[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen stable-4.14] xen/arm: p2m: Always clear the P2M entry when the mapping is removed
commit 861e27398c1da53e1c483c5dde12ad019ced6786 Author: Julien Grall <jgrall@xxxxxxxxxx> AuthorDate: Tue Jan 25 13:49:06 2022 +0100 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Tue Jan 25 13:49:06 2022 +0100 xen/arm: p2m: Always clear the P2M entry when the mapping is removed Commit 2148a125b73b ("xen/arm: Track page accessed between batch of Set/Way operations") allowed an entry to be invalid from the CPU PoV (lpae_is_valid()) but valid for Xen (p2m_is_valid()). This is useful to track which page is accessed and only perform an action on them (e.g. clean & invalidate the cache after a set/way instruction). Unfortunately, __p2m_set_entry() is only zeroing the P2M entry when lpae_is_valid() returns true. This means the entry will not be zeroed if the entry was valid from Xen PoV but invalid from the CPU PoV for tracking purpose. As a consequence, this will allow a domain to continue to access the page after it was removed. Resolve the issue by always zeroing the entry if it the LPAE bit is set or the entry is about to be removed. This is CVE-2022-23033 / XSA-393. Reported-by: Dmytro Firsov <Dmytro_Firsov@xxxxxxxx> Fixes: 2148a125b73b ("xen/arm: Track page accessed between batch of Set/Way operations") Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx> master commit: a428b913a002eb2b7425b48029c20a52eeee1b5a master date: 2022-01-25 13:25:01 +0100 --- xen/arch/arm/p2m.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c index ac821a9094..2290b7114f 100644 --- a/xen/arch/arm/p2m.c +++ b/xen/arch/arm/p2m.c @@ -1008,7 +1008,7 @@ static int __p2m_set_entry(struct p2m_domain *p2m, * sequence when updating the translation table (D4.7.1 in ARM DDI * 0487A.j). */ - if ( lpae_is_valid(orig_pte) ) + if ( lpae_is_valid(orig_pte) || removing_mapping ) p2m_remove_pte(entry, p2m->clean_pte); if ( removing_mapping ) -- generated by git-patchbot for /home/xen/git/xen.git#stable-4.14
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