GHSA-9GHH-P583-M6M8
Vulnerability from github – Published: 2026-03-25 12:30 – Updated: 2026-04-24 18:30In the Linux kernel, the following vulnerability has been resolved:
mm: thp: deny THP for files on anonymous inodes
file_thp_enabled() incorrectly allows THP for files on anonymous inodes (e.g. guest_memfd and secretmem). These files are created via alloc_file_pseudo(), which does not call get_write_access() and leaves inode->i_writecount at 0. Combined with S_ISREG(inode->i_mode) being true, they appear as read-only regular files when CONFIG_READ_ONLY_THP_FOR_FS is enabled, making them eligible for THP collapse.
Anonymous inodes can never pass the inode_is_open_for_write() check since their i_writecount is never incremented through the normal VFS open path. The right thing to do is to exclude them from THP eligibility altogether, since CONFIG_READ_ONLY_THP_FOR_FS was designed for real filesystem files (e.g. shared libraries), not for pseudo-filesystem inodes.
For guest_memfd, this allows khugepaged and MADV_COLLAPSE to create large folios in the page cache via the collapse path, but the guest_memfd fault handler does not support large folios. This triggers WARN_ON_ONCE(folio_test_large(folio)) in kvm_gmem_fault_user_mapping().
For secretmem, collapse_file() tries to copy page contents through the direct map, but secretmem pages are removed from the direct map. This can result in a kernel crash:
BUG: unable to handle page fault for address: ffff88810284d000
RIP: 0010:memcpy_orig+0x16/0x130
Call Trace:
collapse_file
hpage_collapse_scan_file
madvise_collapse
Secretmem is not affected by the crash on upstream as the memory failure recovery handles the failed copy gracefully, but it still triggers confusing false memory failure reports:
Memory failure: 0x106d96f: recovery action for clean unevictable
LRU page: Recovered
Check IS_ANON_FILE(inode) in file_thp_enabled() to deny THP for all anonymous inode files.
{
"affected": [],
"aliases": [
"CVE-2026-23375"
],
"database_specific": {
"cwe_ids": [
"CWE-617"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-25T11:16:37Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: thp: deny THP for files on anonymous inodes\n\nfile_thp_enabled() incorrectly allows THP for files on anonymous inodes\n(e.g. guest_memfd and secretmem). These files are created via\nalloc_file_pseudo(), which does not call get_write_access() and leaves\ninode-\u003ei_writecount at 0. Combined with S_ISREG(inode-\u003ei_mode) being\ntrue, they appear as read-only regular files when\nCONFIG_READ_ONLY_THP_FOR_FS is enabled, making them eligible for THP\ncollapse.\n\nAnonymous inodes can never pass the inode_is_open_for_write() check\nsince their i_writecount is never incremented through the normal VFS\nopen path. The right thing to do is to exclude them from THP eligibility\naltogether, since CONFIG_READ_ONLY_THP_FOR_FS was designed for real\nfilesystem files (e.g. shared libraries), not for pseudo-filesystem\ninodes.\n\nFor guest_memfd, this allows khugepaged and MADV_COLLAPSE to create\nlarge folios in the page cache via the collapse path, but the\nguest_memfd fault handler does not support large folios. This triggers\nWARN_ON_ONCE(folio_test_large(folio)) in kvm_gmem_fault_user_mapping().\n\nFor secretmem, collapse_file() tries to copy page contents through the\ndirect map, but secretmem pages are removed from the direct map. This\ncan result in a kernel crash:\n\n BUG: unable to handle page fault for address: ffff88810284d000\n RIP: 0010:memcpy_orig+0x16/0x130\n Call Trace:\n collapse_file\n hpage_collapse_scan_file\n madvise_collapse\n\nSecretmem is not affected by the crash on upstream as the memory failure\nrecovery handles the failed copy gracefully, but it still triggers\nconfusing false memory failure reports:\n\n Memory failure: 0x106d96f: recovery action for clean unevictable\n LRU page: Recovered\n\nCheck IS_ANON_FILE(inode) in file_thp_enabled() to deny THP for all\nanonymous inode files.",
"id": "GHSA-9ghh-p583-m6m8",
"modified": "2026-04-24T18:30:41Z",
"published": "2026-03-25T12:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23375"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0524ee56af2c9bfbad152a810f1ca95de8ca00d7"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/08de46a75f91a6661bc1ce0a93614f4bc313c581"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dd085fe9a8ebfc5d10314c60452db38d2b75e609"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f6fa05f0dddd387417d0c28281ddb951582514d6"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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