x25: Do not reference freed memory.

commit 96642d42f076101ba98866363d908cab706d156c upstream.

In x25_link_free(), we destroy 'nb' before dereferencing
'nb->dev'.  Don't do this, because 'nb' might be freed
by then.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Tested-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

diff --git a/net/x25/x25_link.c b/net/x25/x25_link.c
index b25c6463c3e996cf536454603f4f0257f3b8b51c..88048b6b0b2bd5e65e08d4c3e07c266995ca7d4c 100644 (file)
--- a/net/x25/x25_link.c
+++ b/net/x25/x25_link.c
@@ -392,9 +392,12 @@ void __exit x25_link_free(void)
        write_lock_bh(&x25_neigh_list_lock);
 
        list_for_each_safe(entry, tmp, &x25_neigh_list) {
+               struct net_device *dev;
+
                nb = list_entry(entry, struct x25_neigh, node);
+               dev = nb->dev;
                __x25_remove_neigh(nb);
-               dev_put(nb->dev);
+               dev_put(dev);
        }
        write_unlock_bh(&x25_neigh_list_lock);
 }