Module Name: src
Committed By: maxv
Date: Sun Feb 25 13:09:34 UTC 2018
Modified Files:
src/sys/arch/amd64/amd64: trap.c
Log Message:
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.
To generate a diff of this commit:
cvs rdiff -u -r1.112 -r1.113 src/sys/arch/amd64/amd64/trap.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/amd64/amd64/trap.c
diff -u src/sys/arch/amd64/amd64/trap.c:1.112 src/sys/arch/amd64/amd64/trap.c:1.113
--- src/sys/arch/amd64/amd64/trap.c:1.112 Sun Feb 25 12:37:16 2018
+++ src/sys/arch/amd64/amd64/trap.c Sun Feb 25 13:09:33 2018
@@ -1,4 +1,4 @@
-/* $NetBSD: trap.c,v 1.112 2018/02/25 12:37:16 maxv Exp $ */
+/* $NetBSD: trap.c,v 1.113 2018/02/25 13:09:33 maxv Exp $ */
/*
* Copyright (c) 1998, 2000, 2017 The NetBSD Foundation, Inc.
@@ -64,7 +64,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.112 2018/02/25 12:37:16 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: trap.c,v 1.113 2018/02/25 13:09:33 maxv Exp $");
#include "opt_ddb.h"
#include "opt_kgdb.h"
@@ -376,7 +376,7 @@ trap(struct trapframe *frame)
case T_ALIGNFLT|T_USER:
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:
