Re: [PATCH v7 07/14] x86/cet/ibt: Add arch_prctl functions for IBT

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.