From: Jeff Layton <jlayton@kernel.org> stable inclusion from stable-v5.10.270 commit 863b6e995665472f2af5be2436a874ab6a9e5ac6 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/18933 CVE: CVE-2026-89669 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 129643893b79f8a3c6b72045f933fbab5ee424ca upstream. 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. Fixes: 624322f1adc5 ("NFSD add COPY_NOTIFY operation") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Jeff Layton <jlayton@kernel.org> Link: https://patch.msgid.link/20260710-nfsd-testing-v3-4-a0ff7db6aa3e@kernel.org Signed-off-by: Chuck Lever <cel@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: fs/nfsd/nfs4proc.c fs/nfsd/nfs4state.c [Context conflicts] Signed-off-by: Lu Jialin <lujialin4@huawei.com> --- fs/nfsd/nfs4proc.c | 16 +++++++++------- fs/nfsd/nfs4state.c | 10 +++++++++- 2 files changed, 18 insertions(+), 8 deletions(-) diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index ecbde42093d5..5beabc0ced52 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1613,7 +1613,6 @@ nfsd4_copy_notify(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id); struct nfs4_stid *stid; struct nfs4_cpntf_state *cps; - struct nfs4_client *clp = cstate->clp; status = nfs4_preprocess_stateid_op(rqstp, cstate, &cstate->current_fh, &cn->cpn_src_stateid, RD_STATE, NULL, @@ -1625,12 +1624,14 @@ nfsd4_copy_notify(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, cn->cpn_nsec = 0; status = nfserrno(-ENOMEM); + /* + * The returned cps is published and fully initialized, and carries an + * extra reference for us; drop it once we are done with it. + */ cps = nfs4_alloc_init_cpntf_state(nn, stid); if (!cps) goto out; memcpy(&cn->cpn_cnr_stateid, &cps->cp_stateid.stid, sizeof(stateid_t)); - memcpy(&cps->cp_p_stateid, &stid->sc_stateid, sizeof(stateid_t)); - memcpy(&cps->cp_p_clid, &clp->cl_clientid, sizeof(clientid_t)); /* For now, only return one server address in cpn_src, the * address used by the client to connect to this server. @@ -1639,10 +1640,11 @@ nfsd4_copy_notify(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, status = nfsd4_set_netaddr((struct sockaddr *)&rqstp->rq_daddr, &cn->cpn_src.u.nl4_addr); WARN_ON_ONCE(status); - if (status) { - nfs4_put_cpntf_state(nn, cps); - goto out; - } + /* + * Drop our extra reference. The membership reference keeps the entry + * alive for a later inter-server READ, or until the laundromat reaps it. + */ + nfs4_put_cpntf_state(nn, cps); out: nfs4_put_stid(stid); return status; diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 7bfe0a6bc5fd..d930100afdd6 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -834,7 +834,15 @@ struct nfs4_cpntf_state *nfs4_alloc_init_cpntf_state(struct nfsd_net *nn, if (!cps) return NULL; cps->cpntf_time = ktime_get_boottime_seconds(); - refcount_set(&cps->cp_stateid.sc_count, 1); + /* + * Fully initialize the entry before nfs4_init_cp_state() publishes it, + * since a concurrent OFFLOAD_CANCEL could then free it. Take an extra + * reference for the caller (dropped with nfs4_put_cpntf_state()). + */ + memcpy(&cps->cp_p_stateid, &p_stid->sc_stateid, sizeof(stateid_t)); + memcpy(&cps->cp_p_clid, &p_stid->sc_client->cl_clientid, + sizeof(clientid_t)); + refcount_set(&cps->cp_stateid.sc_count, 2); if (!nfs4_init_cp_state(nn, &cps->cp_stateid, NFS4_COPYNOTIFY_STID)) goto out_free; spin_lock(&nn->s2s_cp_lock); -- 2.34.1