GHSA-3MRW-XF65-FQJH
Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:32In the Linux kernel, the following vulnerability has been resolved:
cifs: Fix busy dentry used after unmounting
Since commit 340cea84f691c ("cifs: open files should not hold ref on superblock"), cifs file only holds the dentry ref_cnt, the cifs file close work(cfile->deferred) could be executed after unmounting, which will trigger a warning in generic_shutdown_super: BUG: Dentry 00000000a14a6845{i=c,n=file} still in use (1) [unmount of cifs cifs]
The detailed processs is: process A process B kworker fd = open(PATH) vfs_open file->__f_path = *path // dentry->d_lockref.count = 1 cifs_open cifs_new_fileinfo cfile->dentry = dget(dentry) // dentry->d_lockref.count = 2 close(fd) __fput cifs_close queue_delayed_work(deferredclose_wq, cfile->deferred) dput(dentry) // dentry->d_lockref.count = 1 smb2_deferred_work_close _cifsFileInfo_put list_del(&cifs_file->flist) umount cleanup_mnt deactivate_super cifs_kill_sb cifs_close_all_deferred_files_sb cifs_close_all_deferred_files // cannot find cfile, skip _cifsFileInfo_put kill_anon_super generic_shutdown_super shrink_dcache_for_umount umount_check WARN ! // dentry->d_lockref.count = 1 cifsFileInfo_put_final dput(cifs_file->dentry) // dentry->d_lockref.count = 0
Fix it by flushing 'deferredclose_wq' before calling kill_anon_super.
Fetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548.
{
"affected": [],
"aliases": [
"CVE-2026-64108"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-07-19T16:17:52Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: Fix busy dentry used after unmounting\n\nSince commit 340cea84f691c (\"cifs: open files should not hold ref on\nsuperblock\"), cifs file only holds the dentry ref_cnt, the cifs file\nclose work(cfile-\u003edeferred) could be executed after unmounting, which\nwill trigger a warning in generic_shutdown_super:\n BUG: Dentry 00000000a14a6845{i=c,n=file} still in use (1) [unmount of\n cifs cifs]\n\nThe detailed processs is:\n process A process B kworker\n fd = open(PATH)\n vfs_open\n file-\u003e__f_path = *path // dentry-\u003ed_lockref.count = 1\n cifs_open\n cifs_new_fileinfo\n cfile-\u003edentry = dget(dentry) // dentry-\u003ed_lockref.count = 2\n close(fd)\n __fput\n cifs_close\n queue_delayed_work(deferredclose_wq, cfile-\u003edeferred)\n dput(dentry) // dentry-\u003ed_lockref.count = 1\n\t\t\t smb2_deferred_work_close\n\t\t\t\t\t _cifsFileInfo_put\n\t\t\t\t\t list_del(\u0026cifs_file-\u003eflist)\n umount\n\t\t cleanup_mnt\n\t\t deactivate_super\n\t\t cifs_kill_sb\n\t\t cifs_close_all_deferred_files_sb\n\t\t\t cifs_close_all_deferred_files\n\t\t\t // cannot find cfile, skip _cifsFileInfo_put\n\t\t\tkill_anon_super\n\t\t\t generic_shutdown_super\n\t\t\t shrink_dcache_for_umount\n\t\t\t umount_check\n\t\t\t WARN ! // dentry-\u003ed_lockref.count = 1\n\t\t\t\t\t cifsFileInfo_put_final\n\t\t\t\t\t dput(cifs_file-\u003edentry)\n\t\t // dentry-\u003ed_lockref.count = 0\n\nFix it by flushing \u0027deferredclose_wq\u0027 before calling kill_anon_super.\n\nFetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548.",
"id": "GHSA-3mrw-xf65-fqjh",
"modified": "2026-07-20T15:32:00Z",
"published": "2026-07-19T18:31:52Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64108"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5e7d9d0805e58fa3760894e73115b7a74024fd07"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bdc349a87f1fb02c18c4071858a06542bfea783d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c68337442f03953237a94577beb468ab2662a851"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c7364cea52531534676b9f7dbc0a477c11f4c050"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e1ffa6cf662383f95816eed1b623429d82675e75"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f2deaa2f409a4598eaa10f2a93a676c0632af248"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.