linux-kernel - Re: [PATCH] atmel: using strlcpy() to avoid possible buffer overflows

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Date:   Sat, 30 Jun 2018 00:51:49 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     YueHaibing <yuehaibing@...wei.com>
Cc:     simon@...kelleys.org.uk, Kalle Valo <kvalo@...eaurora.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        "open list:TI WILINK WIRELES..." <linux-wireless@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] atmel: using strlcpy() to avoid possible buffer overflows

On Sat, Jun 30, 2018 at 12:47 AM, Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
> On Fri, Jun 29, 2018 at 5:51 AM, YueHaibing <yuehaibing@...wei.com> wrote:
>> 'firmware' is a module param which may been longer than firmware_id,
>> so using strlcpy() to guard against overflows
>
> strncat() is against overflow, this does a bit more.
>
>>         priv->firmware_id[0] = '\0';
> ...
>>         if (firmware) /* module parameter */
>> -               strcpy(priv->firmware_id, firmware);
>> +               strlcpy(priv->firmware_id, firmware, sizeof(priv->firmware_id));
>
> In either case the above '\0' is not needed.
> But it looks like the intention was to use strncat() / strlcat().

Ah, this is under condition, yes. If no parameter supplied, this needs
to be clean, but
priv is allocated with zeroed memory
https://elixir.bootlin.com/linux/latest/source/net/core/dev.c#L8369

-- 
With Best Regards,
Andy Shevchenko