[PATCH] Fix NULL pointer dereference on ipx unload

[PATCH] Fix NULL pointer dereference on ipx unload

[Jiri Bohac]

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>

diff -ur linux-2.6.20-rc6/net/ipx/af_ipx.c linux-2.6.20-rc6.fixed/net/ipx/af_ipx.c
--- linux-2.6.20-rc6/net/ipx/af_ipx.c	2007-01-25 03:19:28.000000000 +0100
+++ linux-2.6.20-rc6.fixed/net/ipx/af_ipx.c	2007-02-08 18:13:53.000000000 +0100
@@ -2035,19 +2035,27 @@
 
 	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);


-- 
Jiri Bohac <jbohac@suse.cz>
SUSE Labs, SUSE CZ

Re: [PATCH] Fix NULL pointer dereference on ipx unload

[David Miller]

From: Jiri Bohac <jbohac@suse.cz>
Date: Fri, 9 Feb 2007 00:28:29 +0100

> 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>

Applied, thanks a lot Jiri.