netdev - Re: [PATCH] USB CDC NCM: Don't deref NULL in cdc_ncm_rx_fixup() and don't use uninitialized variable.

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Date:	Thu, 13 Jan 2011 21:50:28 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	jj@...osbits.net
Cc:	linux-kernel@...r.kernel.org, oliver@...kum.name, gregkh@...e.de,
	linux-usb@...r.kernel.org, netdev@...r.kernel.org,
	alexey.orishko@...ricsson.com, hans.petter.selasky@...ricsson.com
Subject: Re: [PATCH] USB CDC NCM: Don't deref NULL in cdc_ncm_rx_fixup()
 and don't use uninitialized variable.

From: Jesper Juhl <jj@...osbits.net>
Date: Thu, 13 Jan 2011 22:40:11 +0100 (CET)

> skb_clone() dynamically allocates memory and may fail. If it does it 
> returns NULL. This means we'll dereference a NULL pointer in 
> drivers/net/usb/cdc_ncm.c::cdc_ncm_rx_fixup().
> As far as I can tell, the proper way to deal with this is simply to goto 
> the error label.
> 
> Furthermore gcc complains that 'skb' may be used uninitialized:
>   drivers/net/usb/cdc_ncm.c: In function ‘cdc_ncm_rx_fixup’:
>   drivers/net/usb/cdc_ncm.c:922:18: warning: ‘skb’ may be used uninitialized in this function
> and I believe it is right. On the line where we
>   pr_debug("invalid frame detected (ignored)" ...
> we are using the local variable 'skb' but nothing has ever been assigned 
> to that variable yet. I believe the correct fix for that is to use 
> 'skb_in' instead.
> 
> Signed-off-by: Jesper Juhl <jj@...osbits.net>

Applied.