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Date: Mon, 19 Sep 2011 14:20:43 -0700
From: Andrew Morton <akpm@google.com>
To: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: linux-security-module@vger.kernel.org,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        David Safford <safford@watson.ibm.com>,
        "Nicholas A. Bellinger" <nab@linux-iscsi.org>,
        target-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH 2/5] lib: add error checking to hex2bin
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On Fri, 16 Sep 2011 08:50:27 -0400
Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:

> --- a/lib/hexdump.c
> +++ b/lib/hexdump.c
> @@ -38,14 +38,17 @@ EXPORT_SYMBOL(hex_to_bin);
>   * @dst: binary result
>   * @src: ascii hexadecimal string
>   * @count: result length
> + *
> + * Returns true on success, false in case of bad input.
>   */
> -void hex2bin(u8 *dst, const char *src, size_t count)
> +bool hex2bin(u8 *dst, const char *src, size_t count)
>  {
>  	while (count--) {
> -		*dst = hex_to_bin(*src++) << 4;
> -		*dst += hex_to_bin(*src++);
> -		dst++;
> +		if (!unpack_hex_byte(dst++, src))
> +			return false;
> +		src += 2;
>  	}
> +	return true;
>  }
>  EXPORT_SYMBOL(hex2bin);

Again, this is very unconventional for kernel code, and it's for no good
reason.  Please, stick with 0/-1 unless there's a good reason to diverge
from that.