[PATCH 3.18 06/13] vsock: cope with memory allocation failure at socket creation time

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paolo Abeni <pabeni@redhat.com>

[ Upstream commit 225d9464268599a5b4d094d02ec17808e44c7553 ]

In the unlikely event that the kmalloc call in vmci_transport_socket_init()
fails, we end-up calling vmci_transport_destruct() with a NULL vmci_trans()
and oopsing.

This change addresses the above explicitly checking for zero vmci_trans()
at destruction time.

Reported-by: Xiumei Mu <xmu@redhat.com>
Fixes: d021c344051a ("VSOCK: Introduce VM Sockets")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/vmw_vsock/vmci_transport.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/net/vmw_vsock/vmci_transport.c
+++ b/net/vmw_vsock/vmci_transport.c
@@ -1663,6 +1663,10 @@ static int vmci_transport_socket_init(st
 
 static void vmci_transport_destruct(struct vsock_sock *vsk)
 {
+	/* transport can be NULL if we hit a failure at init() time */
+	if (!vmci_trans(vsk))
+		return;
+
 	if (vmci_trans(vsk)->attach_sub_id != VMCI_INVALID_ID) {
 		vmci_event_unsubscribe(vmci_trans(vsk)->attach_sub_id);
 		vmci_trans(vsk)->attach_sub_id = VMCI_INVALID_ID;