From patchwork Mon Dec 20 14:34:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 526564 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 DB790C433EF for ; Mon, 20 Dec 2021 14:37:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234099AbhLTOha (ORCPT ); Mon, 20 Dec 2021 09:37:30 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234001AbhLTOhN (ORCPT ); Mon, 20 Dec 2021 09:37:13 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 161F3C061748; Mon, 20 Dec 2021 06:37:13 -0800 (PST) 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 CB16DB80EDF; Mon, 20 Dec 2021 14:37:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 238E5C36AE7; Mon, 20 Dec 2021 14:37:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1640011030; bh=+VbiNoV3uC4e2nm4ERyklkSCq0nqBCoaF+uqfzl/0aY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VQfyt0lwNSBgtS1LqOduRRe8YqS4TVGZKv+QogVZyWw2uLYQ1bT7kCYEJOmwZCWZ7 6KQEkp8ff9d6OSiYfBmjoMJkIJVxduUXHMYfF/O+l+9O+s3sDBfQsdCdi7Y548k9zd NBjqzSja3oP9MOdVJMYbj6wPywbkhgi3iK147WsY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "J. Bruce Fields" , Salvatore Bonaccorso Subject: [PATCH 4.9 11/31] nfsd: fix use-after-free due to delegation race Date: Mon, 20 Dec 2021 15:34:11 +0100 Message-Id: <20211220143020.348679826@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211220143019.974513085@linuxfoundation.org> References: <20211220143019.974513085@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: J. Bruce Fields commit 548ec0805c399c65ed66c6641be467f717833ab5 upstream. A delegation break could arrive as soon as we've called vfs_setlease. A delegation break runs a callback which immediately (in nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we then exit nfs4_set_delegation without hashing the delegation, it will be freed as soon as the callback is done with it, without ever being removed from del_recall_lru. Symptoms show up later as use-after-free or list corruption warnings, usually in the laundromat thread. I suspect aba2072f4523 "nfsd: grant read delegations to clients holding writes" made this bug easier to hit, but I looked as far back as v3.0 and it looks to me it already had the same problem. So I'm not sure where the bug was introduced; it may have been there from the beginning. Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields [Salvatore Bonaccorso: Backport for context changes to versions which do not have 20b7d86f29d3 ("nfsd: use boottime for lease expiry calculation")] Signed-off-by: Salvatore Bonaccorso Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfs4state.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -955,6 +955,11 @@ hash_delegation_locked(struct nfs4_deleg return 0; } +static bool delegation_hashed(struct nfs4_delegation *dp) +{ + return !(list_empty(&dp->dl_perfile)); +} + static bool unhash_delegation_locked(struct nfs4_delegation *dp) { @@ -962,7 +967,7 @@ unhash_delegation_locked(struct nfs4_del lockdep_assert_held(&state_lock); - if (list_empty(&dp->dl_perfile)) + if (!delegation_hashed(dp)) return false; dp->dl_stid.sc_type = NFS4_CLOSED_DELEG_STID; @@ -3882,7 +3887,7 @@ static void nfsd4_cb_recall_prepare(stru * queued for a lease break. Don't queue it again. */ spin_lock(&state_lock); - if (dp->dl_time == 0) { + if (delegation_hashed(dp) && dp->dl_time == 0) { dp->dl_time = get_seconds(); list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru); }