Subject: Re: Regression associated with commit c8628155ece3 - "tcp: reduce
 out_of_order memory use"
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Larry Finger <Larry.Finger@lwfinger.net>
Cc: David Miller <davem@davemloft.net>, ncardwell@google.com,
        linville@tuxdriver.com, linux-wireless@vger.kernel.org,
        linux-kernel@vger.kernel.org
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	 <5037A4B0.3080208@lwfinger.net>
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Date: Fri, 24 Aug 2012 18:18:15 +0200
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On Fri, 2012-08-24 at 10:58 -0500, Larry Finger wrote:
> On 08/24/2012 10:19 AM, David Miller wrote:
> >
> > This looks like full-on data corruption to me.
> 
> I agree. The question is why does it happen with r8712u, and only after the 
> commit in the subject. Drivers for other devices that I have are OK. Thus far, I 
> have tested b43, rtl8187, ath9k_htc, and rtl8192cu. To my knowledge, there are 
> no reports posted for this bug with any other device.

bugs can sit unnoticed, and one change somewhere can uncover them.

Really this driver must have a bug, if not half a dozen of bugs.

For example this sequence of code is a clear bug :

sub_skb = dev_alloc_skb(nSubframe_Length + 12); 
skb_reserve(sub_skb, 12);


Also the free_recv_skb_queue looks really suspect to me

What the hell is doing recv_tasklet() I really wonder.

This code, combined with the skb_clone() in recvbuf2recvframe()
can clearly reuse an skb passed to upper stacks.


queueing one skb in free_recv_skb_queue should be done
only if no clone of this skb exist somewhere.

Please someone fix this buggy driver.


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