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

From	David Miller <davem@davemloft.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/2] mkiss: Fix use after free in sixpack_close().
Date	2015-12-18 22:10 +0100
Message-ID	<qHarL-2rz-13@gated-at.bofh.it> (permalink)
References	<qGNYe-4LR-11@gated-at.bofh.it> <qGOrg-4Wi-9@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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From: Ralf Baechle <ralf@linux-mips.org>
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@davemloft.net>
---
 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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[PATCH 2/2] mkiss: Fix use after free in sixpack_close(). David Miller <davem@davemloft.net> - 2015-12-17 22:10 +0100
  Re: [PATCH 2/2] mkiss: Fix use after free in sixpack_close(). Ralf Baechle <ralf@linux-mips.org> - 2015-12-17 22:40 +0100
    Re: [PATCH 2/2] mkiss: Fix use after free in sixpack_close(). David Miller <davem@davemloft.net> - 2015-12-18 22:10 +0100

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