From patchwork Tue Apr 5 07:18:45 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: 557202 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 A294CC4708A for ; Tue, 5 Apr 2022 10:46:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244488AbiDEKix (ORCPT ); Tue, 5 Apr 2022 06:38:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40174 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238963AbiDEJdN (ORCPT ); Tue, 5 Apr 2022 05:33:13 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99CD063FD; Tue, 5 Apr 2022 02:21:02 -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 ams.source.kernel.org (Postfix) with ESMTPS id 5170BB81C77; Tue, 5 Apr 2022 09:21:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93A8BC385A3; Tue, 5 Apr 2022 09:20:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649150460; bh=mIYdWx0WBpNnvt8DHmteblO2kXpl0mYYQv47KMUPvpU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bpADlPwX4RpdO+mJsvCpdrmzgoOASS1hX9NIW82kUn2csq3nSPd1JDUi2xRiHV9zv S9FNTtN0jguyxxbtGSDDpXpxI3RSha7qvPZoWSdkhnzcyNxR9T5kCLULC/D7MlaoFK O2pHxE93gWm3KModYejT88yLR8R5ja9JGHzvqVQk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, NeilBrown , Trond Myklebust Subject: [PATCH 5.15 063/913] SUNRPC: avoid race between mod_timer() and del_timer_sync() Date: Tue, 5 Apr 2022 09:18:45 +0200 Message-Id: <20220405070341.712316511@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070339.801210740@linuxfoundation.org> References: <20220405070339.801210740@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: NeilBrown commit 3848e96edf4788f772d83990022fa7023a233d83 upstream. xprt_destory() claims XPRT_LOCKED and then calls del_timer_sync(). Both xprt_unlock_connect() and xprt_release() call ->release_xprt() which drops XPRT_LOCKED and *then* xprt_schedule_autodisconnect() which calls mod_timer(). This may result in mod_timer() being called *after* del_timer_sync(). When this happens, the timer may fire long after the xprt has been freed, and run_timer_softirq() will probably crash. The pairing of ->release_xprt() and xprt_schedule_autodisconnect() is always called under ->transport_lock. So if we take ->transport_lock to call del_timer_sync(), we can be sure that mod_timer() will run first (if it runs at all). Cc: stable@vger.kernel.org Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/xprt.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -2111,7 +2111,14 @@ static void xprt_destroy(struct rpc_xprt */ wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE); + /* + * xprt_schedule_autodisconnect() can run after XPRT_LOCKED + * is cleared. We use ->transport_lock to ensure the mod_timer() + * can only run *before* del_time_sync(), never after. + */ + spin_lock(&xprt->transport_lock); del_timer_sync(&xprt->timer); + spin_unlock(&xprt->transport_lock); /* * Destroy sockets etc from the system workqueue so they can