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 2AD54C433F5 for ; Sun, 12 Dec 2021 13:11:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229739AbhLLNLw (ORCPT ); Sun, 12 Dec 2021 08:11:52 -0500 Received: from sin.source.kernel.org ([145.40.73.55]:47050 "EHLO sin.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230515AbhLLNLv (ORCPT ); Sun, 12 Dec 2021 08:11:51 -0500 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 sin.source.kernel.org (Postfix) with ESMTPS id 7ACB0CE09E6 for ; Sun, 12 Dec 2021 13:11:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E142C341C5; Sun, 12 Dec 2021 13:11:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1639314708; bh=Cvz/DObEPfnwRSbgjdy5gO3Ipbu7Xa8oEF5BdVZjqtM=; h=Subject:To:Cc:From:Date:From; b=SM2Vs55GbHYS/RnuIPVkXWeEbLAVeY+riKsvbIxPu0SWYBJONV3/a6WovvrXZZyqS idvSYYIHUcXxQ8eT7bs2R0X+k6qXPALRoAE0ijIgHy2molJ7FFslEwlj0YMLxPKwFw fPqd34WH9FyeeCzztrch8A5crrABo2UEF+NUsO0I= Subject: FAILED: patch "[PATCH] nfsd: fix use-after-free due to delegation race" failed to apply to 4.19-stable tree To: bfields@redhat.com Cc: From: Date: Sun, 12 Dec 2021 14:11:30 +0100 Message-ID: <1639314690415@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 548ec0805c399c65ed66c6641be467f717833ab5 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Mon, 29 Nov 2021 15:08:00 -0500 Subject: [PATCH] nfsd: fix use-after-free due to delegation race 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 diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index bfad94c70b84..1956d377d1a6 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -1207,6 +1207,11 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp) 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) { @@ -1214,7 +1219,7 @@ unhash_delegation_locked(struct nfs4_delegation *dp) 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; @@ -4598,7 +4603,7 @@ static void nfsd4_cb_recall_prepare(struct nfsd4_callback *cb) * 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 = ktime_get_boottime_seconds(); list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru); }