Fix IPX module unload

[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: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/ipx/af_ipx.c b/net/ipx/af_ipx.c
index 76c661566dfdaa1e6eb0cb0f3a5d94db0d97ea2a..89f283c51dff7314e2ff6f97ba565618617d7df3 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);