[src/trunk]: src/sys/arch Put two KASSERTs, to make sure the fault is happeni...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/1cf1d7f515f2
branches:  trunk
changeset: 817923:1cf1d7f515f2
user:      maxv <maxv%NetBSD.org@localhost>
date:      Fri Sep 16 11:48:10 2016 +0000

description:
Put two KASSERTs, to make sure the fault is happening in the correct
half of the vm space when using special copy functions. It can detect
bugs where the kernel would fault when copying a kernel buffer which
it wrongly believes comes from userland.

diffstat:

 sys/arch/amd64/amd64/trap.c |  8 ++++++--
 sys/arch/i386/i386/trap.c   |  8 ++++++--
 2 files changed, 12 insertions(+), 4 deletions(-)

diffs (58 lines):

diff -r bcf06fd4b7c5 -r 1cf1d7f515f2 sys/arch/amd64/amd64/trap.c
--- a/sys/arch/amd64/amd64/trap.c       Fri Sep 16 11:41:40 2016 +0000
+++ b/sys/arch/amd64/amd64/trap.c       Fri Sep 16 11:48:10 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: trap.c,v 1.84 2016/08/11 14:58:29 maxv Exp $   */
+/*     $NetBSD: trap.c,v 1.85 2016/09/16 11:48:10 maxv Exp $   */
 
 /*-
  * Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.84 2016/08/11 14:58:29 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.85 2016/09/16 11:48:10 maxv Exp $");
 
 #include "opt_ddb.h"
 #include "opt_kgdb.h"
@@ -310,6 +310,10 @@
 copyefault:
                        error = EFAULT;
 copyfault:
+                       KASSERT(onfault == kcopy_fault ||
+                           rcr2() < VM_MAXUSER_ADDRESS);
+                       KASSERT(onfault != kcopy_fault ||
+                           rcr2() >= VM_MAXUSER_ADDRESS);
                        frame->tf_rip = (uintptr_t)onfault;
                        frame->tf_rax = error;
                        return;
diff -r bcf06fd4b7c5 -r 1cf1d7f515f2 sys/arch/i386/i386/trap.c
--- a/sys/arch/i386/i386/trap.c Fri Sep 16 11:41:40 2016 +0000
+++ b/sys/arch/i386/i386/trap.c Fri Sep 16 11:48:10 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: trap.c,v 1.278 2016/08/11 15:03:23 maxv Exp $  */
+/*     $NetBSD: trap.c,v 1.279 2016/09/16 11:48:10 maxv Exp $  */
 
 /*-
  * Copyright (c) 1998, 2000, 2005, 2006, 2007, 2008 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.278 2016/08/11 15:03:23 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.279 2016/09/16 11:48:10 maxv Exp $");
 
 #include "opt_ddb.h"
 #include "opt_kgdb.h"
@@ -354,6 +354,10 @@
 copyefault:
                        error = EFAULT;
 copyfault:
+                       KASSERT(onfault == kcopy_fault ||
+                           rcr2() < VM_MAXUSER_ADDRESS);
+                       KASSERT(onfault != kcopy_fault ||
+                           rcr2() >= VM_MAXUSER_ADDRESS);
                        frame->tf_eip = (uintptr_t)onfault;
                        frame->tf_eax = error;
                        return;