netdev - question about frag_can

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Date:	Fri, 30 Mar 2012 23:02:37 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Sven Eckelmann <sven@...fation.org>
Cc:	b.a.t.m.a.n@...ts.open-mesh.org, netdev@...r.kernel.org
Subject: question about frag_can_reassemble()

Hi Sven,

I had a question about the code in frag_can_reassemble().

net/batman-adv/unicast.h
    51  
    52          merged_size = (skb->len - sizeof(*unicast_packet)) * 2;
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    53          merged_size += sizeof(struct unicast_packet) + uneven_correction;
    54  
    55          return merged_size <= mtu;
    56  }

Can the skb->len be less than sizeof(*unicast_packet) (ie 20 bytes)?
If "len" is less than 10 then we would return false but if it's
over 10 then we would return true.  Roughly.

regards,
dan carpenter
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