[IPX]: Fix NULL pointer dereference on ipx unload

Fixes a null pointer dereference when unloading the ipx module.

On initialization of the ipx module, registering certain packet
types can fail. When this happens, unloading the module later
dereferences NULL pointers.  This patch fixes that. Please apply.

Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

diff --git a/net/ipx/af_ipx.c b/net/ipx/af_ipx.c
index 8b0c25f74a43e1f59c301239c629fae54b183293..33f0bbfcb6bdc3e31c06cc2ae3c98196654e6feb 100644 (file)
--- a/net/ipx/af_ipx.c
+++ b/net/ipx/af_ipx.c
@@ -2010,19 +2010,27 @@ static void __exit ipx_proto_finito(void)
 
        ipxitf_cleanup();
 
-       unregister_snap_client(pSNAP_datalink);
-       pSNAP_datalink = NULL;
+       if (pSNAP_datalink) {
+               unregister_snap_client(pSNAP_datalink);
+               pSNAP_datalink = NULL;
+       }
 
-       unregister_8022_client(p8022_datalink);
-       p8022_datalink = NULL;
+       if (p8022_datalink) {
+               unregister_8022_client(p8022_datalink);
+               p8022_datalink = NULL;
+       }
 
        dev_remove_pack(&ipx_8023_packet_type);
-       destroy_8023_client(p8023_datalink);
-       p8023_datalink = NULL;
+       if (p8023_datalink) {
+               destroy_8023_client(p8023_datalink);
+               p8023_datalink = NULL;
+       }
 
        dev_remove_pack(&ipx_dix_packet_type);
-       destroy_EII_client(pEII_datalink);
-       pEII_datalink = NULL;
+       if (pEII_datalink) {
+               destroy_EII_client(pEII_datalink);
+               pEII_datalink = NULL;
+       }
 
        proto_unregister(&ipx_proto);
        sock_unregister(ipx_family_ops.family);