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SubjectRe: Regression associated with commit c8628155ece3 - "tcp: reduce out_of_order memory use"
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On Fri, 2012-08-24 at 18:18 +0200, Eric Dumazet wrote:
> 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.
>

Try the following patch for a start

diff --git a/drivers/staging/rtl8712/rtl8712_recv.c b/drivers/staging/rtl8712/rtl8712_recv.c
index 8e82ce2..88e3ca6 100644
--- a/drivers/staging/rtl8712/rtl8712_recv.c
+++ b/drivers/staging/rtl8712/rtl8712_recv.c
@@ -1127,6 +1127,9 @@ static void recv_tasklet(void *priv)
recvbuf2recvframe(padapter, pskb);
skb_reset_tail_pointer(pskb);
pskb->len = 0;
- skb_queue_tail(&precvpriv->free_recv_skb_queue, pskb);
+ if (!skb_cloned(pskb))
+ skb_queue_tail(&precvpriv->free_recv_skb_queue, pskb);
+ else
+ consume_skb(pskb);
}
}



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