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On amd64, mark the whole tree as NX. No real functional change, just to

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prevent possible future surprises, and to make it a little harder to map
executable pages in ROP chains.
This commit is contained in:
maxv 2020-03-14 05:19:50 +00:00
parent 12fcc7d589
commit 4e27c3180c
1 changed files with 6 additions and 3 deletions
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9
sys/arch/x86/x86/pmap.c
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@ -1,4 +1,4 @@
/* $NetBSD: pmap.c,v 1.363 2020/03/10 22:38:41 ad Exp $ */
/* $NetBSD: pmap.c,v 1.364 2020/03/14 05:19:50 maxv Exp $ */
/*
* Copyright (c) 2008, 2010, 2016, 2017, 2019, 2020 The NetBSD Foundation, Inc.
@ -130,7 +130,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.363 2020/03/10 22:38:41 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.364 2020/03/14 05:19:50 maxv Exp $");
#include "opt_user_ldt.h"
#include "opt_lockdebug.h"
@ -4601,7 +4601,7 @@ pmap_get_physpage(void)
/*
* Expand the page tree with the specified amount of PTPs, mapping virtual
* addresses starting at kva. We populate all the levels but the last one
* (L1). The nodes of the tree are created as RWX, but the pages covered
* (L1). The nodes of the tree are created as RW, but the pages covered
* will be kentered in L1, with proper permissions.
*
* Used only by pmap_growkernel.
@ -4632,6 +4632,9 @@ pmap_alloc_level(struct pmap *cpm, vaddr_t kva, long *needed_ptps)
KASSERT(!pmap_valid_entry(pdep[i]));
pa = pmap_get_physpage();
pte = pmap_pa2pte(pa) | PTE_P | PTE_W;
#ifdef __x86_64__
pte |= pmap_pg_nx;
#endif
pmap_pte_set(&pdep[i], pte);
#ifdef XENPV