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From 3422c19d85a3d23a9d798eafb739ffb8865522d2 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Tue, 11 Oct 2022 14:52:59 +0200
Subject: [PATCH 05/26] x86/HAP: adjust monitor table related error handling
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
hap_make_monitor_table() will return INVALID_MFN if it encounters an
error condition, but hap_update_paging_modes() wasn’t handling this
value, resulting in an inappropriate value being stored in
monitor_table. This would subsequently misguide at least
hap_vcpu_teardown(). Avoid this by bailing early.
Further, when a domain has/was already crashed or (perhaps less
important as there's no such path known to lead here) is already dying,
avoid calling domain_crash() on it again - that's at best confusing.
This is part of CVE-2022-33746 / XSA-410.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
master commit: 5b44a61180f4f2e4f490a28400c884dd357ff45d
master date: 2022-10-11 14:21:56 +0200
---
xen/arch/x86/mm/hap/hap.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index a8f5a19da917..d75dc2b9ed3d 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -39,6 +39,7 @@
#include <asm/domain.h>
#include <xen/numa.h>
#include <asm/hvm/nestedhvm.h>
+#include <public/sched.h>
#include "private.h"
@@ -405,8 +406,13 @@ static mfn_t hap_make_monitor_table(struct vcpu *v)
return m4mfn;
oom:
- printk(XENLOG_G_ERR "out of memory building monitor pagetable\n");
- domain_crash(d);
+ if ( !d->is_dying &&
+ (!d->is_shutting_down || d->shutdown_code != SHUTDOWN_crash) )
+ {
+ printk(XENLOG_G_ERR "%pd: out of memory building monitor pagetable\n",
+ d);
+ domain_crash(d);
+ }
return INVALID_MFN;
}
@@ -766,6 +772,9 @@ static void hap_update_paging_modes(struct vcpu *v)
if ( pagetable_is_null(v->arch.hvm.monitor_table) )
{
mfn_t mmfn = hap_make_monitor_table(v);
+
+ if ( mfn_eq(mmfn, INVALID_MFN) )
+ goto unlock;
v->arch.hvm.monitor_table = pagetable_from_mfn(mmfn);
make_cr3(v, mmfn);
hvm_update_host_cr3(v);
@@ -774,6 +783,7 @@ static void hap_update_paging_modes(struct vcpu *v)
/* CR3 is effectively updated by a mode change. Flush ASIDs, etc. */
hap_update_cr3(v, 0, false);
+ unlock:
paging_unlock(d);
put_gfn(d, cr3_gfn);
}
--
2.37.3
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