In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
futex: Fix private hash use-after-free on resize<\/p>\n
poll_state_synchronize_rcu(mm->futex.phash.batches) is used by
\nfutex_ref_drop() to check that a grace period has passed since the
\ncurrent hash was published. This relies on batches referencing a grace
\nperiod which started after the hash pointer was assigned.<\/p>\n
__futex_pivot_hash() sets mmph->batches before it replaces mmph->hash:<\/p>\n
scoped_guard(rcu) {
\n mmph->batches = get_state_synchronize_rcu();
\n rcu_assign_pointer(mmph->hash, new);
\n }<\/p>\n
The scoped_guard(rcu) doesn’t stop new grace periods from starting, and
\nif one starts between those two assignments, futex_ref_drop() can move
\nforward while a reader still holds a pointer to the old hash.<\/p>\n
Fix things by setting mmph->batches after assigning mmph->hash. The
\nscoped_guard(rcu) isn’t needed, so let’s drop that as well.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
futex: Fix private hash use-after-free on resize<\/p>\n
poll_state_synchronize_rcu(mm->futex.phash.batches) is used by
\nfutex_ref_drop() t<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-41260","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/41260","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=41260"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=41260"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=41260"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}