Linux Kernel NFS STID IDR Dangling Deref on Lease Set Fail
CVE-2026-53399 Published on July 19, 2026
nfsd: release layout stid on setlease failure
In the Linux kernel, the following vulnerability has been resolved:
nfsd: release layout stid on setlease failure
nfs4_alloc_stid() publishes the new stid into cl->cl_stateids via
idr_alloc_cyclic() under cl_lock before returning to
nfsd4_alloc_layout_stateid(). When nfsd4_layout_setlease() then
fails, the error path frees the layout stateid directly with
kmem_cache_free() without ever calling idr_remove(), leaving the
IDR slot pointing at freed slab memory. Any subsequent IDR walker
(states_show, client teardown) dereferences the dangling pointer.
The correct teardown for an IDR-published stid is nfs4_put_stid(),
which removes the IDR slot under cl_lock, dispatches sc_free
(nfsd4_free_layout_stateid) to release ls->ls_file via
nfsd4_close_layout(), and drops the nfs4_file reference in its
tail.
A second issue blocks that switch: nfsd4_free_layout_stateid()
unconditionally inspects ls->ls_fence_work via
delayed_work_pending() under ls_lock, but
INIT_DELAYED_WORK(&ls->ls_fence_work, ...) currently runs only
after the setlease call. On the setlease-failure path the
destructor would touch an uninitialized delayed_work.
nfsd4_alloc_layout_stateid()
nfs4_alloc_stid() /* idr_alloc_cyclic under cl_lock */
nfsd4_layout_setlease() /* fails */
nfs4_put_stid()
nfsd4_free_layout_stateid()
delayed_work_pending(&ls->ls_fence_work) /* needs INIT */
nfsd4_close_layout() /* nfsd_file_put(ls->ls_file) */
put_nfs4_file()
Fix by hoisting the ls_fenced / ls_fence_delay / INIT_DELAYED_WORK
initialization above the nfsd4_layout_setlease() call, and replace
the manual nfsd_file_put + put_nfs4_file + kmem_cache_free cleanup
with a single nfs4_put_stid(stp).
Products Associated with CVE-2026-53399
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Affected Versions
Linux:- Version c5c707f96fc9a6e5a57ca5baac892673270abe3d and below d788ef40a7517d22c97ab01700e4ae4c611b6f2f is affected.
- Version c5c707f96fc9a6e5a57ca5baac892673270abe3d and below 2e0a5d6d62600b8c614d1b55e50ef94035d6adf9 is affected.
- Version c5c707f96fc9a6e5a57ca5baac892673270abe3d and below 7bbb7ce74051c8be4b69ff44ce3db370600dae61 is affected.
- Version c5c707f96fc9a6e5a57ca5baac892673270abe3d and below 48a586e382e4db1dbf958d44b63e081df5f8ed04 is affected.
- Version c5c707f96fc9a6e5a57ca5baac892673270abe3d and below d369e5edfaaf83a448016e2f1da392b2174be801 is affected.
- Version c5c707f96fc9a6e5a57ca5baac892673270abe3d and below 8dee7c278f1c2b5bb80e17a6281c3812fc8b0cdd is affected.
- Version c5c707f96fc9a6e5a57ca5baac892673270abe3d and below 83c2b7797742339bb768f83935f7ca33950db138 is affected.
- Version c5c707f96fc9a6e5a57ca5baac892673270abe3d and below 30d55c8aabb261bc3f427d6b9aae7ef6206063f9 is affected.
- Version 4.0 is affected.
- Before 4.0 is unaffected.
- Version 5.10.261, <= 5.10.* is unaffected.
- Version 5.15.212, <= 5.15.* is unaffected.
- Version 6.1.178, <= 6.1.* is unaffected.
- Version 6.6.145, <= 6.6.* is unaffected.
- Version 6.12.96, <= 6.12.* is unaffected.
- Version 6.18.39, <= 6.18.* is unaffected.
- Version 7.1.3, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.