[PATCH] ISDN: fix double free bug in isdn_net

[Jesper Juhl <jesper.juhl@gmail.com>]

There's double-free bug in 
drivers/isdn/i4l/isdn_net.c::isdn_net_writebuf_skb().

If isdn_writebuf_skb_stub() doesn't handle the entire skb, then it will 
have freed the skb that was passed to it and when the code then jumps 
to the error label it'll result in a double free of the skb.

The easy way to fix this is to insert an assignment of skb = NULL in the
'if' following the call to isdn_writebuf_skb_stub() so that when the code
at the error label calls dev_kfree_skb(skb); the skb will be NULL and 
nothing will happen since dev_kfree_skb() just does a return if passed a
NULL.


Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
---

 drivers/isdn/i4l/isdn_net.c |    1 +
 1 files changed, 1 insertion(+)

--- linux-2.6.18-rc4-orig/drivers/isdn/i4l/isdn_net.c	2006-08-11 00:10:55.000000000 +0200
+++ linux-2.6.18-rc4/drivers/isdn/i4l/isdn_net.c	2006-08-12 22:39:56.000000000 +0200
@@ -1023,6 +1023,7 @@ void isdn_net_writebuf_skb(isdn_net_loca
 	if (ret != len) {
 		/* we should never get here */
 		printk(KERN_WARNING "%s: HL driver queue full\n", lp->name);
+		skb = NULL;
 		goto error;
 	}