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Date: Fri, 11 May 2018 15:50:46 -0400 (EDT)
Message-Id: <20180511.155046.122041869811590666.davem@davemloft.net>
To: wang6495@umn.edu
Cc: kjlu@umn.edu, mac@melware.de, isdn@linux-pingi.de,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] isdn: eicon: fix a missing-check bug
From: David Miller <davem@davemloft.net>
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From: Wenwen Wang <wang6495@umn.edu>
Date: Sat,  5 May 2018 14:32:46 -0500

> To avoid such issues, this patch adds a check after the second copy in the
> function diva_xdi_write(). If the adapter number is not equal to the one
> obtained in the first copy, (-4) will be returned to divas_write(), which
> will then return an error code -EINVAL.

Better fix is to copy the msg header once into an on-stack buffer supplied
by diva_write() to diva_xdi_open_adapter(), which is then passed on to
diva_xdi_write() with an adjusted src pointer and length.