 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 @@ -1484,22 +1507,25 @@ 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 @@ -1710,6 +1736,9 @@ 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 2.24.1