linux-kernel - Re: [PATCH] mm/zpool: use prefixed module loading

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Date:	Fri, 8 Aug 2014 09:23:54 -0500
From:	Seth Jennings <sjennings@...iantweb.net>
To:	Kees Cook <keescook@...omium.org>
Cc:	linux-kernel@...r.kernel.org, Minchan Kim <minchan@...nel.org>,
	Nitin Gupta <ngupta@...are.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Streetman <ddstreet@...e.org>,
	Dan Carpenter <dan.carpenter@...cle.com>, linux-mm@...ck.org
Subject: Re: [PATCH] mm/zpool: use prefixed module loading

On Fri, Aug 08, 2014 at 12:53:16AM -0700, Kees Cook wrote:
> To avoid potential format string expansion via module parameters,
> do not use the zpool type directly in request_module() without a
> format string. Additionally, to avoid arbitrary modules being loaded
> via zpool API (e.g. via the zswap_zpool_type module parameter) add a
> "zpool-" prefix to the requested module, as well as module aliases for
> the existing zpool types (zbud and zsmalloc).

I didn't know that request_module() did string expansion.
Thanks for the fix!

Acked-by: Seth Jennings <sjennings@...iantweb.net>

> 
> Signed-off-by: Kees Cook <keescook@...omium.org>
> ---
>  mm/zbud.c     | 1 +
>  mm/zpool.c    | 2 +-
>  mm/zsmalloc.c | 1 +
>  3 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/zbud.c b/mm/zbud.c
> index a05790b1915e..aa74f7addab1 100644
> --- a/mm/zbud.c
> +++ b/mm/zbud.c
> @@ -619,3 +619,4 @@ module_exit(exit_zbud);
>  MODULE_LICENSE("GPL");
>  MODULE_AUTHOR("Seth Jennings <sjenning@...ux.vnet.ibm.com>");
>  MODULE_DESCRIPTION("Buddy Allocator for Compressed Pages");
> +MODULE_ALIAS("zpool-zbud");
> diff --git a/mm/zpool.c b/mm/zpool.c
> index e40612a1df00..739cdf0d183a 100644
> --- a/mm/zpool.c
> +++ b/mm/zpool.c
> @@ -150,7 +150,7 @@ struct zpool *zpool_create_pool(char *type, gfp_t gfp, struct zpool_ops *ops)
>  	driver = zpool_get_driver(type);
>  
>  	if (!driver) {
> -		request_module(type);
> +		request_module("zpool-%s", type);
>  		driver = zpool_get_driver(type);
>  	}
>  
> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
> index 4e2fc83cb394..36af729eb3f6 100644
> --- a/mm/zsmalloc.c
> +++ b/mm/zsmalloc.c
> @@ -1199,3 +1199,4 @@ module_exit(zs_exit);
>  
>  MODULE_LICENSE("Dual BSD/GPL");
>  MODULE_AUTHOR("Nitin Gupta <ngupta@...are.org>");
> +MODULE_ALIAS("zpool-zsmalloc");
> -- 
> 1.9.1
> 
> 
> -- 
> Kees Cook
> Chrome OS Security
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