{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40006", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.151Z", "datePublished": "2025-10-20T15:26:53.097Z", "dateUpdated": "2026-08-05T12:07:03.344Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:07:03.344Z" }, "descriptions": [ { "lang": "en", "value": "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 \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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Exploitation requires local syscalls only — `memfd_create(MFD_HUGETLB)`/`mmap` plus `fallocate(FALLOC_FL_PUNCH_HOLE)` racing against `mbind`/`move_pages`. There is no network-reachable path into hugetlbfs fallocate.\nAC:L - The attacker controls both sides of the race with its own threads — one looping on punch-hole, the other looping on NUMA migration of the same mapping — and can retry indefinitely at no cost until the window is hit. Per race-condition guidance, attacker-driven races are Low.\nPR:L - `memfd_create(MFD_HUGETLB)` uses HUGETLB_ANONHUGE_INODE and bypasses the `can_do_hugetlb_shm()`/CAP_IPC_LOCK check entirely, and `MPOL_MF_MOVE` on one's own address space needs no capability, so an ordinary unprivileged local user can reach the whole path.\nUI:N - The attacking process performs every step itself; no victim action, mount, or file open by another user is needed.\nS:U - The vulnerable code and the corrupted resources are both in the host kernel's memory management, so the impact stays within a single security authority despite the severity.\nC:H - The huge page is unlinked from the page cache with its `mapping` cleared while the attacker retains writable PTEs, and hugetlb folios are explicitly excluded from `filemap_unaccount_folio()`'s recovery heuristic — leaving a stale mapping to a 2MB page the kernel may recycle to another process, container, or hugepage-backed KVM guest, yielding arbitrary read of that memory.\nI:H - The same stale writable mapping gives an arbitrary-write primitive over whatever the kernel later places in that recycled huge page, and the hugetlb reserve/subpool counters are decremented for a page still in use, corrupting pool accounting — memory corruption of this class is leveragable for control-flow hijack.\nA:H - The bug's directly observed symptom is the `BUG: Bad page cache ... still mapped when deleted` report, which is a hard `VM_BUG_ON_FOLIO()` panic under CONFIG_DEBUG_VM and a `TAINT_BAD_PAGE` plus unrecoverable page-cache/hugetlb-pool corruption otherwise, repeatable at will by an unprivileged user." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/hugetlbfs/inode.c" ], "versions": [ { "version": "4aae8d1c051ea00b456da6811bc36d1f69de5445", "lessThan": "bc1c9ce8aeff45318332035dbef9713fb9e982d7", "status": "affected", "versionType": "git" }, { "version": "4aae8d1c051ea00b456da6811bc36d1f69de5445", "lessThan": "91f548e920fbf8be3f285bfa3fa045ae017e836d", "status": "affected", "versionType": "git" }, { "version": "4aae8d1c051ea00b456da6811bc36d1f69de5445", "lessThan": "3e851448078f5b01f6264915df3cfef75e323a12", "status": "affected", "versionType": "git" }, { "version": "4aae8d1c051ea00b456da6811bc36d1f69de5445", "lessThan": "c1dc0524ab2cc3982d4e0d2bfac71a0cd4d65c39", "status": "affected", "versionType": "git" }, { "version": "4aae8d1c051ea00b456da6811bc36d1f69de5445", "lessThan": "c9c2a51f91aea70e89b496cac360cd795a2b3c26", "status": "affected", "versionType": "git" }, { "version": "4aae8d1c051ea00b456da6811bc36d1f69de5445", "lessThan": "910d7749346c4b0acdc6e4adfdc4a9984281a206", "status": "affected", "versionType": "git" }, { "version": "4aae8d1c051ea00b456da6811bc36d1f69de5445", "lessThan": "21ee79ce938127f88fe07e409c1817f477dbe7ea", "status": "affected", "versionType": "git" }, { "version": "4aae8d1c051ea00b456da6811bc36d1f69de5445", "lessThan": "7b7387650dcf2881fd8bb55bcf3c8bd6c9542dd7", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/hugetlbfs/inode.c" ], "versions": [ { "version": "4.5", "status": "affected" }, { "version": "0", "lessThan": "4.5", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.300", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.245", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.194", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.155", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.109", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.50", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.10", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "5.4.300" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "5.10.245" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "5.15.194" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "6.1.155" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "6.6.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "6.12.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "6.16.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/bc1c9ce8aeff45318332035dbef9713fb9e982d7" }, { "url": "https://git.kernel.org/stable/c/91f548e920fbf8be3f285bfa3fa045ae017e836d" }, { "url": "https://git.kernel.org/stable/c/3e851448078f5b01f6264915df3cfef75e323a12" }, { "url": "https://git.kernel.org/stable/c/c1dc0524ab2cc3982d4e0d2bfac71a0cd4d65c39" }, { "url": "https://git.kernel.org/stable/c/c9c2a51f91aea70e89b496cac360cd795a2b3c26" }, { "url": "https://git.kernel.org/stable/c/910d7749346c4b0acdc6e4adfdc4a9984281a206" }, { "url": "https://git.kernel.org/stable/c/21ee79ce938127f88fe07e409c1817f477dbe7ea" }, { "url": "https://git.kernel.org/stable/c/7b7387650dcf2881fd8bb55bcf3c8bd6c9542dd7" } ], "title": "mm/hugetlb: fix folio is still mapped when deleted", "x_generator": { "engine": "bippy-1.2.0" } } } }