linux-kernel - Re: kmemcheck detected possible information leak to userspace?

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Message-ID: <20080701112106.GB17015@2ka.mipt.ru>
Date:	Tue, 1 Jul 2008 15:21:06 +0400
From:	Evgeniy Polyakov <johnpol@....mipt.ru>
To:	Vegard Nossum <vegard.nossum@...il.com>
Cc:	netdev@...r.kernel.org, Pekka Enberg <penberg@...helsinki.fi>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: kmemcheck detected possible information leak to userspace?

On Tue, Jul 01, 2008 at 12:52:53PM +0200, Vegard Nossum (vegard.nossum@...il.com) wrote:
> The u means uninitialized. So it seems not to be just the end. But I
> am not sure where the end of the buffer is anyway.
> 
> But there is one thing I forgot: Is this memory initialized by DMA? If
> so, the warning is bogus and I will go hide in shame.

It depends on driver, but sufficiently new hardware (or better say any
non-crappy hardware) will do dma transafer just into skb->data.

To catch it you can put kmemcheck hooks into pci_map* and friend
functions.

-- 
	Evgeniy Polyakov
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