[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>

1 files changed, 16 insertions, 8 deletions

diff --git a/net/ipx/af_ipx.c b/net/ipx/af_ipx.c
index 76c661566dfd..89f283c51dff 100644
--- 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);