From: Sunil Muthuswamy sunilmut@microsoft.com
commit d5afa82c977ea06f7119058fa0eb8519ea501031 upstream.
The current vsock code for removal of socket from the list is both subject to race and inefficient. It takes the lock, checks whether the socket is in the list, drops the lock and if the socket was on the list, deletes it from the list. This is subject to race because as soon as the lock is dropped once it is checked for presence, that condition cannot be relied upon for any decision. It is also inefficient because if the socket is present in the list, it takes the lock twice.
Signed-off-by: Sunil Muthuswamy sunilmut@microsoft.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/vmw_vsock/af_vsock.c | 38 +++++++------------------------------- 1 file changed, 7 insertions(+), 31 deletions(-)
--- a/net/vmw_vsock/af_vsock.c +++ b/net/vmw_vsock/af_vsock.c @@ -279,7 +279,8 @@ EXPORT_SYMBOL_GPL(vsock_insert_connected void vsock_remove_bound(struct vsock_sock *vsk) { spin_lock_bh(&vsock_table_lock); - __vsock_remove_bound(vsk); + if (__vsock_in_bound_table(vsk)) + __vsock_remove_bound(vsk); spin_unlock_bh(&vsock_table_lock); } EXPORT_SYMBOL_GPL(vsock_remove_bound); @@ -287,7 +288,8 @@ EXPORT_SYMBOL_GPL(vsock_remove_bound); void vsock_remove_connected(struct vsock_sock *vsk) { spin_lock_bh(&vsock_table_lock); - __vsock_remove_connected(vsk); + if (__vsock_in_connected_table(vsk)) + __vsock_remove_connected(vsk); spin_unlock_bh(&vsock_table_lock); } EXPORT_SYMBOL_GPL(vsock_remove_connected); @@ -323,35 +325,10 @@ struct sock *vsock_find_connected_socket } EXPORT_SYMBOL_GPL(vsock_find_connected_socket);
-static bool vsock_in_bound_table(struct vsock_sock *vsk) -{ - bool ret; - - spin_lock_bh(&vsock_table_lock); - ret = __vsock_in_bound_table(vsk); - spin_unlock_bh(&vsock_table_lock); - - return ret; -} - -static bool vsock_in_connected_table(struct vsock_sock *vsk) -{ - bool ret; - - spin_lock_bh(&vsock_table_lock); - ret = __vsock_in_connected_table(vsk); - spin_unlock_bh(&vsock_table_lock); - - return ret; -} - void vsock_remove_sock(struct vsock_sock *vsk) { - if (vsock_in_bound_table(vsk)) - vsock_remove_bound(vsk); - - if (vsock_in_connected_table(vsk)) - vsock_remove_connected(vsk); + vsock_remove_bound(vsk); + vsock_remove_connected(vsk); } EXPORT_SYMBOL_GPL(vsock_remove_sock);
@@ -482,8 +459,7 @@ static void vsock_pending_work(struct wo * incoming packets can't find this socket, and to reduce the reference * count. */ - if (vsock_in_connected_table(vsk)) - vsock_remove_connected(vsk); + vsock_remove_connected(vsk);
sk->sk_state = SS_FREE;