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Date: Mon, 12 May 2008 16:38:46 -0400
From: Allan Stephens <allan.stephens@...driver.com>
To: David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org, allan.stephens@...driver.com
Subject: [PATCH net-next-2.6] [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 <allan.stephens@...driver.com>
---
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 11105bc..9923e41 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 2f58064..757de38 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 89cbab2..a101de8 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 230f9ca..38f4879 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 8c01ccd..8f8d0a6 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 */
--
1.5.3.2
--
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