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Commit d3be4d24 authored by David Howells's avatar David Howells
Browse files

rxrpc: Fix potential call vs socket/net destruction race 



rxrpc_call structs don't pin sockets or network namespaces, but may attempt
to access both after their refcount reaches 0 so that they can detach
themselves from the network namespace.  However, there's no guarantee that
the socket still exists at this point (so sock_net(&call->socket->sk) may
be invalid) and the namespace may have gone away if the call isn't pinning
a peer.

Fix this by (a) carrying a net pointer in the rxrpc_call struct and (b)
waiting for all calls to be destroyed when the network namespace goes away.

This was detected by checker:

net/rxrpc/call_object.c:634:57: warning: incorrect type in argument 1 (different address spaces)
net/rxrpc/call_object.c:634:57:    expected struct sock const *sk
net/rxrpc/call_object.c:634:57:    got struct sock [noderef] <asn:4>*<noident>

Fixes: 2baec2c3 ("rxrpc: Support network namespacing")
Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
parent 88f2a825

net/rxrpc/ar-internal.h

+2 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ struct rxrpc_net { 
	u32			epoch;		/* Local epoch for detecting local-end reset */

	struct list_head	calls;		/* List of calls active in this namespace */

	rwlock_t		call_lock;	/* Lock for ->calls */

	atomic_t		nr_calls;	/* Count of allocated calls */



	struct list_head	conn_proc_list;	/* List of conns in this namespace for proc */

	struct list_head	service_conns;	/* Service conns in this namespace */
@@ -528,6 +529,7 @@ struct rxrpc_call { 
	struct rxrpc_connection	*conn;		/* connection carrying call */

	struct rxrpc_peer	*peer;		/* Peer record for remote address */

	struct rxrpc_sock __rcu	*socket;	/* socket responsible */

	struct rxrpc_net	*rxnet;		/* Network namespace to which call belongs */

	struct mutex		user_mutex;	/* User access mutex */

	unsigned long		ack_at;		/* When deferred ACK needs to happen */

	unsigned long		ack_lost_at;	/* When ACK is figured as lost */

net/rxrpc/call_accept.c

+1 −0
Original line number Diff line number Diff line
@@ -138,6 +138,7 @@ static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx, 


	write_unlock(&rx->call_lock);



	rxnet = call->rxnet;

	write_lock(&rxnet->call_lock);

	list_add_tail(&call->link, &rxnet->calls);

	write_unlock(&rxnet->call_lock);

net/rxrpc/call_object.c

+13 −3
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ struct rxrpc_call *rxrpc_alloc_call(struct rxrpc_sock *rx, gfp_t gfp, 
				    unsigned int debug_id)

{

	struct rxrpc_call *call;

	struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));



	call = kmem_cache_zalloc(rxrpc_call_jar, gfp);

	if (!call)
@@ -153,6 +154,9 @@ struct rxrpc_call *rxrpc_alloc_call(struct rxrpc_sock *rx, gfp_t gfp, 


	call->cong_cwnd = 2;

	call->cong_ssthresh = RXRPC_RXTX_BUFF_SIZE - 1;



	call->rxnet = rxnet;

	atomic_inc(&rxnet->nr_calls);

	return call;



nomem_2:
@@ -222,7 +226,7 @@ struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx, 
	__acquires(&call->user_mutex)

{

	struct rxrpc_call *call, *xcall;

	struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));

	struct rxrpc_net *rxnet;

	struct rb_node *parent, **pp;

	const void *here = __builtin_return_address(0);

	int ret;
@@ -272,6 +276,7 @@ struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx, 


	write_unlock(&rx->call_lock);



	rxnet = call->rxnet;

	write_lock(&rxnet->call_lock);

	list_add_tail(&call->link, &rxnet->calls);

	write_unlock(&rxnet->call_lock);
@@ -617,7 +622,7 @@ void rxrpc_release_calls_on_socket(struct rxrpc_sock *rx) 
 */

void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op)

{

	struct rxrpc_net *rxnet;

	struct rxrpc_net *rxnet = call->rxnet;

	const void *here = __builtin_return_address(0);

	int n;
@@ -631,7 +636,6 @@ void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op) 
		ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);



		if (!list_empty(&call->link)) {

			rxnet = rxrpc_net(sock_net(&call->socket->sk));

			write_lock(&rxnet->call_lock);

			list_del_init(&call->link);

			write_unlock(&rxnet->call_lock);
@@ -647,11 +651,14 @@ void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op) 
static void rxrpc_rcu_destroy_call(struct rcu_head *rcu)

{

	struct rxrpc_call *call = container_of(rcu, struct rxrpc_call, rcu);

	struct rxrpc_net *rxnet = call->rxnet;



	rxrpc_put_peer(call->peer);

	kfree(call->rxtx_buffer);

	kfree(call->rxtx_annotations);

	kmem_cache_free(rxrpc_call_jar, call);

	if (atomic_dec_and_test(&rxnet->nr_calls))

		wake_up_atomic_t(&rxnet->nr_calls);

}



/*
@@ -716,4 +723,7 @@ void rxrpc_destroy_all_calls(struct rxrpc_net *rxnet) 
	}



	write_unlock(&rxnet->call_lock);



	atomic_dec(&rxnet->nr_calls);

	wait_on_atomic_t(&rxnet->nr_calls, atomic_t_wait, TASK_UNINTERRUPTIBLE);

}

net/rxrpc/net_ns.c

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ static __net_init int rxrpc_init_net(struct net *net) 


	INIT_LIST_HEAD(&rxnet->calls);

	rwlock_init(&rxnet->call_lock);

	atomic_set(&rxnet->nr_calls, 1);



	INIT_LIST_HEAD(&rxnet->conn_proc_list);

	INIT_LIST_HEAD(&rxnet->service_conns);