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=-7.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 E4D8FC43441 for ; Thu, 29 Nov 2018 14:16:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ACDCF2145D for ; Thu, 29 Nov 2018 14:16:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="V/rMp+nt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ACDCF2145D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730046AbeK3BWB (ORCPT ); Thu, 29 Nov 2018 20:22:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:43562 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728865AbeK3BWB (ORCPT ); Thu, 29 Nov 2018 20:22:01 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7760D21104; Thu, 29 Nov 2018 14:16:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543500990; bh=i0SaZa/jQKc7kNXfRbDyk3FMOraS5fUUikqhqDo5sCk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V/rMp+nt98KFFB/ttoj7RHvL2ayfA6of2HSEpjxK5SzIsAxxGFd5CjL128Cur2Aum rGgRkz7eD5owPYOOLWWDwHNLGJfDKxgMXqy9teqeR1lUIpJKGykO6yxv9QvUvevdI9 Oc3ukrA6QH7LkjMGnqUYzWFzB9c8Zu/V9bIeenfw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dmitry Vyukov , Rainer Weikusat , Al Viro , Cong Wang , "David S. Miller" , Petr Vorel Subject: [PATCH 3.18 82/83] af_unix: move unix_mknod() out of bindlock Date: Thu, 29 Nov 2018 15:12:40 +0100 Message-Id: <20181129140142.732788522@linuxfoundation.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181129140138.002176596@linuxfoundation.org> References: <20181129140138.002176596@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: WANG Cong commit 0fb44559ffd67de8517098b81f675fa0210f13f0 upstream. Dmitry reported a deadlock scenario: unix_bind() path: u->bindlock ==> sb_writer do_splice() path: sb_writer ==> pipe->mutex ==> u->bindlock In the unix_bind() code path, unix_mknod() does not have to be done with u->bindlock held, since it is a pure fs operation, so we can just move unix_mknod() out. Reported-by: Dmitry Vyukov Tested-by: Dmitry Vyukov Cc: Rainer Weikusat Cc: Al Viro Signed-off-by: Cong Wang Signed-off-by: David S. Miller Cc: Petr Vorel Signed-off-by: Greg Kroah-Hartman --- net/unix/af_unix.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -980,6 +980,7 @@ static int unix_bind(struct socket *sock unsigned int hash; struct unix_address *addr; struct hlist_head *list; + struct path path = { NULL, NULL }; err = -EINVAL; if (sunaddr->sun_family != AF_UNIX) @@ -995,9 +996,20 @@ static int unix_bind(struct socket *sock goto out; addr_len = err; + if (sun_path[0]) { + umode_t mode = S_IFSOCK | + (SOCK_INODE(sock)->i_mode & ~current_umask()); + err = unix_mknod(sun_path, mode, &path); + if (err) { + if (err == -EEXIST) + err = -EADDRINUSE; + goto out; + } + } + err = mutex_lock_interruptible(&u->readlock); if (err) - goto out; + goto out_put; err = -EINVAL; if (u->addr) @@ -1014,16 +1026,6 @@ static int unix_bind(struct socket *sock atomic_set(&addr->refcnt, 1); if (sun_path[0]) { - struct path path; - umode_t mode = S_IFSOCK | - (SOCK_INODE(sock)->i_mode & ~current_umask()); - err = unix_mknod(sun_path, mode, &path); - if (err) { - if (err == -EEXIST) - err = -EADDRINUSE; - unix_release_addr(addr); - goto out_up; - } addr->hash = UNIX_HASH_SIZE; hash = d_backing_inode(path.dentry)->i_ino & (UNIX_HASH_SIZE-1); spin_lock(&unix_table_lock); @@ -1050,6 +1052,9 @@ out_unlock: spin_unlock(&unix_table_lock); out_up: mutex_unlock(&u->readlock); +out_put: + if (err) + path_put(&path); out: return err; }