34 lines
1.2 KiB
Diff
34 lines
1.2 KiB
Diff
# Commit 5540b94e8191059eb9cbbe98ac316232a42208f6
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# Date 2024-06-13 16:53:34 +0200
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# Author Jan Beulich <jbeulich@suse.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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x86/EPT: correct special page checking in epte_get_entry_emt()
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mfn_valid() granularity is (currently) 256Mb. Therefore the start of a
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1Gb page passing the test doesn't necessarily mean all parts of such a
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range would also pass. Yet using the result of mfn_to_page() on an MFN
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which doesn't pass mfn_valid() checking is liable to result in a crash
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(the invocation of mfn_to_page() alone is presumably "just" UB in such a
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case).
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Fixes: ca24b2ffdbd9 ("x86/hvm: set 'ipat' in EPT for special pages")
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
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--- a/xen/arch/x86/mm/p2m-ept.c
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+++ b/xen/arch/x86/mm/p2m-ept.c
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@@ -518,8 +518,12 @@ int epte_get_entry_emt(struct domain *d,
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}
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for ( special_pgs = i = 0; i < (1ul << order); i++ )
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- if ( is_special_page(mfn_to_page(mfn_add(mfn, i))) )
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+ {
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+ mfn_t cur = mfn_add(mfn, i);
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+
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+ if ( mfn_valid(cur) && is_special_page(mfn_to_page(cur)) )
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special_pgs++;
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+ }
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if ( special_pgs )
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{
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