From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v7 07/14] x86/cet/ibt: Add arch_prctl functions for IBT
Date: Fri, 7 Jun 2019 10:07:06 +0200
Message-ID: <20190607080706.GS3419@hirez.programming.kicks-ass.net>
References: <20190606200926.4029-1-yu-cheng.yu@intel.com>
 <20190606200926.4029-8-yu-cheng.yu@intel.com>
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To: Yu-cheng Yu <yu-cheng.yu@intel.com>
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On Thu, Jun 06, 2019 at 01:09:19PM -0700, Yu-cheng Yu wrote:

> +static int handle_bitmap(unsigned long arg2)
> +{
> +	unsigned long addr, size;
> +
> +	if (get_user(addr, (unsigned long __user *)arg2) ||
> +	    get_user(size, (unsigned long __user *)arg2 + 1))
> +		return -EFAULT;
> +
> +	return cet_setup_ibt_bitmap(addr, size);
> +}


> +	/*
> +	 * Allocate legacy bitmap and return address & size to user.
> +	 */
> +	case ARCH_X86_CET_SET_LEGACY_BITMAP:
> +		return handle_bitmap(arg2);

AFAICT it does exactly the opposite of that comment; it gets the address
and size from userspace and doesn't allocate anything at all.