From 7ef43ebaa538e0cc9063cbf84593a05091bcace2 Mon Sep 17 00:00:00 2001 From: Allan Stephens Date: Mon, 12 May 2008 15:42:28 -0700 Subject: [PATCH] tipc: Fix race condition when creating socket or native port This patch eliminates the (very remote) chance of a crash resulting from a partially initialized socket or native port unexpectedly receiving a message. Now, during the creation of a socket or native port, the underlying generic port's lock is not released until all initialization required to handle incoming messages has been done. Signed-off-by: Allan Stephens Signed-off-by: David S. Miller --- include/net/tipc/tipc_port.h | 3 ++- net/tipc/port.c | 20 ++++++++++++-------- net/tipc/ref.c | 12 ++++++++---- net/tipc/socket.c | 5 ++++- net/tipc/subscr.c | 1 + 5 files changed, 27 insertions(+), 14 deletions(-) diff --git a/include/net/tipc/tipc_port.h b/include/net/tipc/tipc_port.h index 11105bcc445..9923e41a821 100644 --- a/include/net/tipc/tipc_port.h +++ b/include/net/tipc/tipc_port.h @@ -84,7 +84,8 @@ struct tipc_port { u32 tipc_createport_raw(void *usr_handle, u32 (*dispatcher)(struct tipc_port *, struct sk_buff *), void (*wakeup)(struct tipc_port *), - const u32 importance); + const u32 importance, + struct tipc_port **tp_ptr); int tipc_reject_msg(struct sk_buff *buf, u32 err); diff --git a/net/tipc/port.c b/net/tipc/port.c index 2f5806410c6..757de38fe6a 100644 --- a/net/tipc/port.c +++ b/net/tipc/port.c @@ -211,15 +211,18 @@ exit: } /** - * tipc_createport_raw - create a native TIPC port + * tipc_createport_raw - create a generic TIPC port * - * Returns local port reference + * Returns port reference, or 0 if unable to create it + * + * Note: The newly created port is returned in the locked state. */ u32 tipc_createport_raw(void *usr_handle, u32 (*dispatcher)(struct tipc_port *, struct sk_buff *), void (*wakeup)(struct tipc_port *), - const u32 importance) + const u32 importance, + struct tipc_port **tp_ptr) { struct port *p_ptr; struct tipc_msg *msg; @@ -237,7 +240,6 @@ u32 tipc_createport_raw(void *usr_handle, return 0; } - tipc_port_lock(ref); p_ptr->publ.usr_handle = usr_handle; p_ptr->publ.max_pkt = MAX_PKT_DEFAULT; p_ptr->publ.ref = ref; @@ -262,7 +264,7 @@ u32 tipc_createport_raw(void *usr_handle, INIT_LIST_HEAD(&p_ptr->port_list); list_add_tail(&p_ptr->port_list, &ports); spin_unlock_bh(&tipc_port_list_lock); - tipc_port_unlock(p_ptr); + *tp_ptr = &p_ptr->publ; return ref; } @@ -1053,6 +1055,7 @@ int tipc_createport(u32 user_ref, { struct user_port *up_ptr; struct port *p_ptr; + struct tipc_port *tp_ptr; u32 ref; up_ptr = kmalloc(sizeof(*up_ptr), GFP_ATOMIC); @@ -1060,12 +1063,13 @@ int tipc_createport(u32 user_ref, warn("Port creation failed, no memory\n"); return -ENOMEM; } - ref = tipc_createport_raw(NULL, port_dispatcher, port_wakeup, importance); - p_ptr = tipc_port_lock(ref); - if (!p_ptr) { + ref = tipc_createport_raw(NULL, port_dispatcher, port_wakeup, + importance, &tp_ptr); + if (ref == 0) { kfree(up_ptr); return -ENOMEM; } + p_ptr = (struct port *)tp_ptr; p_ptr->user_port = up_ptr; up_ptr->user_ref = user_ref; diff --git a/net/tipc/ref.c b/net/tipc/ref.c index 89cbab24d08..a101de86824 100644 --- a/net/tipc/ref.c +++ b/net/tipc/ref.c @@ -142,9 +142,13 @@ void tipc_ref_table_stop(void) /** * tipc_ref_acquire - create reference to an object * - * Return a unique reference value which can be translated back to the pointer - * 'object' at a later time. Also, pass back a pointer to the lock protecting - * the object, but without locking it. + * Register an object pointer in reference table and lock the object. + * Returns a unique reference value that is used from then on to retrieve the + * object pointer, or to determine that the object has been deregistered. + * + * Note: The object is returned in the locked state so that the caller can + * register a partially initialized object, without running the risk that + * the object will be accessed before initialization is complete. */ u32 tipc_ref_acquire(void *object, spinlock_t **lock) @@ -178,13 +182,13 @@ u32 tipc_ref_acquire(void *object, spinlock_t **lock) ref = (next_plus_upper & ~index_mask) + index; entry->ref = ref; entry->object = object; - spin_unlock_bh(&entry->lock); *lock = &entry->lock; } else if (tipc_ref_table.init_point < tipc_ref_table.capacity) { index = tipc_ref_table.init_point++; entry = &(tipc_ref_table.entries[index]); spin_lock_init(&entry->lock); + spin_lock_bh(&entry->lock); ref = tipc_ref_table.start_mask + index; entry->ref = ref; entry->object = object; diff --git a/net/tipc/socket.c b/net/tipc/socket.c index 230f9ca2ad6..38f48795b40 100644 --- a/net/tipc/socket.c +++ b/net/tipc/socket.c @@ -188,6 +188,7 @@ static int tipc_create(struct net *net, struct socket *sock, int protocol) const struct proto_ops *ops; socket_state state; struct sock *sk; + struct tipc_port *tp_ptr; u32 portref; /* Validate arguments */ @@ -225,7 +226,7 @@ static int tipc_create(struct net *net, struct socket *sock, int protocol) /* Allocate TIPC port for socket to use */ portref = tipc_createport_raw(sk, &dispatch, &wakeupdispatch, - TIPC_LOW_IMPORTANCE); + TIPC_LOW_IMPORTANCE, &tp_ptr); if (unlikely(portref == 0)) { sk_free(sk); return -ENOMEM; @@ -241,6 +242,8 @@ static int tipc_create(struct net *net, struct socket *sock, int protocol) sk->sk_backlog_rcv = backlog_rcv; tipc_sk(sk)->p = tipc_get_port(portref); + spin_unlock_bh(tp_ptr->lock); + if (sock->state == SS_READY) { tipc_set_portunreturnable(portref, 1); if (sock->type == SOCK_DGRAM) diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c index 8c01ccd3626..8f8d0a6c1c1 100644 --- a/net/tipc/subscr.c +++ b/net/tipc/subscr.c @@ -474,6 +474,7 @@ static void subscr_named_msg_event(void *usr_handle, kfree(subscriber); return; } + spin_unlock_bh(subscriber->lock); /* Establish a connection to subscriber */ -- 2.41.1