{"id":"DEBIAN-CVE-2022-49778","details":"In the Linux kernel, the following vulnerability has been resolved:  arm64/mm: fix incorrect file_map_count for non-leaf pmd/pud  The page table check trigger BUG_ON() unexpectedly when collapse hugepage:   ------------[ cut here ]------------  kernel BUG at mm/page_table_check.c:82!  Internal error: Oops - BUG: 00000000f2000800 [#1] SMP  Dumping ftrace buffer:     (ftrace buffer empty)  Modules linked in:  CPU: 6 PID: 68 Comm: khugepaged Not tainted 6.1.0-rc3+ #750  Hardware name: linux,dummy-virt (DT)  pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)  pc : page_table_check_clear.isra.0+0x258/0x3f0  lr : page_table_check_clear.isra.0+0x240/0x3f0 [...]  Call trace:   page_table_check_clear.isra.0+0x258/0x3f0   __page_table_check_pmd_clear+0xbc/0x108   pmdp_collapse_flush+0xb0/0x160   collapse_huge_page+0xa08/0x1080   hpage_collapse_scan_pmd+0xf30/0x1590   khugepaged_scan_mm_slot.constprop.0+0x52c/0xac8   khugepaged+0x338/0x518   kthread+0x278/0x2f8   ret_from_fork+0x10/0x20 [...]  Since pmd_user_accessible_page() doesn't check if a pmd is leaf, it decrease file_map_count for a non-leaf pmd comes from collapse_huge_page(). and so trigger BUG_ON() unexpectedly.  Fix this problem by using pmd_leaf() insteal of pmd_present() in pmd_user_accessible_page(). Moreover, use pud_leaf() for pud_user_accessible_page() too.","modified":"2026-08-27T23:04:47.048300526Z","published":"2025-05-01T15:16:00.980Z","upstream":["CVE-2022-49778"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2022-49778"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49778.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49778.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.0.10-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2022-49778.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}