{"id":"CVE-2025-40006","url":"https://www.cyber-defence.io/tools/cve/CVE-2025-40006","generatedAt":"2026-10-28T03:42:12.208Z","title":"In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix folio is still mapped when deleted Migration may be raced with fallocating hole. remove_inode_single_folio will unmap the folio if the folio is still mapped.","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix folio is still mapped when deleted\n\nMigration may be raced with fallocating hole.  remove_inode_single_folio\nwill unmap the folio if the folio is still mapped.  However, it's called\nwithout folio lock.  If the folio is migrated and the mapped pte has been\nconverted to migration entry, folio_mapped() returns false, and won't\nunmap it.  Due to extra refcount held by remove_inode_single_folio,\nmigration fails, restores migration entry to normal pte, and the folio is\nmapped again.  As a result, we triggered BUG in filemap_unaccount_folio.\n\nThe log is as follows:\n BUG: Bad page cache in process hugetlb  pfn:156c00\n page: refcount:515 mapcount:0 mapping:0000000099fef6e1 index:0x0 pfn:0x156c00\n head: order:9 mapcount:1 entire_mapcount:1 nr_pages_mapped:0 pincount:0\n aops:hugetlbfs_aops ino:dcc dentry name(?):\"my_hugepage_file\"\n flags: 0x17ffffc00000c1(locked|waiters|head|node=0|zone=2|lastcpupid=0x1fffff)\n page_type: f4(hugetlb)\n page dumped because: still mapped when deleted\n CPU: 1 UID: 0 PID: 395 Comm: hugetlb Not tainted 6.17.0-rc5-00044-g7aac71907bde-dirty #484 NONE\n Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015\n Call Trace:\n  <TASK>\n  dump_stack_lvl+0x4f/0x70\n  filemap_unaccount_folio+0xc4/0x1c0\n  __filemap_remove_folio+0x38/0x1c0\n  filemap_remove_folio+0x41/0xd0\n  remove_inode_hugepages+0x142/0x250\n  hugetlbfs_fallocate+0x471/0x5a0\n  vfs_fallocate+0x149/0x380\n\nHold folio lock before checking if the folio is mapped to avold race with\nmigration.","published":"2025-10-20T16:15:37.000Z","lastModified":"2026-10-19T21:10:00.000Z","status":"Deferred","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"cwe":[],"affected":[],"epss":{"score":0.00202,"percentile":0.09999,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.20%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/21ee79ce938127f88fe07e409c1817f477dbe7ea","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3e851448078f5b01f6264915df3cfef75e323a12","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7b7387650dcf2881fd8bb55bcf3c8bd6c9542dd7","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/910d7749346c4b0acdc6e4adfdc4a9984281a206","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/91f548e920fbf8be3f285bfa3fa045ae017e836d","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bc1c9ce8aeff45318332035dbef9713fb9e982d7","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c1dc0524ab2cc3982d4e0d2bfac71a0cd4d65c39","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c9c2a51f91aea70e89b496cac360cd795a2b3c26","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-40006","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}