linux-kernel - Re: [held lock freed] Re: [GIT] Networking

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Date:	Mon, 21 Mar 2011 15:55:32 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Ingo Molnar <mingo@...e.hu>, David Miller <davem@...emloft.net>,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [held lock freed] Re: [GIT] Networking

Le lundi 21 mars 2011 à 15:50 +0100, Arnd Bergmann a écrit :
> On Monday 21 March 2011, Eric Dumazet wrote:
> > [PATCH] ipx: fix ipx_release()
> > 
> > Commit b0d0d915d1d1a0 (remove the BKL) added a regression, because
> > sock_put() can free memory while we are going to use it later.
> > 
> > Fix is to delay sock_put() after release_sock().
> > 
> > Reported-by: Ingo Molnar <mingo@...e.hu>
> > Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
> > Cc: Arnd Bergmann <arnd@...db.de>
> 
> Your fix looks good, thanks Eric!
> 
> Acked-by: Arnd Bergmann <arnd@...db.de>
> 
> I believe I made the same mistake in atalk_release and x25_release:
> 
> 8<------------
> net: fix atalk_release and x25_release
> 
> The recent BKL removal has introduced a use-after-free problem
> in multiple network protocols. This fixes the problem in appletalk
> and x25 by ensuring that we call the final sock_put() after
> releasing the socket lock.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>


> diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
> index 4680b1e..b2cf1db 100644
> --- a/net/x25/af_x25.c
> +++ b/net/x25/af_x25.c
> @@ -669,8 +669,8 @@ static int x25_release(struct socket *sock)
>  
>  	sock_orphan(sk);
>  out:
> -	release_sock(sk);
>  	sock_put(sk);
> +	release_sock(sk);
>  	return 0;
>  }
>  

Hmm, x25_release() looks fine, I believe no fix is needed.




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