nfsd4: fix unlikely race in session replay case
In the replay case, the renew_client(session->se_client); happens after we've droppped the sessionid_lock, and without holding a reference on the session; so there's nothing preventing the session being freed before we get here. Thanks to Benny Halevy for catching a bug in an earlier version of this patch. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu> Acked-by: Benny Halevy <bhalevy@panasas.com>
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@ -1027,6 +1027,7 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
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resp->rqstp = rqstp;
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resp->rqstp = rqstp;
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resp->cstate.minorversion = args->minorversion;
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resp->cstate.minorversion = args->minorversion;
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resp->cstate.replay_owner = NULL;
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resp->cstate.replay_owner = NULL;
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resp->cstate.session = NULL;
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fh_init(&resp->cstate.current_fh, NFS4_FHSIZE);
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fh_init(&resp->cstate.current_fh, NFS4_FHSIZE);
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fh_init(&resp->cstate.save_fh, NFS4_FHSIZE);
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fh_init(&resp->cstate.save_fh, NFS4_FHSIZE);
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/* Use the deferral mechanism only for NFSv4.0 compounds */
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/* Use the deferral mechanism only for NFSv4.0 compounds */
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@ -1443,11 +1443,10 @@ nfsd4_sequence(struct svc_rqst *rqstp,
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cstate->slot = slot;
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cstate->slot = slot;
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cstate->session = session;
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cstate->session = session;
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/* Hold a session reference until done processing the compound:
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* nfsd4_put_session called only if the cstate slot is set.
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*/
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nfsd4_get_session(session);
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out:
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out:
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/* Hold a session reference until done processing the compound. */
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if (cstate->session)
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nfsd4_get_session(cstate->session);
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spin_unlock(&sessionid_lock);
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spin_unlock(&sessionid_lock);
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/* Renew the clientid on success and on replay */
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/* Renew the clientid on success and on replay */
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if (cstate->session) {
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if (cstate->session) {
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@ -3306,10 +3306,12 @@ nfs4svc_encode_compoundres(struct svc_rqst *rqstp, __be32 *p, struct nfsd4_compo
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iov = &rqstp->rq_res.head[0];
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iov = &rqstp->rq_res.head[0];
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iov->iov_len = ((char*)resp->p) - (char*)iov->iov_base;
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iov->iov_len = ((char*)resp->p) - (char*)iov->iov_base;
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BUG_ON(iov->iov_len > PAGE_SIZE);
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BUG_ON(iov->iov_len > PAGE_SIZE);
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if (nfsd4_has_session(cs) && cs->status != nfserr_replay_cache) {
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if (nfsd4_has_session(cs)) {
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if (cs->status != nfserr_replay_cache) {
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nfsd4_store_cache_entry(resp);
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nfsd4_store_cache_entry(resp);
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dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__);
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dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__);
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resp->cstate.slot->sl_inuse = false;
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resp->cstate.slot->sl_inuse = false;
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}
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nfsd4_put_session(resp->cstate.session);
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nfsd4_put_session(resp->cstate.session);
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}
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}
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return 1;
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return 1;
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