linux-kernel - Re: [PATCH 3/3] net: tipc: fix information leak to userland

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Message-ID: <20101109203317.GA24933@albatros>
Date:	Tue, 9 Nov 2010 23:33:18 +0300
From:	Vasiliy Kulikov <segooon@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	kernel-janitors@...r.kernel.org, jon.maloy@...csson.com,
	allan.stephens@...driver.com,
	tipc-discussion@...ts.sourceforge.net, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] net: tipc: fix information leak to userland

On Tue, Nov 09, 2010 at 09:26 -0800, David Miller wrote:
> From: Vasiliy Kulikov <segooon@...il.com>
> Date: Sun, 31 Oct 2010 20:10:32 +0300
> 
> > Structure sockaddr_tipc is copied to userland with padding bytes after
> > "id" field in union field "name" unitialized.  It leads to leaking of
> > contents of kernel stack memory.  We have to initialize them to zero.
> > 
> > Signed-off-by: Vasiliy Kulikov <segooon@...il.com>
> 
> Applied.
> 
> Patches #1 and #2 were given feedback which I need you to integrate
> and submit new patches based upon, thanks.

About #2:

I still think that this:

    if (dev)
        strncpy(uaddr->sa_data, dev->name, 14);
    else
        memset(uaddr->sa_data, 0, 14);

is better than this:

    memset(uaddr->sa_data, 0, 14);
    dev = dev_get_by_index_rcu(sock_net(sk), pkt_sk(sk)->ifindex);
    if (dev)
        strlcpy(uaddr->sa_data, dev->name, 15);

Doesn't it?  Explicitly filling with zero on the same "if" level is
slightly easier to read and understand.

-- 
Vasiliy
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