5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jeff Layton commit 6bdbfab96e0cf25e5f57dac5c09dc1749751a4bf upstream. On the OFFLOAD_CANCEL path (clp != NULL), manage_cpntf_state() freed the target cpntf state without checking ownership. The lookup key st->si_opaque.so_id is allocated cyclically (guessable) and the embedded clientid is the fixed per-net nn->s2s_cp_cl_id, so any authenticated NFSv4.2 client could cancel and free another client's copy-notify stateid. Compare the creating clientid recorded in state->cp_p_clid against the requesting client's cl_clientid and return nfserr_bad_stateid on a mismatch instead of freeing the entry. Fixes: ce0887ac96d3 ("NFSD add nfs4 inter ssc to nfsd4_copy") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260710-nfsd-testing-v3-5-a0ff7db6aa3e@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfs4state.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -6621,10 +6621,20 @@ __be32 manage_cpntf_state(struct nfsd_ne state = NULL; goto unlock; } - if (!clp) + if (!clp) { refcount_inc(&state->cp_stateid.cs_count); - else + } else if (memcmp(&clp->cl_clientid, &state->cp_p_clid, + sizeof(clientid_t))) { + /* + * OFFLOAD_CANCEL: only the creating client may cancel. + * so_id is guessable, so without this check any client + * could free another's cpntf state. + */ + state = NULL; + goto unlock; + } else { _free_cpntf_state_locked(nn, state); + } } unlock: spin_unlock(&nn->s2s_cp_lock);