cifs: Fix busy dentry used after unmounting
Summary
| CVE | CVE-2026-64108 |
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| State | PUBLISHED |
|---|
| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-07-19 16:17:52 UTC |
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| Updated | 2026-07-19 16:17:52 UTC |
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| Description | In 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. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 708c276f516d27beaded7f372ac8111cee43926c c7364cea52531534676b9f7dbc0a477c11f4c050 git |
Not specified |
| CNA |
Linux |
Linux |
affected 0629a1a187e424373364d681b42b101894bdb548 bdc349a87f1fb02c18c4071858a06542bfea783d git |
Not specified |
| CNA |
Linux |
Linux |
affected 0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd f2deaa2f409a4598eaa10f2a93a676c0632af248 git |
Not specified |
| CNA |
Linux |
Linux |
affected f655467a9973f964b267871e5fef533ad5014494 5e7d9d0805e58fa3760894e73115b7a74024fd07 git |
Not specified |
| CNA |
Linux |
Linux |
affected 340cea84f691c5206561bb2e0147158fe02070be e1ffa6cf662383f95816eed1b623429d82675e75 git |
Not specified |
| CNA |
Linux |
Linux |
affected 340cea84f691c5206561bb2e0147158fe02070be c68337442f03953237a94577beb468ab2662a851 git |
Not specified |
| CNA |
Linux |
Linux |
affected 30afc6ea72cc6cf7c8d579e79b64232801c38d08 git |
Not specified |
| CNA |
Linux |
Linux |
affected 6.1.167 6.1.175 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 6.6.130 6.6.142 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 6.12.78 6.12.92 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 6.18.20 6.18.34 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 6.19.10 6.20 semver |
Not specified |
| CNA |
Linux |
Linux |
affected 7.0 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.0 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.1.175 6.1.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.6.142 6.6.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.92 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.34 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.0.11 7.0.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.1 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/c7364cea52531534676b9f7dbc0a477c11f4c050 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/bdc349a87f1fb02c18c4071858a06542bfea783d |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/e1ffa6cf662383f95816eed1b623429d82675e75 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/c68337442f03953237a94577beb468ab2662a851 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/5e7d9d0805e58fa3760894e73115b7a74024fd07 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/f2deaa2f409a4598eaa10f2a93a676c0632af248 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.
