Date: Sun, 14 Jan 2018 09:29:06 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r327959 - in stable/11/sys: amd64/amd64 i386/i386 Message-ID: <201801140929.w0E9T6nP056378@repo.freebsd.org>
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Author: kib Date: Sun Jan 14 09:29:06 2018 New Revision: 327959 URL: https://svnweb.freebsd.org/changeset/base/327959 Log: MFC r327816, r327834: Update comment explaining the check, to reality. Modified: stable/11/sys/amd64/amd64/support.S stable/11/sys/i386/i386/support.s Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/amd64/amd64/support.S ============================================================================== --- stable/11/sys/amd64/amd64/support.S Sun Jan 14 06:03:40 2018 (r327958) +++ stable/11/sys/amd64/amd64/support.S Sun Jan 14 09:29:06 2018 (r327959) @@ -225,12 +225,11 @@ ENTRY(copyout) jz done_copyout /* - * Check explicitly for non-user addresses. If 486 write protection - * is being used, this check is essential because we are in kernel - * mode so the h/w does not provide any protection against writing - * kernel addresses. + * Check explicitly for non-user addresses. This check is essential + * because it prevents usermode from writing into the kernel. We do + * not verify anywhere else that the user did not specify a rogue + * address. */ - /* * First, prevent address wrapping. */ Modified: stable/11/sys/i386/i386/support.s ============================================================================== --- stable/11/sys/i386/i386/support.s Sun Jan 14 06:03:40 2018 (r327958) +++ stable/11/sys/i386/i386/support.s Sun Jan 14 09:29:06 2018 (r327959) @@ -284,12 +284,11 @@ ENTRY(copyout) jz done_copyout /* - * Check explicitly for non-user addresses. If 486 write protection - * is being used, this check is essential because we are in kernel - * mode so the h/w does not provide any protection against writing - * kernel addresses. + * Check explicitly for non-user addresses. This check is essential + * because it prevents usermode from writing into the kernel. We do + * not verify anywhere else that the user did not specify a rogue + * address. */ - /* * First, prevent address wrapping. */
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