linux-kernel - Re: [PATCH] xfs: Initialize label array properly

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Message-ID: <20190830053945.GX5354@magnolia>
Date:   Thu, 29 Aug 2019 22:39:45 -0700
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Austin Kim <austindh.kim@...il.com>
Cc:     linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xfs: Initialize label array properly

On Fri, Aug 30, 2019 at 02:37:07PM +0900, Austin Kim wrote:
> In case kernel stack variable is not initialized properly,
> there is a risk of kernel information disclosure.
> 
> So, initialize 'char label[]' array with null characters.

Got a testcase for this?  At least a couple other filesystems implement
this ioctl too, which means they all should be checked/tested on a
regular basis.

--D

> Signed-off-by: Austin Kim <austindh.kim@...il.com>
> ---
>  fs/xfs/xfs_ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 9ea5166..09b3bee 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -2037,7 +2037,7 @@ xfs_ioc_setlabel(
>  	char			__user *newlabel)
>  {
>  	struct xfs_sb		*sbp = &mp->m_sb;
> -	char			label[XFSLABEL_MAX + 1];
> +	char			label[XFSLABEL_MAX + 1] = {0};
>  	size_t			len;
>  	int			error;
>  
> -- 
> 2.6.2
>