kernel_optimize_test/net/rxrpc/net_ns.c
David Howells 60592f16a4 rxrpc: Restore removed timer deletion
[ Upstream commit ee3b0826b4764f6c13ad6db67495c5a1c38e9025 ]

A recent patch[1] from Eric Dumazet flipped the order in which the
keepalive timer and the keepalive worker were cancelled in order to fix a
syzbot reported issue[2].  Unfortunately, this enables the mirror image bug
whereby the timer races with rxrpc_exit_net(), restarting the worker after
it has been cancelled:

	CPU 1		CPU 2
	===============	=====================
			if (rxnet->live)
			<INTERRUPT>
	rxnet->live = false;
 	cancel_work_sync(&rxnet->peer_keepalive_work);
			rxrpc_queue_work(&rxnet->peer_keepalive_work);
	del_timer_sync(&rxnet->peer_keepalive_timer);

Fix this by restoring the removed del_timer_sync() so that we try to remove
the timer twice.  If the timer runs again, it should see ->live == false
and not restart the worker.

Fixes: 1946014ca3b1 ("rxrpc: fix a race in rxrpc_exit_net()")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Eric Dumazet <edumazet@google.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: https://lore.kernel.org/r/20220404183439.3537837-1-eric.dumazet@gmail.com/ [1]
Link: https://syzkaller.appspot.com/bug?extid=724378c4bb58f703b09a [2]
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-27 13:53:49 +02:00

133 lines
3.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* rxrpc network namespace handling.
*
* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/proc_fs.h>
#include "ar-internal.h"
unsigned int rxrpc_net_id;
static void rxrpc_client_conn_reap_timeout(struct timer_list *timer)
{
struct rxrpc_net *rxnet =
container_of(timer, struct rxrpc_net, client_conn_reap_timer);
if (rxnet->live)
rxrpc_queue_work(&rxnet->client_conn_reaper);
}
static void rxrpc_service_conn_reap_timeout(struct timer_list *timer)
{
struct rxrpc_net *rxnet =
container_of(timer, struct rxrpc_net, service_conn_reap_timer);
if (rxnet->live)
rxrpc_queue_work(&rxnet->service_conn_reaper);
}
static void rxrpc_peer_keepalive_timeout(struct timer_list *timer)
{
struct rxrpc_net *rxnet =
container_of(timer, struct rxrpc_net, peer_keepalive_timer);
if (rxnet->live)
rxrpc_queue_work(&rxnet->peer_keepalive_work);
}
/*
* Initialise a per-network namespace record.
*/
static __net_init int rxrpc_init_net(struct net *net)
{
struct rxrpc_net *rxnet = rxrpc_net(net);
int ret, i;
rxnet->live = true;
get_random_bytes(&rxnet->epoch, sizeof(rxnet->epoch));
rxnet->epoch |= RXRPC_RANDOM_EPOCH;
INIT_LIST_HEAD(&rxnet->calls);
rwlock_init(&rxnet->call_lock);
atomic_set(&rxnet->nr_calls, 1);
atomic_set(&rxnet->nr_conns, 1);
INIT_LIST_HEAD(&rxnet->conn_proc_list);
INIT_LIST_HEAD(&rxnet->service_conns);
rwlock_init(&rxnet->conn_lock);
INIT_WORK(&rxnet->service_conn_reaper,
rxrpc_service_connection_reaper);
timer_setup(&rxnet->service_conn_reap_timer,
rxrpc_service_conn_reap_timeout, 0);
atomic_set(&rxnet->nr_client_conns, 0);
rxnet->kill_all_client_conns = false;
spin_lock_init(&rxnet->client_conn_cache_lock);
spin_lock_init(&rxnet->client_conn_discard_lock);
INIT_LIST_HEAD(&rxnet->idle_client_conns);
INIT_WORK(&rxnet->client_conn_reaper,
rxrpc_discard_expired_client_conns);
timer_setup(&rxnet->client_conn_reap_timer,
rxrpc_client_conn_reap_timeout, 0);
INIT_LIST_HEAD(&rxnet->local_endpoints);
mutex_init(&rxnet->local_mutex);
hash_init(rxnet->peer_hash);
spin_lock_init(&rxnet->peer_hash_lock);
for (i = 0; i < ARRAY_SIZE(rxnet->peer_keepalive); i++)
INIT_LIST_HEAD(&rxnet->peer_keepalive[i]);
INIT_LIST_HEAD(&rxnet->peer_keepalive_new);
timer_setup(&rxnet->peer_keepalive_timer,
rxrpc_peer_keepalive_timeout, 0);
INIT_WORK(&rxnet->peer_keepalive_work, rxrpc_peer_keepalive_worker);
rxnet->peer_keepalive_base = ktime_get_seconds();
ret = -ENOMEM;
rxnet->proc_net = proc_net_mkdir(net, "rxrpc", net->proc_net);
if (!rxnet->proc_net)
goto err_proc;
proc_create_net("calls", 0444, rxnet->proc_net, &rxrpc_call_seq_ops,
sizeof(struct seq_net_private));
proc_create_net("conns", 0444, rxnet->proc_net,
&rxrpc_connection_seq_ops,
sizeof(struct seq_net_private));
proc_create_net("peers", 0444, rxnet->proc_net,
&rxrpc_peer_seq_ops,
sizeof(struct seq_net_private));
return 0;
err_proc:
rxnet->live = false;
return ret;
}
/*
* Clean up a per-network namespace record.
*/
static __net_exit void rxrpc_exit_net(struct net *net)
{
struct rxrpc_net *rxnet = rxrpc_net(net);
rxnet->live = false;
del_timer_sync(&rxnet->peer_keepalive_timer);
cancel_work_sync(&rxnet->peer_keepalive_work);
/* Remove the timer again as the worker may have restarted it. */
del_timer_sync(&rxnet->peer_keepalive_timer);
rxrpc_destroy_all_calls(rxnet);
rxrpc_destroy_all_connections(rxnet);
rxrpc_destroy_all_peers(rxnet);
rxrpc_destroy_all_locals(rxnet);
proc_remove(rxnet->proc_net);
}
struct pernet_operations rxrpc_net_ops = {
.init = rxrpc_init_net,
.exit = rxrpc_exit_net,
.id = &rxrpc_net_id,
.size = sizeof(struct rxrpc_net),
};