CVE-2026-72315
smb: client: fix busy dentry warning on unmount after DIO
Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix busy dentry warning on unmount after DIO Commit c68337442f03 ("cifs: Fix busy dentry used after unmounting") fixed the issue in cifs where deferred close of a file led to a dentry reference count not being released in umount, by flushing deferredclose_wq in cifs_kill_sb() to solve it. However, the cifs DIO path suffers from the same busy-dentry problem caused by a delayed dentry reference-count release: [dio] [cifsd] [close + umount] netfs_unbuffered_write_iter_locked ... cifs_demultiplex_thread netfs_unbuffered_write cifs_issue_write netfs_wait_for_in_progress_stream [1] ... netfs_write_subrequest_terminated netfs_subreq_clear_in_progress netfs_wake_collector // wake [1] netfs_put_subrequest netfs_put_request queue_work(system_dfl_wq, xxx) [2] // dio write return cifs_close _cifsFileInfo_put // cfile->count 2->1 --cfile->count [3] // umount cifs_kill_sb kill_anon_super // warning triggered! shrink_dcache_for_umount [4] [system_dfl_wq] [5] netfs_free_request ... _cifsFileInfo_put // cfile->count 1->0 --cfile->count queue_work(fileinfo_put_wq, xxx) [fileinfo_put_wq] [6] cifsFileInfo_put_work cifsFileInfo_put_final dput If the umount path is triggered before [5], it results warning: BUG: Dentry 00000000eab1f070{i=9a917b66ae404fec,n=test} still in use (1) [unmount of cifs cifs] The existing per-inode ictx->io_count wait in cifs_evict_inode() does not help: it lives in the inode eviction path, which runs after shrink_dcache_for_umount() has already warned about the busy dentries. Fix it by adding a per-superblock outstanding-rreq counter that is incremented in cifs_init_request() and decremented in cifs_free_request(). In cifs_kill_sb(), before kill_anon_super(), wait for this counter to reach 0 - which guarantees that all cleanup_work for this sb have run and thus all relevant cfile puts are queued on fileinfo_put_wq or serverclose_wq. Then drain the workqueue so the dentry refs are dropped. This is a targeted wait, not a flush of the system-wide system_dfl_wq.
INFO
Published Date :
Aug. 15, 2026, 6:22 a.m.
Last Modified :
Aug. 17, 2026, 6:18 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Increment outstanding rreq counter in cifs_init_request.
- Decrement counter in cifs_free_request.
- Wait for counter to reach zero before unmount.
- Drain workqueue to drop dentry references.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-72315.
| URL | Resource |
|---|---|
| https://git.kernel.org/stable/c/75f5c412fa867efa0bf9b646bffe0d912109e84a | |
| https://git.kernel.org/stable/c/f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-72315 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-72315
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-72315 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-72315 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 17, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '340cea84f691c5206561bb2e0147158fe02070be', 'lessThan': 'f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214', 'versionType': 'git'}, {'status': 'affected', 'version': '340cea84f691c5206561bb2e0147158fe02070be', 'lessThan': '75f5c412fa867efa0bf9b646bffe0d912109e84a', 'versionType': 'git'}, {'status': 'affected', 'version': '708c276f516d27beaded7f372ac8111cee43926c', 'versionType': 'git'}, {'status': 'affected', 'version': '0629a1a187e424373364d681b42b101894bdb548', 'versionType': 'git'}, {'status': 'affected', 'version': '0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd', 'versionType': 'git'}, {'status': 'affected', 'version': 'f655467a9973f964b267871e5fef533ad5014494', 'versionType': 'git'}, {'status': 'affected', 'version': '30afc6ea72cc6cf7c8d579e79b64232801c38d08', 'versionType': 'git'}, {'status': 'affected', 'version': '6.1.167', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.6.130', 'lessThan': '6.7', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.12.78', 'lessThan': '6.13', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.18.20', 'lessThan': '6.19', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.19.10', 'lessThan': '6.20', 'versionType': 'semver'}], 'programFiles': ['fs/smb/client/cifs_fs_sb.h', 'fs/smb/client/cifsfs.c', 'fs/smb/client/connect.c', 'fs/smb/client/file.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '7.0'}, {'status': 'unaffected', 'version': '0', 'lessThan': '7.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc3', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/client/cifs_fs_sb.h', 'fs/smb/client/cifsfs.c', 'fs/smb/client/connect.c', 'fs/smb/client/file.