netdev - Re: [PATCH] 6pack: fix free memory scribbles

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Date:	Wed, 06 Jan 2016 01:25:55 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	gnomes@...rguk.ukuu.org.uk
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] 6pack: fix free memory scribbles

From: Alan <gnomes@...rguk.ukuu.org.uk>
Date: Tue, 05 Jan 2016 11:51:25 +0000

> commit acf673a3187edf72068ee2f92f4dc47d66baed47 fixed a user triggerable free
> memory scribble but in doing so replaced it with a different one that allows
> the user to control the data and scribble even more.
> 
> sixpack_close is called by the tty layer in tty context. The tty context is
> protected by sp_get() and sp_put(). However network layer activity via
> sp_xmit() is not protected this way. We must therefore stop the queue
> otherwise the user gets to dump a buffer mostly of their choice into freed
> kernel pages.
> 
> Signed-off-by: Alan Cox <alan@...ux.intel.com>

Applied, thanks Alan.

> +	/* We must stop the queue to avoid potentially scribbling
> +	   on the free buffers. The sp->dead_sem is not sufficient
> +	   to protect us from sp->xbuff access */

Please next time format comments:

	/* Like
	 * this.
	 */

Thanks again!
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