linux-kernel - Re: [PATCH] Documentation: laptops: freefall.c: Cleaning up missing null-terminate in conjunction with strncpy

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Message-ID: <53D58550.6040205@infradead.org>
Date:	Sun, 27 Jul 2014 16:03:44 -0700
From:	Randy Dunlap <rdunlap@...radead.org>
To:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
CC:	Pavel Machek <pavel@....cz>,
	Pali Rohár <pali.rohar@...il.com>,
	Stefan Weil <sw@...lnetz.de>, Jiri Kosina <jkosina@...e.cz>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Documentation: laptops: freefall.c:  Cleaning up missing
 null-terminate in conjunction with strncpy

On 07/27/14 07:40, Rickard Strandqvist wrote:
> Added a guaranteed null-terminate after call to strncpy.
> 
> Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
> ---
>  Documentation/laptops/freefall.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/laptops/freefall.c b/Documentation/laptops/freefall.c
> index aab2ff0..113d004 100644
> --- a/Documentation/laptops/freefall.c
> +++ b/Documentation/laptops/freefall.c
> @@ -33,8 +33,10 @@ static int set_unload_heads_path(char *device)
>  
>  	if (strlen(device) <= 5 || strncmp(device, "/dev/", 5) != 0)
>  		return -EINVAL;
> -	strncpy(devname, device + 5, sizeof(devname) - 1);
> -	strncpy(device_path, device, sizeof(device_path) - 1);

Maybe I am overlooking something here, but what was wrong with
the - 1 (2 times) above?  and then just add the 2 lines below that set the
last byte to '\0'?

> +	strncpy(devname, device + 5, sizeof(devname));
> +	devname[sizeof(devname) - 1] = '\0';
> +	strncpy(device_path, device, sizeof(device_path));
> +	device_path[sizeof(device_path) - 1] = '\0';
>  
>  	snprintf(unload_heads_path, sizeof(unload_heads_path) - 1,
>  				"/sys/block/%s/device/unload_heads", devname);
> 


-- 
~Randy
--
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