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '340cea84f691c5206561bb2e0147158fe02070be', 'lessThan': 'f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214', 'versionType': 'git'}, {'status': 'affected', 'version': '340cea84f691c5206561bb2e0147158fe02070be', 'lessThan': '75f5c412fa867efa0bf9b646bffe0d912109e84a', 'versionType': 'git'}, {'status': 'affected', 'version': '708c276f516d27beaded7f372ac8111cee43926c', 'versionType': 'git'}, {'status': 'affected', 'version': '0629a1a187e424373364d681b42b101894bdb548', 'versionType': 'git'}, {'status': 'affected', 'version': '0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd', 'versionType': 'git'}, {'status': 'affected', 'version': 'f655467a9973f964b267871e5fef533ad5014494', 'versionType': 'git'}, {'status': 'affected', 'version': '30afc6ea72cc6cf7c8d579e79b64232801c38d08', 'versionType': 'git'}, {'status': 'affected', 'version': '6.1.167', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.6.130', 'lessThan': '6.7', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.12.78', 'lessThan': '6.13', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.18.20', 'lessThan': '6.19', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.19.10', 'lessThan': '6.20', 'versionType': 'semver'}], 'programFiles': ['fs/smb/client/cifs_fs_sb.h', 'fs/smb/client/cifsfs.c', 'fs/smb/client/connect.c', 'fs/smb/client/file.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '7.0'}, {'status': 'unaffected', 'version': '0', 'lessThan': '7.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/client/cifs_fs_sb.h', 'fs/smb/client/cifsfs.c', 'fs/smb/client/connect.c', 'fs/smb/client/file.c'], 'defaultStatus': 'affected'}] -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 15, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '340cea84f691c5206561bb2e0147158fe02070be', 'lessThan': 'f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214', 'versionType': 'git'}, {'status': 'affected', 'version': '340cea84f691c5206561bb2e0147158fe02070be', 'lessThan': '75f5c412fa867efa0bf9b646bffe0d912109e84a', 'versionType': 'git'}, {'status': 'affected', 'version': '708c276f516d27beaded7f372ac8111cee43926c', 'versionType': 'git'}, {'status': 'affected', 'version': '0629a1a187e424373364d681b42b101894bdb548', 'versionType': 'git'}, {'status': 'affected', 'version': '0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd', 'versionType': 'git'}, {'status': 'affected', 'version': 'f655467a9973f964b267871e5fef533ad5014494', 'versionType': 'git'}, {'status': 'affected', 'version': '30afc6ea72cc6cf7c8d579e79b64232801c38d08', 'versionType': 'git'}, {'status': 'affected', 'version': '6.1.167', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.6.130', 'lessThan': '6.7', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.12.78', 'lessThan': '6.13', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.18.20', 'lessThan': '6.19', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.19.10', 'lessThan': '6.20', 'versionType': 'semver'}], 'programFiles': ['fs/smb/client/cifs_fs_sb.h', 'fs/smb/client/cifsfs.c', 'fs/smb/client/connect.c', 'fs/smb/client/file.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '7.0'}, {'status': 'unaffected', 'version': '0', 'lessThan': '7.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.5', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc3', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/client/cifs_fs_sb.h', 'fs/smb/client/cifsfs.c', 'fs/smb/client/connect.c', 'fs/smb/client/file.c'], 'defaultStatus': 'affected'}] Added Description In the Linux kernel, the following vulnerability has been resolved: smb: client: fix busy dentry warning on unmount after DIO Commit c68337442f03 ("cifs: Fix busy dentry used after unmounting") fixed the issue in cifs where deferred close of a file led to a dentry reference count not being released in umount, by flushing deferredclose_wq in cifs_kill_sb() to solve it. However, the cifs DIO path suffers from the same busy-dentry problem caused by a delayed dentry reference-count release: [dio] [cifsd] [close + umount] netfs_unbuffered_write_iter_locked ... cifs_demultiplex_thread netfs_unbuffered_write cifs_issue_write netfs_wait_for_in_progress_stream [1] ... netfs_write_subrequest_terminated netfs_subreq_clear_in_progress netfs_wake_collector // wake [1] netfs_put_subrequest netfs_put_request queue_work(system_dfl_wq, xxx) [2] // dio write return cifs_close _cifsFileInfo_put // cfile->count 2->1 --cfile->count [3] // umount cifs_kill_sb kill_anon_super // warning triggered! shrink_dcache_for_umount [4] [system_dfl_wq] [5] netfs_free_request ... _cifsFileInfo_put // cfile->count 1->0 --cfile->count queue_work(fileinfo_put_wq, xxx) [fileinfo_put_wq] [6] cifsFileInfo_put_work cifsFileInfo_put_final dput If the umount path is triggered before [5], it results warning: BUG: Dentry 00000000eab1f070{i=9a917b66ae404fec,n=test} still in use (1) [unmount of cifs cifs] The existing per-inode ictx->io_count wait in cifs_evict_inode() does not help: it lives in the inode eviction path, which runs after shrink_dcache_for_umount() has already warned about the busy dentries. Fix it by adding a per-superblock outstanding-rreq counter that is incremented in cifs_init_request() and decremented in cifs_free_request(). In cifs_kill_sb(), before kill_anon_super(), wait for this counter to reach 0 - which guarantees that all cleanup_work for this sb have run and thus all relevant cfile puts are queued on fileinfo_put_wq or serverclose_wq. Then drain the workqueue so the dentry refs are dropped. This is a targeted wait, not a flush of the system-wide system_dfl_wq. Added Reference https://git.kernel.org/stable/c/75f5c412fa867efa0bf9b646bffe0d912109e84a Added Reference https://git.kernel.org/stable/c/f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214