In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
arm64: make huge_ptep_get handled unaligned addresses<\/p>\n
huge_ptep_get() can be handed a virtual address pointing to the middle
\nof a contpmd\/contpte mapped hugetlb folio (examples of callers are
\npagemap_hugetlb_range, page_mapped_in_vma).<\/p>\n
The arm64 helper rewalks the pgtables in find_num_contig to answer
\nwhether the huge pte we have maps a contpmd or a contpte hugetlb folio,
\nand returns CONT_PMDS or CONT_PTES, so that it can collect a\/d bits over
\nthe contiguous ptes. We can falsely return CONT_PTES instead of
\nCONT_PMDS if the addr is not aligned. On systems where CONT_PTES !=
\nCONT_PMDS (meaning page size is 16K), we could collect excess A\/D bit
\nstate, meaning extra work for the kernel. Even worse, we may iterate
\nbeyond the PTE table and dereference a garbage ptep pointer to access
\nphysical memory we don’t own. Since the ptep pointer is a linear map
\naddress, we may run off the end of the linear map or into a hole,
\ndereference a VA not mapped into the kernel pgtables and cause kernel
\npanic.<\/p>\n
Fix this by aligning the pmdp pointer down to a contpmd base before
\nchecking equality with the passed huge pte pointer, to correctly answer
\nwhether the huge pte is the base of a contpmd block.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
arm64: make huge_ptep_get handled unaligned addresses<\/p>\n
huge_ptep_get() can be handed a virtual address pointing to the middle
\nof a <\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-5369","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/5369","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=5369"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5369"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5369"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}