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 E03B7C00144 for ; Mon, 1 Aug 2022 11:47:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230238AbiHALr0 (ORCPT ); Mon, 1 Aug 2022 07:47:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33800 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229892AbiHALrZ (ORCPT ); Mon, 1 Aug 2022 07:47:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5B64357E3 for ; Mon, 1 Aug 2022 04:47:24 -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 3DA84612C6 for ; Mon, 1 Aug 2022 11:47:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A1F6C433C1; Mon, 1 Aug 2022 11:47:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659354443; bh=LIGL9weSYUePxvV8yw1LKvfBLFSQ2jw7uu6eXTUtDpo=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=fMU2cIclrW+mGEJ+Ty8Vss7RHWzfHQy4jDxttypR9ucvMVdK/dj+jEfe2pVzW4rZF 3gyjpJNQurPIAYy/KTS6jqpjCk+PL6PsYKP5uaiLfT4I22OEMD2tqALhDNsw3Z6qYe LOSJjVCs7l4bAoxiGBU4QIjU9YOAjEEnTSU0XdVcq5zSIvQ3ORDOdN15am7KwjOufb m/iC0x49jbsSLT9l8rYCm6R/uI3QTzbF4uoIEuLt1asZoIp1Pv8caUcX1y6f881Z3R 9kJQCywcivexfxQn9v17QR7kMcJonWdYWZMHGNb4DMte3gqiLP5FnYk5uUidwjZPRv Ky5ICzrAScVNA== Message-ID: Subject: Re: [PATCH] NFSD: fix use-after-free on source server when doing inter-server copy From: Jeff Layton To: Dai Ngo , chuck.lever@oracle.com, olga.kornievskaia@gmail.com Cc: linux-nfs@vger.kernel.org Date: Mon, 01 Aug 2022 07:47:21 -0400 In-Reply-To: <1659298792-5735-1-git-send-email-dai.ngo@oracle.com> References: <1659298792-5735-1-git-send-email-dai.ngo@oracle.com> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.3 (3.44.3-1.fc36) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Sun, 2022-07-31 at 13:19 -0700, Dai Ngo wrote: > Use-after-free occurred when the laundromat tried to free expired > cpntf_state entry on the s2s_cp_stateids list after inter-server > copy completed. The sc_cp_list that the expired copy state was > inserted on was already freed. >=20 > When COPY completes, the Linux client normally sends LOCKU(lock_state x), > FREE_STATEID(lock_state x) and CLOSE(open_state y) to the source server. > The nfs4_put_stid call from nfsd4_free_stateid cleans up the copy state > from the s2s_cp_stateids list before freeing the lock state's stid. >=20 > However, sometimes the CLOSE was sent before the FREE_STATEID request. > When this happens, the nfsd4_close_open_stateid call from nfsd4_close > frees all lock states on its st_locks list without cleaning up the copy > state on the sc_cp_list list. When the time the FREE_STATEID arrives the > server returns BAD_STATEID since the lock state was freed. This causes > the use-after-free error to occur when the laundromat tries to free > the expired cpntf_state. >=20 > This patch adds a call to nfs4_free_cpntf_statelist in > nfsd4_close_open_stateid to clean up the copy state before calling > free_ol_stateid_reaplist to free the lock state's stid on the reaplist. >=20 > Signed-off-by: Dai Ngo > --- > fs/nfsd/nfs4state.c | 3 +++ > 1 file changed, 3 insertions(+) >=20 > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index 9409a0dc1b76..749f51dff5c7 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -6608,6 +6608,7 @@ static void nfsd4_close_open_stateid(struct nfs4_ol= _stateid *s) > struct nfs4_client *clp =3D s->st_stid.sc_client; > bool unhashed; > LIST_HEAD(reaplist); > + struct nfs4_ol_stateid *stp; > =20 > spin_lock(&clp->cl_lock); > unhashed =3D unhash_open_stateid(s, &reaplist); > @@ -6616,6 +6617,8 @@ static void nfsd4_close_open_stateid(struct nfs4_ol= _stateid *s) > if (unhashed) > put_ol_stateid_locked(s, &reaplist); > spin_unlock(&clp->cl_lock); > + list_for_each_entry(stp, &reaplist, st_locks) > + nfs4_free_cpntf_statelist(clp->net, &stp->st_stid); > free_ol_stateid_reaplist(&reaplist); > } else { > spin_unlock(&clp->cl_lock); Nice catch. There are a number of places that call free_ol_stateid_reaplist. Is it really only in nfsd4_close_open_stateid that we need to do this? I wonder if it would be better to do this inside free_ol_stateid_reaplist instead so that all of those callers clean up the copy states as well? --=20 Jeff Layton