CVE-2026-89669

Summary

In the Linux kernel, the following vulnerability has been resolved:

nfsd: initialize copy-notify stateid before publishing it

nfsd4_copy_notify() finished initializing the cpntf state after nfs4_alloc_init_cpntf_state() had already linked it into the s2s_cp_stateids IDR and the parent's sc_cp_list, with cs_count == 1 (the membership reference) and none held for the caller. A racing OFFLOAD_CANCEL (crafted cl_id == nn->s2s_cp_cl_id plus the guessable so_id) could reach manage_cpntf_state() and free the entry, turning the caller's subsequent cpn_cnr_stateid read and cp_p_stateid/cp_p_clid writes into use-after-free. The owning clientid was also only recorded after publication, so it could not gate an ownership check in that window.

Record cp_p_stateid and cp_p_clid inside nfs4_alloc_init_cpntf_state() before nfs4_init_cp_state() publishes the entry, and return it with an extra reference. The caller reads the stateid under that reference and drops it with nfs4_put_cpntf_state(); on a late error the laundromat reaps the entry.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/e08a3dcaca0505f861e344a387f37f94d95dbdc2
• https://git.kernel.org/stable/c/a4d7fedcaaf33e60a01e53eafca9041ef966212f
• https://git.kernel.org/stable/c/4cdef96892f4fa6e70c405b6e8f2fd6972f3b64b
• https://git.kernel.org/stable/c/129643893b79f8a3c6b72045f933fbab5ee424ca

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