In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
s390\/mm: Fix handling of _PAGE_UNUSED pte bit<\/p>\n
The _PAGE_UNUSED softbit should not really be lying around. Its sole
\npurpose is to signal to try_to_unmap_one() and try_to_migrate_one()
\nthat the page can be discarded instead of being moved \/ swapped.<\/p>\n
KVM has no way to know why a page is being unmapped, so it sets the bit
\non userspace ptes corresponding to unused guest pages every time they
\nget unmapped. KVM has no reasonable way to clear the bit once the page
\nis in use again.<\/p>\n
While set_ptes() checks and clears the bit, other paths that set new
\nptes did not. This led to used pages being thrown out as if they were
\nunused, causing guest corruption.<\/p>\n
Fix the issue by clearing the _PAGE_UNUSED bit for present ptes in
\nset_pte(), i.e. whenever a present pte is getting set. The check in
\nset_ptes() is then redundant and can be removed.<\/p>\n
Also fix gmap_helper_try_set_pte_unused() to only set the bit if the
\npte is present; the _PAGE_UNUSED bit is only defined for present ptes
\nand thus should not be set for non-present ptes.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
s390\/mm: Fix handling of _PAGE_UNUSED pte bit<\/p>\n
The _PAGE_UNUSED softbit should not really be lying around. Its sole
\npurpose is to s<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-7063","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/7063","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7063"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7063"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7063"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}