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CVE-2026-72315— smb: client: fix busy dentry warning on unmount after DIO

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.1.167至6.2之前版本、6.6.130至6.7之前版本、6.12.78至6.13之前版本、6.18.20至6.19之前版本和6.19.10至6.20之前版本存在安全漏洞，该漏洞源于cifs DIO路径中dentry引用计数延迟释放，在卸载时可能导致系统触发busy dentry警告。

CVSS 7.8 · High EPSS 0.17% · P6

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 340cea84f691c5206561bb2e0147158fe02070be< f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214 affected
340cea84f691c5206561bb2e0147158fe02070be< 75f5c412fa867efa0bf9b646bffe0d912109e84a affected
708c276f516d27beaded7f372ac8111cee43926c affected
0629a1a187e424373364d681b42b101894bdb548 affected
0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd affected
f655467a9973f964b267871e5fef533ad5014494 affected
30afc6ea72cc6cf7c8d579e79b64232801c38d08 affected
6.1.167< 6.2 affected
… +8 more rows
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I. Basic Information for CVE-2026-72315

Vulnerability Information
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Vulnerability Title
smb: client: fix busy dentry warning on unmount after DIO
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel 6.1.167至6.2之前版本、6.6.130至6.7之前版本、6.12.78至6.13之前版本、6.18.20至6.19之前版本和6.19.10至6.20之前版本存在安全漏洞，该漏洞源于cifs DIO路径中dentry引用计数延迟释放，在卸载时可能导致系统触发busy dentry警告。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 340cea84f691c5206561bb2e0147158fe02070be ~ f0eac9c3c3711f24efc2aaf12b8ec3e54a38c214 -
Linux Linux 7.0 -

II. Public POCs for CVE-2026-72315

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III. Intelligence Information for CVE-2026-72315

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Patches & Fixes for CVE-2026-72315 (1)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72472 9.8 CRITICAL nfs: use nfsi->rwsem to protect traversal of the file lock list
CVE-2026-74428 9.8 CRITICAL rxrpc: Fix double unlock in rxrpc_recvmsg()
CVE-2026-72473 9.8 CRITICAL xprtrdma: Decouple req recycling from RPC completion
CVE-2026-72098 9.8 CRITICAL dm-verity: fix buffer overflow in FEC calculation
CVE-2026-74433 9.8 CRITICAL rxrpc: Fix UAF in rxgk_issue_challenge()
CVE-2026-74434 9.8 CRITICAL rxrpc: Don't move a peeked OOB message onto the pending queue
CVE-2026-72299 9.8 CRITICAL tipc: restrict socket queue dumps in enqueue tracepoints
CVE-2026-72477 9.8 CRITICAL fs/ntfs3: call _ntfs_bad_inode() when failing to rename
CVE-2026-72249 9.8 CRITICAL netfilter: flowtable: use dst in this direction when pushing IPIP header
CVE-2026-72251 9.8 CRITICAL netfilter: nf_nat_sip: reload possible stale data pointer
CVE-2026-72130 9.8 CRITICAL nvmet-auth: reject short AUTH_RECEIVE buffers
CVE-2026-72137 9.8 CRITICAL xfrm: nat_keepalive: avoid double free on send error

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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