linux-kernel - Re: [Patch] quota: do not leak info to user-space

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Message-ID: <20130513100423.GD400@quack.suse.cz>
Date:	Mon, 13 May 2013 12:04:23 +0200
From:	Jan Kara <jack@...e.cz>
To:	Cong Wang <amwang@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jan Kara <jack@...e.cz>, xfs@....sgi.com
Subject: Re: [Patch] quota: do not leak info to user-space

On Fri 10-05-13 17:24:33, Cong Wang wrote:
> From: Cong Wang <amwang@...hat.com>
> 
> There is a hole in struct fs_quota_stat, so we have to
> zero the struct on stack before copying it to user-space.
> 
> Cc: Jan Kara <jack@...e.cz>
> Signed-off-by: Cong Wang <amwang@...hat.com>
  Good point. I've merged the patch.

BTW for XFS folks: The structure definition looks somewhat odd (unaligned
definition of qs_flags, qs_uquota starts only at 32-bit boundary although
it has 64-bit fields in it) and I wouldn't be surprised if it needed compat
wrapper for 32-bit apps on some architectures...

								Honza
> 
> ---
> diff --git a/fs/quota/quota.c b/fs/quota/quota.c
> index c7314f1..2b0c182 100644
> --- a/fs/quota/quota.c
> +++ b/fs/quota/quota.c
> @@ -211,6 +211,7 @@ static int quota_getxstate(struct super_block *sb, void __user *addr)
>  
>  	if (!sb->s_qcop->get_xstate)
>  		return -ENOSYS;
> +	memset(&fqs, 0, sizeof(fqs));
>  	ret = sb->s_qcop->get_xstate(sb, &fqs);
>  	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
>  		return -EFAULT;
-- 
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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