[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>

diff --git a/net/ipx/af_ipx.c b/net/ipx/af_ipx.c
index 76c6615..89f283c 100644 (file)
--- a/net/ipx/af_ipx.c
+++ b/net/ipx/af_ipx.c
@@ -2035,19 +2035,27 @@ 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);