Re: [PATCH 2/2] mkiss: Fix use after free in sixpack_close().

[David Miller]

From: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Date: Thu, 17 Dec 2015 22:35:31 +0100

> On Thu, Dec 17, 2015 at 04:05:49PM -0500, David Miller wrote:
> 
>> Subject: [PATCH 2/2] mkiss: Fix use after free in sixpack_close().
> 
> Make that subject "... mkiss_close()."

Durrr... indeed.  Thanks for catching that.

Committed as follows:

====================
[PATCH] mkiss: Fix use after free in mkiss_close().

Need to do the unregister_device() after all references to the driver
private have been done.

Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
---
 drivers/net/hamradio/mkiss.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index 216bfd3..0b72b9d 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -798,13 +798,13 @@ static void mkiss_close(struct tty_struct *tty)
 	if (!atomic_dec_and_test(&ax->refcnt))
 		down(&ax->dead_sem);
 
-	unregister_netdev(ax->dev);
-
 	/* Free all AX25 frame buffers. */
 	kfree(ax->rbuff);
 	kfree(ax->xbuff);
 
 	ax->tty = NULL;
+
+	unregister_netdev(ax->dev);
 }
 
 /* Perform I/O control on an active ax25 channel. */
-- 
2.4.1

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