CVE-2025-40006

mm/hugetlb: fix folio is still mapped when deleted

State: Published
Severity: 7.8 High
Published: Oct 20, 2025
Updated: Aug 5, 2026
Reserved: Apr 16, 2025

Description

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. However, it's called without folio lock. If the folio is migrated and the mapped pte has been converted to migration entry, folio_mapped() returns false, and won't unmap it. Due to extra refcount held by remove_inode_single_folio, migration fails, restores migration entry to normal pte, and the folio is mapped again. As a result, we triggered BUG in filemap_unaccount_folio.

The log is as follows: BUG: Bad page cache in process hugetlb pfn:156c00 page: refcount:515 mapcount:0 mapping:0000000099fef6e1 index:0x0 pfn:0x156c00 head: order:9 mapcount:1 entire_mapcount:1 nr_pages_mapped:0 pincount:0 aops:hugetlbfs_aops ino:dcc dentry name(?):"my_hugepage_file" flags: 0x17ffffc00000c1(locked|waiters|head|node=0|zone=2|lastcpupid=0x1fffff) page_type: f4(hugetlb) page dumped because: still mapped when deleted CPU: 1 UID: 0 PID: 395 Comm: hugetlb Not tainted 6.17.0-rc5-00044-g7aac71907bde-dirty #484 NONE Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 Call Trace: <TASK> dump_stack_lvl+0x4f/0x70 filemap_unaccount_folio+0xc4/0x1c0 __filemap_remove_folio+0x38/0x1c0 filemap_remove_folio+0x41/0xd0 remove_inode_hugepages+0x142/0x250 hugetlbfs_fallocate+0x471/0x5a0 vfs_fallocate+0x149/0x380

Hold folio lock before checking if the folio is mapped to avold race with migration.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	4aae8d1c051ea00b456da6811bc36d1f69de5445 to before bc1c9ce8aeff45318332035dbef9713fb9e982d7Affected 4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 91f548e920fbf8be3f285bfa3fa045ae017e836dAffected 4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 3e851448078f5b01f6264915df3cfef75e323a12Affected 4aae8d1c051ea00b456da6811bc36d1f69de5445 to before c1dc0524ab2cc3982d4e0d2bfac71a0cd4d65c39Affected 4aae8d1c051ea00b456da6811bc36d1f69de5445 to before c9c2a51f91aea70e89b496cac360cd795a2b3c26Affected 4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 910d7749346c4b0acdc6e4adfdc4a9984281a206Affected 4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 21ee79ce938127f88fe07e409c1817f477dbe7eaAffected 4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 7b7387650dcf2881fd8bb55bcf3c8bd6c9542dd7Affected
LinuxLinux	4.5Affected before 4.5Not affected 5.4.300 through 5.4.Not affected 5.10.245 through 5.10.Not affected 5.15.194 through 5.15.Not affected 6.1.155 through 6.1.Not affected 6.6.109 through 6.6.Not affected 6.12.50 through 6.12.Not affected 6.16.10 through 6.16.*Not affected 6.17 and laterNot affected

Product

Versions

LinuxLinux

4aae8d1c051ea00b456da6811bc36d1f69de5445 to before bc1c9ce8aeff45318332035dbef9713fb9e982d7Affected
4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 91f548e920fbf8be3f285bfa3fa045ae017e836dAffected
4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 3e851448078f5b01f6264915df3cfef75e323a12Affected
4aae8d1c051ea00b456da6811bc36d1f69de5445 to before c1dc0524ab2cc3982d4e0d2bfac71a0cd4d65c39Affected
4aae8d1c051ea00b456da6811bc36d1f69de5445 to before c9c2a51f91aea70e89b496cac360cd795a2b3c26Affected
4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 910d7749346c4b0acdc6e4adfdc4a9984281a206Affected
4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 21ee79ce938127f88fe07e409c1817f477dbe7eaAffected
4aae8d1c051ea00b456da6811bc36d1f69de5445 to before 7b7387650dcf2881fd8bb55bcf3c8bd6c9542dd7Affected

LinuxLinux

4.5Affected
before 4.5Not affected
5.4.300 through 5.4.*Not affected
5.10.245 through 5.10.*Not affected
5.15.194 through 5.15.*Not affected
6.1.155 through 6.1.*Not affected
6.6.109 through 6.6.*Not affected
6.12.50 through 6.12.*Not affected
6.16.10 through 6.16.*Not affected
6.17 and laterNot affected

References

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