[patch 036/101] Fix IPX module unload

[Greg KH]

From: Jiri Bohac <jbohac@xxxxxxx>

[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@xxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 net/ipx/af_ipx.c |   26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

--- linux-2.6.20.1.orig/net/ipx/af_ipx.c
+++ linux-2.6.20.1/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;
-
-	unregister_8022_client(p8022_datalink);
-	p8022_datalink = NULL;
+	if (pSNAP_datalink) {
+		unregister_snap_client(pSNAP_datalink);
+		pSNAP_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);

--
-
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