[PATCH] uml: networking - clear transport-specific structure

Pre-clear transport-specific private structure before passing it down.

In fact, I just got a slab corruption and kernel panic on exit because kfree()
was called on a pointer which probably was never allocated, BUT hadn't been
set to NULL by the driver.

As the code is full of such errors, I've decided for now to go the safe way
(we're talking about drivers), and to do the simple thing.  I'm also starting
to fix drivers, and already sent a patch for the daemon transport.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/drivers/net_kern.c

@@ -317,6 +317,11 @@ static int eth_configure(int n, void *init, char *mac,
 		return 1;
 	}
 
+	lp = dev->priv;
+	/* This points to the transport private data. It's still clear, but we
+	 * must memset it to 0 *now*. Let's help the drivers. */
+	memset(lp, 0, size);
+
 	/* sysfs register */
 	if (!driver_registered) {
 		platform_driver_register(&uml_net_driver);
@@ -358,7 +363,6 @@ static int eth_configure(int n, void *init, char *mac,
 		free_netdev(dev);
 		return 1;
 	}
-	lp = dev->priv;
 
 	/* lp.user is the first four bytes of the transport data, which
 	 * has already been initialized.  This structure assignment will