[src/netbsd-8]: src/sys/arch/amd64/amd64 Pull up following revision(s) (reque...

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

details:   https://anonhg.NetBSD.org/src/rev/a0522c2a2301
branches:  netbsd-8
changeset: 851576:a0522c2a2301
user:      snj <snj%NetBSD.org@localhost>
date:      Sun Apr 08 06:14:18 2018 +0000

description:
Pull up following revision(s) (requested by maxv in ticket #705):
        sys/arch/amd64/amd64/trap.c: 1.113
Mmh. We shouldn't read %cr2 here. %cr2 is initialized by the CPU only
during page faults (T_PAGEFLT), so here we're reading a value that comes
from a previous page fault.
That's a real problem; if you launch an unprivileged process, set up a
signal handler, make it sleep 10 seconds, and trigger a T_ALIGNFLT fault,
you get in si_addr the address of another LWP's page - and perhaps this
can be used to defeat userland ASLR.
This bug has been there since 2003.

diffstat:

 sys/arch/amd64/amd64/trap.c |  6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diffs (27 lines):

diff -r e2337fbdd840 -r a0522c2a2301 sys/arch/amd64/amd64/trap.c
--- a/sys/arch/amd64/amd64/trap.c       Sun Apr 08 06:12:53 2018 +0000
+++ b/sys/arch/amd64/amd64/trap.c       Sun Apr 08 06:14:18 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: trap.c,v 1.96.4.2 2018/03/22 16:59:03 martin Exp $     */
+/*     $NetBSD: trap.c,v 1.96.4.3 2018/04/08 06:14:18 snj Exp $        */
 
 /*-
  * Copyright (c) 1998, 2000 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.96.4.2 2018/03/22 16:59:03 martin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.96.4.3 2018/04/08 06:14:18 snj Exp $");
 
 #include "opt_ddb.h"
 #include "opt_kgdb.h"
@@ -389,7 +389,7 @@
 #endif
                KSI_INIT_TRAP(&ksi);
                ksi.ksi_trap = type & ~T_USER;
-               ksi.ksi_addr = (void *)rcr2();
+               ksi.ksi_addr = (void *)frame->tf_rip;
                switch (type) {
                case T_SEGNPFLT|T_USER:
                case T_STKFLT|T_USER: