In the Linux kernel, the following vulnerability has been resolved:
nfs: use nfsi->rwsem to protect traversal of the file lock list
Lingfeng identified a bug and suggested two solutions, but both appear
to have issues.
Generally, we cannot release flc_lock while iterating over the file lock
list to avoid use-after-free (UAF) problems with file locks. However,
functions like nfs_delegation_claim_locks and nfs4_reclaim_locks cannot
adhere to this rule because recover_lock or nfs4_lock_delegation_recall
may take a long time. To resolve this, NFS switches to using nfsi->rwsem
for the same protection, and nfs_reclaim_locks follows this approach.
Although nfs_delegation_claim_locks uses so_delegreturn_mutex instead,
this is inadequate since a single inode can have multiple nfs4_state
instances. Therefore, the fix is to also use nfsi->rwsem in this case.
Furthermore, after commit c69899a17ca4 ("NFSv4: Update of VFS byte range
lock must be atomic with the stateid update"), the functions
nfs4_locku_done and nfs4_lock_done also break this rule because they
call locks_lock_inode_wait without holding nfsi->rwsem. Simply adding
this protection could cause many deadlocks, so instead, the call to
locks_lock_inode_wait is moved into _nfs4_proc_setlk. Regarding the bug
fixed by commit c69899a17ca4 ("NFSv4: Update of VFS byte range
lock must be atomic with the stateid update"), it has been resolved
after commit 0460253913e5 ("NFSv4: nfs4_do_open() is incorrectly triggering
state recovery") because all slots are drained before calling
nfs4_do_reclaim, which prevents concurrent stateid changes along this path.
Also, nfs_delegation_claim_locks does not cause this concurrency either
since when _nfs4_proc_setlk is called with NFS_DELEGATED_STATE, no RPC is
sent, so nfs4_lock_done is not called. Therefore,
nfs4_lock_delegation_recall from nfs_delegation_claim_locks is the first
time the stateid is set.
nfs: use nfsi->rwsem to protect traversal of the file lock list
Lingfeng identified a bug and suggested two solutions, but both appear
to have issues.
Generally, we cannot release flc_lock while iterating over the file lock
list to avoid use-after-free (UAF) problems with file locks. However,
functions like nfs_delegation_claim_locks and nfs4_reclaim_locks cannot
adhere to this rule because recover_lock or nfs4_lock_delegation_recall
may take a long time. To resolve this, NFS switches to using nfsi->rwsem
for the same protection, and nfs_reclaim_locks follows this approach.
Although nfs_delegation_claim_locks uses so_delegreturn_mutex instead,
this is inadequate since a single inode can have multiple nfs4_state
instances. Therefore, the fix is to also use nfsi->rwsem in this case.
Furthermore, after commit c69899a17ca4 ("NFSv4: Update of VFS byte range
lock must be atomic with the stateid update"), the functions
nfs4_locku_done and nfs4_lock_done also break this rule because they
call locks_lock_inode_wait without holding nfsi->rwsem. Simply adding
this protection could cause many deadlocks, so instead, the call to
locks_lock_inode_wait is moved into _nfs4_proc_setlk. Regarding the bug
fixed by commit c69899a17ca4 ("NFSv4: Update of VFS byte range
lock must be atomic with the stateid update"), it has been resolved
after commit 0460253913e5 ("NFSv4: nfs4_do_open() is incorrectly triggering
state recovery") because all slots are drained before calling
nfs4_do_reclaim, which prevents concurrent stateid changes along this path.
Also, nfs_delegation_claim_locks does not cause this concurrency either
since when _nfs4_proc_setlk is called with NFS_DELEGATED_STATE, no RPC is
sent, so nfs4_lock_done is not called. Therefore,
nfs4_lock_delegation_recall from nfs_delegation_claim_locks is the first
time the stateid is set.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
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| Linux | Linux | affected |
|
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Advisories
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Fixes
Solution
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Workaround
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References
History
Sat, 15 Aug 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: nfs: use nfsi->rwsem to protect traversal of the file lock list Lingfeng identified a bug and suggested two solutions, but both appear to have issues. Generally, we cannot release flc_lock while iterating over the file lock list to avoid use-after-free (UAF) problems with file locks. However, functions like nfs_delegation_claim_locks and nfs4_reclaim_locks cannot adhere to this rule because recover_lock or nfs4_lock_delegation_recall may take a long time. To resolve this, NFS switches to using nfsi->rwsem for the same protection, and nfs_reclaim_locks follows this approach. Although nfs_delegation_claim_locks uses so_delegreturn_mutex instead, this is inadequate since a single inode can have multiple nfs4_state instances. Therefore, the fix is to also use nfsi->rwsem in this case. Furthermore, after commit c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update"), the functions nfs4_locku_done and nfs4_lock_done also break this rule because they call locks_lock_inode_wait without holding nfsi->rwsem. Simply adding this protection could cause many deadlocks, so instead, the call to locks_lock_inode_wait is moved into _nfs4_proc_setlk. Regarding the bug fixed by commit c69899a17ca4 ("NFSv4: Update of VFS byte range lock must be atomic with the stateid update"), it has been resolved after commit 0460253913e5 ("NFSv4: nfs4_do_open() is incorrectly triggering state recovery") because all slots are drained before calling nfs4_do_reclaim, which prevents concurrent stateid changes along this path. Also, nfs_delegation_claim_locks does not cause this concurrency either since when _nfs4_proc_setlk is called with NFS_DELEGATED_STATE, no RPC is sent, so nfs4_lock_done is not called. Therefore, nfs4_lock_delegation_recall from nfs_delegation_claim_locks is the first time the stateid is set. | |
| Title | nfs: use nfsi->rwsem to protect traversal of the file lock list | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T05:57:13.752Z
Reserved: 2026-08-09T03:40:39.934Z
Link: CVE-2026-72472
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-15T06:22:21.313
Modified: 2026-08-15T06:22:21.313
Link: CVE-2026-72472
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.