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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 88AA8C32774 for ; Tue, 23 Aug 2022 10:57:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356791AbiHWKy4 (ORCPT ); Tue, 23 Aug 2022 06:54:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38704 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349551AbiHWKrv (ORCPT ); Tue, 23 Aug 2022 06:47:51 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 786B886B73; Tue, 23 Aug 2022 02:11:57 -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 ECCFE60DB4; Tue, 23 Aug 2022 09:11:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2237C433C1; Tue, 23 Aug 2022 09:11:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661245916; bh=kd+I0XmUbXIJ/LwRaRmEi5NAIq3Uh9Kly8zTmhiZkac=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hQoCJyGC+0RvDcoStiFgqTly70mcn7WHvxty1fKYwe6bwnq3uosiyYU1b0L3Zp+vZ pv+uleJTGnYI+27eBI+dvV7qpzvtOZlQToDX5EYeMtiRHjUEoEj9ipPB9+Po9zTVEv yju9cREq/G+eJFfk9N8cLwbhXN9SVKuiDgEbgMrQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Trond Myklebust Subject: [PATCH 4.19 230/287] NFSv4: Fix races in the legacy idmapper upcall Date: Tue, 23 Aug 2022 10:26:39 +0200 Message-Id: <20220823080108.778835691@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080100.268827165@linuxfoundation.org> References: <20220823080100.268827165@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Trond Myklebust commit 51fd2eb52c0ca8275a906eed81878ef50ae94eb0 upstream. nfs_idmap_instantiate() will cause the process that is waiting in request_key_with_auxdata() to wake up and exit. If there is a second process waiting for the idmap->idmap_mutex, then it may wake up and start a new call to request_key_with_auxdata(). If the call to idmap_pipe_downcall() from the first process has not yet finished calling nfs_idmap_complete_pipe_upcall_locked(), then we may end up triggering the WARN_ON_ONCE() in nfs_idmap_prepare_pipe_upcall(). The fix is to ensure that we clear idmap->idmap_upcall_data before calling nfs_idmap_instantiate(). Fixes: e9ab41b620e4 ("NFSv4: Clean up the legacy idmapper upcall") Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman --- fs/nfs/nfs4idmap.c | 46 ++++++++++++++++++++++++---------------------- 1 file changed, 24 insertions(+), 22 deletions(-) --- a/fs/nfs/nfs4idmap.c +++ b/fs/nfs/nfs4idmap.c @@ -547,22 +547,20 @@ nfs_idmap_prepare_pipe_upcall(struct idm return true; } -static void -nfs_idmap_complete_pipe_upcall_locked(struct idmap *idmap, int ret) +static void nfs_idmap_complete_pipe_upcall(struct idmap_legacy_upcalldata *data, + int ret) { - struct key *authkey = idmap->idmap_upcall_data->authkey; - - kfree(idmap->idmap_upcall_data); - idmap->idmap_upcall_data = NULL; - complete_request_key(authkey, ret); - key_put(authkey); + complete_request_key(data->authkey, ret); + key_put(data->authkey); + kfree(data); } -static void -nfs_idmap_abort_pipe_upcall(struct idmap *idmap, int ret) +static void nfs_idmap_abort_pipe_upcall(struct idmap *idmap, + struct idmap_legacy_upcalldata *data, + int ret) { - if (idmap->idmap_upcall_data != NULL) - nfs_idmap_complete_pipe_upcall_locked(idmap, ret); + if (cmpxchg(&idmap->idmap_upcall_data, data, NULL) == data) + nfs_idmap_complete_pipe_upcall(data, ret); } static int nfs_idmap_legacy_upcall(struct key *authkey, void *aux) @@ -599,7 +597,7 @@ static int nfs_idmap_legacy_upcall(struc ret = rpc_queue_upcall(idmap->idmap_pipe, msg); if (ret < 0) - nfs_idmap_abort_pipe_upcall(idmap, ret); + nfs_idmap_abort_pipe_upcall(idmap, data, ret); return ret; out2: @@ -655,6 +653,7 @@ idmap_pipe_downcall(struct file *filp, c struct request_key_auth *rka; struct rpc_inode *rpci = RPC_I(file_inode(filp)); struct idmap *idmap = (struct idmap *)rpci->private; + struct idmap_legacy_upcalldata *data; struct key *authkey; struct idmap_msg im; size_t namelen_in; @@ -664,10 +663,11 @@ idmap_pipe_downcall(struct file *filp, c * will have been woken up and someone else may now have used * idmap_key_cons - so after this point we may no longer touch it. */ - if (idmap->idmap_upcall_data == NULL) + data = xchg(&idmap->idmap_upcall_data, NULL); + if (data == NULL) goto out_noupcall; - authkey = idmap->idmap_upcall_data->authkey; + authkey = data->authkey; rka = get_request_key_auth(authkey); if (mlen != sizeof(im)) { @@ -689,18 +689,17 @@ idmap_pipe_downcall(struct file *filp, c if (namelen_in == 0 || namelen_in == IDMAP_NAMESZ) { ret = -EINVAL; goto out; -} + } - ret = nfs_idmap_read_and_verify_message(&im, - &idmap->idmap_upcall_data->idmap_msg, - rka->target_key, authkey); + ret = nfs_idmap_read_and_verify_message(&im, &data->idmap_msg, + rka->target_key, authkey); if (ret >= 0) { key_set_timeout(rka->target_key, nfs_idmap_cache_timeout); ret = mlen; } out: - nfs_idmap_complete_pipe_upcall_locked(idmap, ret); + nfs_idmap_complete_pipe_upcall(data, ret); out_noupcall: return ret; } @@ -714,7 +713,7 @@ idmap_pipe_destroy_msg(struct rpc_pipe_m struct idmap *idmap = data->idmap; if (msg->errno) - nfs_idmap_abort_pipe_upcall(idmap, msg->errno); + nfs_idmap_abort_pipe_upcall(idmap, data, msg->errno); } static void @@ -722,8 +721,11 @@ idmap_release_pipe(struct inode *inode) { struct rpc_inode *rpci = RPC_I(inode); struct idmap *idmap = (struct idmap *)rpci->private; + struct idmap_legacy_upcalldata *data; - nfs_idmap_abort_pipe_upcall(idmap, -EPIPE); + data = xchg(&idmap->idmap_upcall_data, NULL); + if (data) + nfs_idmap_complete_pipe_upcall(data, -EPIPE); } int nfs_map_name_to_uid(const struct nfs_server *server, const char *name, size_t namelen, kuid_t *uid)