Re: [PATCH v2] usbnet: remove generic hard_header_len check

[David Miller]

From: Emil Goode <emilgoode@xxxxxxxxx>
Date: Thu, 13 Feb 2014 17:50:19 +0100

> This patch removes a generic hard_header_len check from the usbnet
> module that is causing dropped packages under certain circumstances
> for devices that send rx packets that cross urb boundaries.
> 
> One example is the AX88772B which occasionally send rx packets that
> cross urb boundaries where the remaining partial packet is sent with
> no hardware header. When the buffer with a partial packet is of less
> number of octets than the value of hard_header_len the buffer is
> discarded by the usbnet module.
> 
> With AX88772B this can be reproduced by using ping with a packet
> size between 1965-1976.
> 
> The bug has been reported here:
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=29082
> 
> This patch introduces the following changes:
> - Removes the generic hard_header_len check in the rx_complete
>   function in the usbnet module.
> - Introduces a ETH_HLEN check for skbs that are not cloned from
>   within a rx_fixup callback.
> - For safety a hard_header_len check is added to each rx_fixup
>   callback function that could be affected by this change.
>   These extra checks could possibly be removed by someone
>   who has the hardware to test.
> - Removes a call to dev_kfree_skb_any() and instead utilizes the
>   dev->done list to queue skbs for cleanup.
> 
> The changes place full responsibility on the rx_fixup callback
> functions that clone skbs to only pass valid skbs to the
> usbnet_skb_return function.
> 
> Signed-off-by: Emil Goode <emilgoode@xxxxxxxxx>
> Reported-by: Igor Gnatenko <i.gnatenko.brain@xxxxxxxxx>

Applied and queued up for -stable, thanks.
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