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Commit 26c0c75e authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

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: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
Acked-by: default avatarBenny Halevy <bhalevy@panasas.com>
parent e0c82336

fs/nfsd/nfs4proc.c

+1 −0
Original line number Diff line number Diff line
@@ -1027,6 +1027,7 @@ nfsd4_proc_compound(struct svc_rqst *rqstp, 
	resp->rqstp = rqstp;

	resp->cstate.minorversion = args->minorversion;

	resp->cstate.replay_owner = NULL;

	resp->cstate.session = NULL;

	fh_init(&resp->cstate.current_fh, NFS4_FHSIZE);

	fh_init(&resp->cstate.save_fh, NFS4_FHSIZE);

	/* Use the deferral mechanism only for NFSv4.0 compounds */

fs/nfsd/nfs4state.c

+3 −4
Original line number Diff line number Diff line
@@ -1443,11 +1443,10 @@ nfsd4_sequence(struct svc_rqst *rqstp, 
	cstate->slot = slot;

	cstate->session = session;



	/* Hold a session reference until done processing the compound:

	 * nfsd4_put_session called only if the cstate slot is set.

	 */

	nfsd4_get_session(session);

out:

	/* Hold a session reference until done processing the compound. */

	if (cstate->session)

		nfsd4_get_session(cstate->session);

	spin_unlock(&sessionid_lock);

	/* Renew the clientid on success and on replay */

	if (cstate->session) {

fs/nfsd/nfs4xdr.c

+6 −4
Original line number Diff line number Diff line
@@ -3306,10 +3306,12 @@ nfs4svc_encode_compoundres(struct svc_rqst *rqstp, __be32 *p, struct nfsd4_compo 
		iov = &rqstp->rq_res.head[0];

	iov->iov_len = ((char*)resp->p) - (char*)iov->iov_base;

	BUG_ON(iov->iov_len > PAGE_SIZE);

	if (nfsd4_has_session(cs) && cs->status != nfserr_replay_cache) {

	if (nfsd4_has_session(cs)) {

		if (cs->status != nfserr_replay_cache) {

			nfsd4_store_cache_entry(resp);

			dprintk("%s: SET SLOT STATE TO AVAILABLE\n", __func__);

			resp->cstate.slot->sl_inuse = false;

		}

		nfsd4_put_session(resp->cstate.session);

	}

	return 1;