linux-kernel - Re: [PATCH] fs - fix name overwrite in __register_chrdev

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Message-Id: <20081215215706.7707315c.akpm@linux-foundation.org>
Date:	Mon, 15 Dec 2008 21:57:06 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Alexander Viro <aviro@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs - fix name overwrite in __register_chrdev_region

On Sun, 14 Dec 2008 00:49:11 +0300 Cyrill Gorcunov <gorcunov@...il.com> wrote:

> It's possible to register chdev with a name size
> exactly the same as was allocated in structure.
> It seems it was not intedned behaviour.
> 
> At least chrdev_show does not like it.
> 
> Signed-off-by: Cyrill Gorcunov <gorcunov@...il.com>
> ---
> 
>  fs/char_dev.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: linux-2.6.git/fs/char_dev.c
> ===================================================================
> --- linux-2.6.git.orig/fs/char_dev.c
> +++ linux-2.6.git/fs/char_dev.c
> @@ -120,7 +120,7 @@ __register_chrdev_region(unsigned int ma
>  	cd->major = major;
>  	cd->baseminor = baseminor;
>  	cd->minorct = minorct;
> -	strncpy(cd->name,name, 64);
> +	strncpy(cd->name, name, sizeof(cd->name) - 1);
>  
>  	i = major_to_index(major);
>  

OK.

strlcpy() prodces a more pleasing result:

--- a/fs/char_dev.c~fs-fix-name-overwrite-in-__register_chrdev_region
+++ a/fs/char_dev.c
@@ -120,7 +120,7 @@ __register_chrdev_region(unsigned int ma
 	cd->major = major;
 	cd->baseminor = baseminor;
 	cd->minorct = minorct;
-	strncpy(cd->name,name, 64);
+	strlcpy(cd->name, name, sizeof(cd->name));
 
 	i = major_to_index(major);
 
_

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