linux-kernel - Re: [PATCH] strncpy() will not \0 terminate result

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Date:	Fri, 14 Jan 2011 00:25:17 +0000
From:	Tony Finch <dot@...at.at>
To:	Jesper Juhl <jj@...osbits.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] strncpy() will not \0 terminate result

This patch is incorrect. The strncpy is replacing "else" with "if  " so needs to copy exactly 4 bytes.

Tony.
--
f.anthony.n.finch  <dot@...at.at>  http://dotat.at/

On 13 Jan 2011, at 22:35, Jesper Juhl <jj@...osbits.net> wrote:

> Hi,
> 
> Mpass() in scripts/unifdef.c has this code:
>  strncpy(keyword, "if  ", 4);
> this will fail to \0 terminate the destination.
> Following patch should fix that up.
> 
> Signed-off-by: Jesper Juhl <jj@...osbits.net>
> ---
> unifdef.c |    2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/unifdef.c b/scripts/unifdef.c
> index 44d3978..d579249 100644
> --- a/scripts/unifdef.c
> +++ b/scripts/unifdef.c
> @@ -376,7 +376,7 @@ static void Idrop (void) { Fdrop();  ignoreon(); }
> static void Itrue (void) { Ftrue();  ignoreon(); }
> static void Ifalse(void) { Ffalse(); ignoreon(); }
> /* edit this line */
> -static void Mpass (void) { strncpy(keyword, "if  ", 4); Pelif(); }
> +static void Mpass (void) { strncpy(keyword, "if  ", 5); Pelif(); }
> static void Mtrue (void) { keywordedit("else\n");  state(IS_TRUE_MIDDLE); }
> static void Melif (void) { keywordedit("endif\n"); state(IS_FALSE_TRAILER); }
> static void Melse (void) { keywordedit("endif\n"); state(IS_FALSE_ELSE); }
> 
> -- 
> Jesper Juhl <jj@...osbits.net>            http://www.chaosbits.net/
> Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html
> Plain text mails only, please.
> 
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