In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
mm\/page_vma_mapped: fix device-private PMD handling<\/p>\n
Commit 65edfda6f3f2 (“mm\/rmap: extend rmap and migration support
\ndevice-private entries”) introduced the concept of device-private PMD
\nentries, but did not correctly update the rmap walk code to account for
\nthem.<\/p>\n
As a result, when page_vma_mapped_walk() encounters device-private PMD
\nentries, it takes no action other than to acquire the PMD lock and exit.<\/p>\n
However this is highly problematic for two reasons – firstly, device
\nprivate entries possess a PFN so check_pmd() needs to be called to ensure
\nan overlapping PFN range.<\/p>\n
Secondly, and more importantly, if PVMW_MIGRATION is set the caller
\nassumes the returned entry is a migration entry, resulting in memory
\ncorruption when the caller tries to interpret the device private entry as
\nsuch.<\/p>\n
In addition, commit 146287290023 (“mm\/huge_memory: implement
\ndevice-private THP splitting”) allowed device private PMDs to be split
\nlike THP mappings, but again did not update this code path.<\/p>\n
As a result, we might race a PMD split prior to acquiring the PMD lock.<\/p>\n
This patch addresses all of these issues by invoking check_pmd(), ensuring
\nPMVW_MIGRATION is not set and checks whether a split raced us we do for
\nPMD THP and migration entries.<\/p>\n
Instead of checking for a subset of the cases after taking the pmd_lock(),
\nput device-private along with pmd_trans_huge() and
\npmd_is_migration_entry(). Also remove thp_migration_supported() as it is
\nalready guarded by pmd_is_migration_entry().<\/p>\n
[akpm@linux-foundation.org: fix Raspberry Pi 1 build, per David]<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
mm\/page_vma_mapped: fix device-private PMD handling<\/p>\n
Commit 65edfda6f3f2 (“mm\/rmap: extend rmap and migration support
\ndevice-privat<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-5367","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/5367","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=5367"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5367"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5367"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}