From patchwork Tue Apr 26 08:20:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 566675 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 32B3BC433F5 for ; Tue, 26 Apr 2022 08:35:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345151AbiDZIiE (ORCPT ); Tue, 26 Apr 2022 04:38:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345167AbiDZIgs (ORCPT ); Tue, 26 Apr 2022 04:36:48 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 249E38879A; Tue, 26 Apr 2022 01:29:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B6D02617E7; Tue, 26 Apr 2022 08:29:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B529AC385AC; Tue, 26 Apr 2022 08:29:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650961744; bh=xekvh54C44ahrLQv498FL4hhn2bRb7cr2r2BeQabwWs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nXIrbZUk/QhlbwpMdch2ZENXmCTzbZRF7thT34bZPT1coocoPR9lXwms6qxaDeKmY HHOkK6GlmPojLg+aHow2hff97t4y9lPAMFIzT2E80fzM2syN0cfIWlbczvDrlqM9Ng uCbqXFosxdeutcEPXt02j9puOFv8syjnxlLQK1dE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Howells , Eric Dumazet , Marc Dionne , linux-afs@lists.infradead.org, "David S. Miller" , Sasha Levin Subject: [PATCH 5.4 16/62] rxrpc: Restore removed timer deletion Date: Tue, 26 Apr 2022 10:20:56 +0200 Message-Id: <20220426081737.692804682@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220426081737.209637816@linuxfoundation.org> References: <20220426081737.209637816@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: David Howells [ Upstream commit ee3b0826b4764f6c13ad6db67495c5a1c38e9025 ] A recent patch[1] from Eric Dumazet flipped the order in which the keepalive timer and the keepalive worker were cancelled in order to fix a syzbot reported issue[2]. Unfortunately, this enables the mirror image bug whereby the timer races with rxrpc_exit_net(), restarting the worker after it has been cancelled: CPU 1 CPU 2 =============== ===================== if (rxnet->live) rxnet->live = false; cancel_work_sync(&rxnet->peer_keepalive_work); rxrpc_queue_work(&rxnet->peer_keepalive_work); del_timer_sync(&rxnet->peer_keepalive_timer); Fix this by restoring the removed del_timer_sync() so that we try to remove the timer twice. If the timer runs again, it should see ->live == false and not restart the worker. Fixes: 1946014ca3b1 ("rxrpc: fix a race in rxrpc_exit_net()") Signed-off-by: David Howells cc: Eric Dumazet cc: Marc Dionne cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/20220404183439.3537837-1-eric.dumazet@gmail.com/ [1] Link: https://syzkaller.appspot.com/bug?extid=724378c4bb58f703b09a [2] Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/rxrpc/net_ns.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/rxrpc/net_ns.c b/net/rxrpc/net_ns.c index 9a76b74af37b..91a503871116 100644 --- a/net/rxrpc/net_ns.c +++ b/net/rxrpc/net_ns.c @@ -116,7 +116,9 @@ static __net_exit void rxrpc_exit_net(struct net *net) struct rxrpc_net *rxnet = rxrpc_net(net); rxnet->live = false; + del_timer_sync(&rxnet->peer_keepalive_timer); cancel_work_sync(&rxnet->peer_keepalive_work); + /* Remove the timer again as the worker may have restarted it. */ del_timer_sync(&rxnet->peer_keepalive_timer); rxrpc_destroy_all_calls(rxnet); rxrpc_destroy_all_connections(rxnet);