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commit 042a5b7024e7b27f5806914b9d42099a48c8f893
Author: Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Thu Oct 20 12:14:30 2022 +0100
Commit: Stefano Stabellini <stefano.stabellini@amd.com>
CommitDate: Tue Dec 6 17:00:00 2022 -0800

xen/arm: Correct the p2m pool size calculations

Allocating or freeing p2m pages doesn't alter the size of the mempool; only
the split between free and used pages.

Right now, the hypercalls operate on the free subset of the pool, meaning that
XEN_DOMCTL_get_paging_mempool_size varies with time as the guest shuffles its
physmap, and XEN_DOMCTL_set_paging_mempool_size ignores the used subset of the
pool and lets the guest grow unbounded.

This fixes test-pagign-mempool on ARM so that the behaviour matches x86.

This is part of XSA-409 / CVE-2022-33747.

Fixes: cbea5a1149ca ("xen/arm: Allocate and free P2M pages from the P2M pool")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Release-acked-by: Henry Wang <Henry.Wang@arm.com>
---
xen/arch/arm/p2m.c | 4 ----
1 file changed, 4 deletions(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 6f87e17c1d..eba443ab23 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -78,7 +78,6 @@ static struct page_info *p2m_alloc_page(struct domain *d)
spin_unlock(&d->arch.paging.lock);
return NULL;
}
- d->arch.paging.p2m_total_pages--;
}
spin_unlock(&d->arch.paging.lock);

@@ -91,10 +90,7 @@ static void p2m_free_page(struct domain *d, struct page_info *pg)
if ( is_hardware_domain(d) )
free_domheap_page(pg);
else
- {
- d->arch.paging.p2m_total_pages++;
page_list_add_tail(pg, &d->arch.paging.p2m_freelist);
- }
spin_unlock(&d->arch.paging.lock);
}

--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.16