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Date: Wed, 06 Oct 2010 10:16:10 +0200
From: walter harms <wharms@bfs.de>
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To: Dan Carpenter <error27@gmail.com>, Armin Schindler <armin@melware.de>,
        Karsten Keil <isdn@linux-pingi.de>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [patch] eicon: make buffer larger
References: <20101004192459.GE5692@bicker> <alpine.DEB.2.00.1010060923120.29107@justus.melware.de> <20101006074714.GE5409@bicker>
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Dan Carpenter schrieb:
> On Wed, Oct 06, 2010 at 09:25:44AM +0200, Armin Schindler wrote:
>> On Mon, 4 Oct 2010, Dan Carpenter wrote:
>>> In diva_mnt_add_xdi_adapter() we do this:
>>>  strcpy (clients[id].drvName,     tmp);
>>>  strcpy (clients[id].Dbg.drvName, tmp);
>>>
>>> The "clients[id].drvName" is a 128 character buffer and
>>> "clients[id].Dbg.drvName" was originally a 16 character buffer but I've
>>> changed it to 128 as well.  We don't actually use 128 characters but we
>>> do use more than 16.
>> I don't see any reason for that change. The driver names here do not use  
>> more than 16 characters and when filled, the length is checked anyway.
>> Please avoid changing the size of that structure.
>>
> 
> drivers/isdn/hardware/eicon/debug.c diva_mnt_add_xdi_adapter()
>    874      sprintf (tmp, "ADAPTER:%d SN:%u-%d",
>                            12345678 90123 45 67
> 
> 	That's a minimum 17 characters.
> 
>    875               (int)logical,
>    876               serial & 0x00ffffff,
>    877               (byte)(((serial & 0xff000000) >> 24) + 1));
>    878    } else {
>    879      sprintf (tmp, "ADAPTER:%d SN:%u", (int)logical, serial);
>    880    }
> 


for that reason i am a fan of kasprintf().
Maybe this a solution here also ? samething like:

kasprintf (&buf, "ADAPTER:%d SN:%u-%d",12345678,90123,45,67):
...
kstrncpy(tmp,buf,sizeof(buf));
....
free(buf);

that would keep overflows away until the changes in the structure are ready.

re,
 wh