Commit 04d36d74 authored by David Howells's avatar David Howells
Browse files

rxrpc: Fix missing active use pinning of rxrpc_local object 



The introduction of a split between the reference count on rxrpc_local
objects and the usage count didn't quite go far enough.  A number of kernel
work items need to make use of the socket to perform transmission.  These
also need to get an active count on the local object to prevent the socket
from being closed.

Fix this by getting the active count in those places.

Also split out the raw active count get/put functions as these places tend
to hold refs on the rxrpc_local object already, so getting and putting an
extra object ref is just a waste of time.

The problem can lead to symptoms like:

    BUG: kernel NULL pointer dereference, address: 0000000000000018
    ..
    CPU: 2 PID: 818 Comm: kworker/u9:0 Not tainted 5.5.0-fscache+ #51
    ...
    RIP: 0010:selinux_socket_sendmsg+0x5/0x13
    ...
    Call Trace:
     security_socket_sendmsg+0x2c/0x3e
     sock_sendmsg+0x1a/0x46
     rxrpc_send_keepalive+0x131/0x1ae
     rxrpc_peer_keepalive_worker+0x219/0x34b
     process_one_work+0x18e/0x271
     worker_thread+0x1a3/0x247
     kthread+0xe6/0xeb
     ret_from_fork+0x1f/0x30

Fixes: 730c5fd4 ("rxrpc: Fix local endpoint refcounting")
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent f71dbf2f

net/rxrpc/af_rxrpc.c

+2 −0
Original line number Diff line number Diff line
@@ -194,6 +194,7 @@ static int rxrpc_bind(struct socket *sock, struct sockaddr *saddr, int len) 
service_in_use:

	write_unlock(&local->services_lock);

	rxrpc_unuse_local(local);

	rxrpc_put_local(local);

	ret = -EADDRINUSE;

error_unlock:

	release_sock(&rx->sk);
@@ -899,6 +900,7 @@ static int rxrpc_release_sock(struct sock *sk) 
	rxrpc_purge_queue(&sk->sk_receive_queue);



	rxrpc_unuse_local(rx->local);

	rxrpc_put_local(rx->local);

	rx->local = NULL;

	key_put(rx->key);

	rx->key = NULL;

net/rxrpc/ar-internal.h

+10 −0
Original line number Diff line number Diff line
@@ -1021,6 +1021,16 @@ void rxrpc_unuse_local(struct rxrpc_local *); 
void rxrpc_queue_local(struct rxrpc_local *);

void rxrpc_destroy_all_locals(struct rxrpc_net *);



static inline bool __rxrpc_unuse_local(struct rxrpc_local *local)

{

	return atomic_dec_return(&local->active_users) == 0;

}



static inline bool __rxrpc_use_local(struct rxrpc_local *local)

{

	return atomic_fetch_add_unless(&local->active_users, 1, 0) != 0;

}



/*

 * misc.c

 */

net/rxrpc/conn_event.c

+20 −10
Original line number Diff line number Diff line
@@ -438,16 +438,12 @@ again: 
/*

 * connection-level event processor

 */

void rxrpc_process_connection(struct work_struct *work)

static void rxrpc_do_process_connection(struct rxrpc_connection *conn)

{

	struct rxrpc_connection *conn =

		container_of(work, struct rxrpc_connection, processor);

	struct sk_buff *skb;

	u32 abort_code = RX_PROTOCOL_ERROR;

	int ret;



	rxrpc_see_connection(conn);



	if (test_and_clear_bit(RXRPC_CONN_EV_CHALLENGE, &conn->events))

		rxrpc_secure_connection(conn);
@@ -475,18 +471,32 @@ void rxrpc_process_connection(struct work_struct *work) 
		}

	}



out:

	rxrpc_put_connection(conn);

	_leave("");

	return;



requeue_and_leave:

	skb_queue_head(&conn->rx_queue, skb);

	goto out;

	return;



protocol_error:

	if (rxrpc_abort_connection(conn, ret, abort_code) < 0)

		goto requeue_and_leave;

	rxrpc_free_skb(skb, rxrpc_skb_freed);

	goto out;

	return;

}



void rxrpc_process_connection(struct work_struct *work)

{

	struct rxrpc_connection *conn =

		container_of(work, struct rxrpc_connection, processor);



	rxrpc_see_connection(conn);



	if (__rxrpc_use_local(conn->params.local)) {

		rxrpc_do_process_connection(conn);

		rxrpc_unuse_local(conn->params.local);

	}



	rxrpc_put_connection(conn);

	_leave("");

	return;

}

net/rxrpc/local_object.c

+7 −11
Original line number Diff line number Diff line
@@ -383,14 +383,11 @@ void rxrpc_put_local(struct rxrpc_local *local) 
 */

struct rxrpc_local *rxrpc_use_local(struct rxrpc_local *local)

{

	unsigned int au;



	local = rxrpc_get_local_maybe(local);

	if (!local)

		return NULL;



	au = atomic_fetch_add_unless(&local->active_users, 1, 0);

	if (au == 0) {

	if (!__rxrpc_use_local(local)) {

		rxrpc_put_local(local);

		return NULL;

	}
@@ -404,14 +401,11 @@ struct rxrpc_local *rxrpc_use_local(struct rxrpc_local *local) 
 */

void rxrpc_unuse_local(struct rxrpc_local *local)

{

	unsigned int au;



	if (local) {

		au = atomic_dec_return(&local->active_users);

		if (au == 0)

		if (__rxrpc_unuse_local(local)) {

			rxrpc_get_local(local);

			rxrpc_queue_local(local);

		else

			rxrpc_put_local(local);

		}

	}

}
@@ -468,7 +462,7 @@ static void rxrpc_local_processor(struct work_struct *work) 


	do {

		again = false;

		if (atomic_read(&local->active_users) == 0) {

		if (!__rxrpc_use_local(local)) {

			rxrpc_local_destroyer(local);

			break;

		}
@@ -482,6 +476,8 @@ static void rxrpc_local_processor(struct work_struct *work) 
			rxrpc_process_local_events(local);

			again = true;

		}



		__rxrpc_unuse_local(local);

	} while (again);



	rxrpc_put_local(local);

net/rxrpc/peer_event.c

+23 −19
Original line number Diff line number Diff line
@@ -364,6 +364,7 @@ static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet, 
		if (!rxrpc_get_peer_maybe(peer))

			continue;



		if (__rxrpc_use_local(peer->local)) {

			spin_unlock_bh(&rxnet->peer_hash_lock);



			keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME;
@@ -377,14 +378,17 @@ static void rxrpc_peer_keepalive_dispatch(struct rxrpc_net *rxnet, 
				slot = RXRPC_KEEPALIVE_TIME;

			}



		/* A transmission to this peer occurred since last we examined

		 * it so put it into the appropriate future bucket.

			/* A transmission to this peer occurred since last we

			 * examined it so put it into the appropriate future

			 * bucket.

			 */

			slot += cursor;

			slot &= mask;

			spin_lock_bh(&rxnet->peer_hash_lock);

			list_add_tail(&peer->keepalive_link,

				      &rxnet->peer_keepalive[slot & mask]);

			rxrpc_unuse_local(peer->local);

		}

		rxrpc_put_peer_locked(peer);

	}

CRA Git | Maintained and supported by SUSTech CRA and CCSE