nfsd: revoke copy-notify stateids before dropping their reference

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89663
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:52 UTC
Updated2026-09-11 20:19:52 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: nfsd: revoke copy-notify stateids before dropping their reference Copy-notify stateids live in the s2s_cp_stateids IDR and on their parent stid's sc_cp_list, pinned by a single membership reference. _free_cpntf_state_locked() only unlinks an entry once its refcount reaches zero, so any revoke path that runs while a concurrent find_cpntf_state()/manage_cpntf_state() holder has elevated cs_count drops the reference without unlinking, leaving the entry discoverable with its membership reference already consumed. A second revoke or a laundromat tick then frees it while the reader still holds the pointer -- a KASAN-detectable use-after-free at the reader's nfs4_put_cpntf_state(). This affected all three revoke paths: - The parent-stid drain (nfs4_free_cpntf_statelist()) repeatedly called _free_cpntf_state_locked() on the first list entry; a holder that had bumped cs_count made it return early, so the next iteration re-decremented and burned the holder's reference. - OFFLOAD_CANCEL (manage_cpntf_state()) and laundromat expiry likewise used _free_cpntf_state_locked() and could drop 2->1 without unlinking. Add revoke_cpntf_state_locked(), which unhashes the entry from the IDR and sc_cp_list first (deferring the final free to any holder), and use it from all three revoke paths. The drain now walks with list_for_each_entry_safe() and revokes each entry unconditionally, so it terminates in one pass per entry regardless of cs_count. The unhash is gated on !list_empty(&cps->cp_list); the idr_remove() gate matters because idr_alloc_cyclic() may have recycled the so_id by then. Keep _free_cpntf_state_locked() for the reference-holder put path only, where a concurrent revoke may already have unlinked the entry (its list_del_init() then a no-op).

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 624322f1adc58acd0b69f77a6ddc764207e97241 6b8149448cdcb476fba4559d1ecc247efee9971b git Not specified
CNA Linux Linux affected 624322f1adc58acd0b69f77a6ddc764207e97241 b56d2c5f01cddbeca7d11cce81d97db4ec9a464f git Not specified
CNA Linux Linux affected 624322f1adc58acd0b69f77a6ddc764207e97241 ff8a3cff02b92b2a82f1a9876038fcf953ae9c25 git Not specified
CNA Linux Linux affected 624322f1adc58acd0b69f77a6ddc764207e97241 3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7 git Not specified
CNA Linux Linux affected 5.6 Not specified
CNA Linux Linux unaffected 5.6 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/b56d2c5f01cddbeca7d11cce81d97db4ec9a464f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ff8a3cff02b92b2a82f1a9876038fcf953ae9c25 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6b8149448cdcb476fba4559d1ecc247efee9971b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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