File 6345603a-x86-P2M-refuse-new-alloc-for-dying.patch of Package xen.26659
# Commit ff600a8cf8e36f8ecbffecf96a035952e022ab87
# Date 2022-10-11 14:23:22 +0200
# Author Roger Pau Monné <roger.pau@citrix.com>
# Committer Jan Beulich <jbeulich@suse.com>
x86/p2m: refuse new allocations for dying domains
This will in particular prevent any attempts to add entries to the p2m,
once - in a subsequent change - non-root entries have been removed.
This is part of CVE-2022-33746 / XSA-410.
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tim Deegan <tim@xen.org>
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -244,6 +244,9 @@ static struct page_info *hap_alloc(struc
ASSERT(paging_locked_by_me(d));
+ if ( unlikely(d->is_dying) )
+ return NULL;
+
pg = page_list_remove_head(&d->arch.paging.hap.freelist);
if ( unlikely(!pg) )
return NULL;
@@ -280,7 +283,7 @@ static struct page_info *hap_alloc_p2m_p
d->arch.paging.hap.p2m_pages++;
ASSERT(!page_get_owner(pg) && !(pg->count_info & PGC_count_mask));
}
- else if ( !d->arch.paging.p2m_alloc_failed )
+ else if ( !d->arch.paging.p2m_alloc_failed && !d->is_dying )
{
d->arch.paging.p2m_alloc_failed = 1;
dprintk(XENLOG_ERR, "d%i failed to allocate from HAP pool\n",
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -938,6 +938,10 @@ static bool __must_check _shadow_preallo
if ( d->arch.paging.shadow.free_pages >= pages )
return true;
+ if ( unlikely(d->is_dying) )
+ /* No reclaim when the domain is dying, teardown will take care of it. */
+ return false;
+
/* Shouldn't have enabled shadows if we've no vcpus. */
ASSERT(d->vcpu && d->vcpu[0]);
@@ -988,7 +992,7 @@ static bool __must_check _shadow_preallo
d->arch.paging.shadow.free_pages,
d->arch.paging.shadow.p2m_pages);
- ASSERT(d->is_dying);
+ ASSERT_UNREACHABLE();
guest_flush_tlb_mask(d, d->dirty_cpumask);
@@ -1002,10 +1006,13 @@ static bool __must_check _shadow_preallo
* to avoid freeing shadows that the caller is currently working on. */
bool shadow_prealloc(struct domain *d, unsigned int type, unsigned int count)
{
- bool ret = _shadow_prealloc(d, shadow_size(type) * count);
+ bool ret;
+
+ if ( unlikely(d->is_dying) )
+ return false;
- if ( !ret && !d->is_dying &&
- (!d->is_shutting_down || d->shutdown_code != SHUTDOWN_crash) )
+ ret = _shadow_prealloc(d, shadow_size(type) * count);
+ if ( !ret && (!d->is_shutting_down || d->shutdown_code != SHUTDOWN_crash) )
/*
* Failing to allocate memory required for shadow usage can only result in
* a domain crash, do it here rather that relying on every caller to do it.
@@ -1231,6 +1238,9 @@ shadow_alloc_p2m_page(struct domain *d)
{
struct page_info *pg = NULL;
+ if ( unlikely(d->is_dying) )
+ return NULL;
+
/* This is called both from the p2m code (which never holds the
* paging lock) and the log-dirty code (which always does). */
paging_lock_recursive(d);