Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932114AbdIRJux (ORCPT ); Mon, 18 Sep 2017 05:50:53 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:55126 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753836AbdIRJM1 (ORCPT ); Mon, 18 Sep 2017 05:12:27 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Bob Peterson , Herbert Xu , "David S. Miller" Subject: [PATCH 4.12 10/52] tipc: Fix tipc_sk_reinit handling of -EAGAIN Date: Mon, 18 Sep 2017 11:11:04 +0200 Message-Id: <20170918091018.114176200@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170918091016.620101134@linuxfoundation.org> References: <20170918091016.620101134@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1924 Lines: 58 4.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bob Peterson [ Upstream commit 6c7e983b220f89e03286dc70a41c7ef3a8b409df ] In 9dbbfb0ab6680c6a85609041011484e6658e7d3c function tipc_sk_reinit had additional logic added to loop in the event that function rhashtable_walk_next() returned -EAGAIN. No worries. However, if rhashtable_walk_start returns -EAGAIN, it does "continue", and therefore skips the call to rhashtable_walk_stop(). That has the effect of calling rcu_read_lock() without its paired call to rcu_read_unlock(). Since rcu_read_lock() may be nested, the problem may not be apparent for a while, especially since resize events may be rare. But the comments to rhashtable_walk_start() state: * ...Note that we take the RCU lock in all * cases including when we return an error. So you must always call * rhashtable_walk_stop to clean up. This patch replaces the continue with a goto and label to ensure a matching call to rhashtable_walk_stop(). Signed-off-by: Bob Peterson Acked-by: Herbert Xu Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/tipc/socket.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -2255,8 +2255,8 @@ void tipc_sk_reinit(struct net *net) do { tsk = ERR_PTR(rhashtable_walk_start(&iter)); - if (tsk) - continue; + if (IS_ERR(tsk)) + goto walk_stop; while ((tsk = rhashtable_walk_next(&iter)) && !IS_ERR(tsk)) { spin_lock_bh(&tsk->sk.sk_lock.slock); @@ -2265,7 +2265,7 @@ void tipc_sk_reinit(struct net *net) msg_set_orignode(msg, tn->own_addr); spin_unlock_bh(&tsk->sk.sk_lock.slock); } - +walk_stop: rhashtable_walk_stop(&iter); } while (tsk == ERR_PTR(-EAGAIN)); }