linux-kernel - [PATCH 3.16 196/305] NFSv4: Don't exit the state manager without clearing NFS4CLNT_MANAGER

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1549201508.157456847@decadent.org.uk>
Date:   Sun, 03 Feb 2019 14:45:08 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Trond Myklebust" <trond.myklebust@...merspace.com>
Subject: [PATCH 3.16 196/305] NFSv4: Don't exit the state manager without
 clearing NFS4CLNT_MANAGER_RUNNING

3.16.63-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <trond.myklebust@...merspace.com>

commit 21a446cf186570168b7281b154b1993968598aca upstream.

If we exit the NFSv4 state manager due to a umount, then we can end up
leaving the NFS4CLNT_MANAGER_RUNNING flag set. If another mount causes
the nfs4_client to be rereferenced before it is destroyed, then we end
up never being able to recover state.

Fixes: 47c2199b6eb5 ("NFSv4.1: Ensure state manager thread dies on last ...")
Signed-off-by: Trond Myklebust <trond.myklebust@...merspace.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/nfs/nfs4state.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -2427,11 +2427,12 @@ static void nfs4_state_manager(struct nf
 		nfs4_clear_state_manager_bit(clp);
 		/* Did we race with an attempt to give us more work? */
 		if (clp->cl_state == 0)
-			break;
+			return;
 		if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
-			break;
+			return;
 	} while (atomic_read(&clp->cl_count) > 1);
-	return;
+	goto out_drain;
+
 out_error:
 	if (strlen(section))
 		section_sep = ": ";
@@ -2439,6 +2440,7 @@ out_error:
 			" with error %d\n", section_sep, section,
 			clp->cl_hostname, -status);
 	ssleep(1);
+out_drain:
 	nfs4_end_drain_session(clp);
 	nfs4_clear_state_manager_bit(clp);
 }