diff options
Diffstat (limited to 'sysutils/xenkernel41/patches/patch-XSA-182')
| -rw-r--r-- | sysutils/xenkernel41/patches/patch-XSA-182 | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/sysutils/xenkernel41/patches/patch-XSA-182 b/sysutils/xenkernel41/patches/patch-XSA-182 new file mode 100644 index 00000000000..964641e2be4 --- /dev/null +++ b/sysutils/xenkernel41/patches/patch-XSA-182 @@ -0,0 +1,90 @@ +$NetBSD: patch-XSA-182,v 1.1.2.2 2016/07/28 14:09:15 spz Exp $ + +backported from: + +From 798c1498f764bfaa7b0b955bab40b01b0610d372 Mon Sep 17 00:00:00 2001 +From: Andrew Cooper <andrew.cooper3@citrix.com> +Date: Mon, 11 Jul 2016 14:32:03 +0100 +Subject: [PATCH] x86/pv: Remove unsafe bits from the mod_l?_entry() fastpath + +All changes in writeability and cacheability must go through full +re-validation. + +Rework the logic as a whitelist, to make it clearer to follow. + +This is XSA-182 + +--- xen/arch/x86/mm.c.orig 2016-07-26 16:51:13.000000000 +0200 ++++ xen/arch/x86/mm.c 2016-07-26 16:53:07.000000000 +0200 +@@ -1792,6 +1792,14 @@ + _t ## e_get_intpte(_o), _t ## e_get_intpte(_n), \ + (_m), (_v), (_ad)) + ++/* ++ * PTE flags that a guest may change without re-validating the PTE. ++ * All other bits affect translation, caching, or Xen's safety. ++ */ ++#define FASTPATH_FLAG_WHITELIST \ ++ (_PAGE_NX_BIT | _PAGE_AVAIL_HIGH | _PAGE_AVAIL | _PAGE_GLOBAL | \ ++ _PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_USER) ++ + /* Update the L1 entry at pl1e to new value nl1e. */ + static int mod_l1_entry(l1_pgentry_t *pl1e, l1_pgentry_t nl1e, + unsigned long gl1mfn, int preserve_ad, +@@ -1829,8 +1837,8 @@ + return 0; + } + +- /* Fast path for identical mapping, r/w and presence. */ +- if ( !l1e_has_changed(ol1e, nl1e, _PAGE_RW | _PAGE_PRESENT) ) ++ /* Fast path for sufficiently-similar mappings.*/ ++ if ( !l1e_has_changed(ol1e, nl1e, ~FASTPATH_FLAG_WHITELIST) ) + { + adjust_guest_l1e(nl1e, pt_dom); + rc = UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu, +@@ -1897,11 +1905,8 @@ + return 0; + } + +- /* Fast path for identical mapping and presence. */ +- if ( !l2e_has_changed(ol2e, nl2e, +- unlikely(opt_allow_superpage) +- ? _PAGE_PSE | _PAGE_RW | _PAGE_PRESENT +- : _PAGE_PRESENT) ) ++ /* Fast path for sufficiently-similar mappings. */ ++ if ( !l2e_has_changed(ol2e, nl2e, ~FASTPATH_FLAG_WHITELIST) ) + { + adjust_guest_l2e(nl2e, d); + rc = UPDATE_ENTRY(l2, pl2e, ol2e, nl2e, pfn, vcpu, preserve_ad); +@@ -1965,8 +1970,8 @@ + return -EINVAL; + } + +- /* Fast path for identical mapping and presence. */ +- if ( !l3e_has_changed(ol3e, nl3e, _PAGE_PRESENT) ) ++ /* Fast path for sufficiently-similar mappings. */ ++ if ( !l3e_has_changed(ol3e, nl3e, ~FASTPATH_FLAG_WHITELIST) ) + { + adjust_guest_l3e(nl3e, d); + rc = UPDATE_ENTRY(l3, pl3e, ol3e, nl3e, pfn, vcpu, preserve_ad); +@@ -2035,8 +2040,8 @@ + return -EINVAL; + } + +- /* Fast path for identical mapping and presence. */ +- if ( !l4e_has_changed(ol4e, nl4e, _PAGE_PRESENT) ) ++ /* Fast path for sufficiently-similar mappings. */ ++ if ( !l4e_has_changed(ol4e, nl4e, ~FASTPATH_FLAG_WHITELIST) ) + { + adjust_guest_l4e(nl4e, d); + rc = UPDATE_ENTRY(l4, pl4e, ol4e, nl4e, pfn, vcpu, preserve_ad); +--- xen/include/asm-x86/page.h.orig 2014-09-02 08:22:57.000000000 +0200 ++++ xen/include/asm-x86/page.h 2016-07-26 16:39:51.000000000 +0200 +@@ -332,6 +332,7 @@ + #define _PAGE_AVAIL2 0x800U + #define _PAGE_AVAIL 0xE00U + #define _PAGE_PSE_PAT 0x1000U ++#define _PAGE_AVAIL_HIGH (0x7ffU << 12) + #define _PAGE_PAGED 0x2000U + #define _PAGE_SHARED 0x4000U + |