commit 743146d347f3141cd5a82f4c9aace1790a7537b9
author Kinglong Mee <kinglongmee@gmail.com> Wed Jan 18 19:04:42 2017 +0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> Thu Feb 09 08:08:27 2017 +0100
tree 55290acb62309361a8f5eba79f90553321ac5a88
parent 4c953848c95b74def08172b07c04a773071f69ee

NFSD: Fix a null reference case in find_or_create_lock_stateid()

commit d19fb70dd68c4e960e2ac09b0b9c79dfdeefa726 upstream.

nfsd assigns the nfs4_free_lock_stateid to .sc_free in init_lock_stateid().

If nfsd doesn't go through init_lock_stateid() and put stateid at end,
there is a NULL reference to .sc_free when calling nfs4_put_stid(ns).

This patch let the nfs4_stid.sc_free assignment to nfs4_alloc_stid().

Fixes: 356a95ece7aa "nfsd: clean up races in lock stateid searching..."
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/nfsd/nfs4state.c

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 4b4beaa..a0dee8a 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -633,8 +633,8 @@
 	return co;
 }
 
-struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl,
-					 struct kmem_cache *slab)
+struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl, struct kmem_cache *slab,
+				  void (*sc_free)(struct nfs4_stid *))
 {
 	struct nfs4_stid *stid;
 	int new_id;
@@ -650,6 +650,8 @@
 	idr_preload_end();
 	if (new_id < 0)
 		goto out_free;
+
+	stid->sc_free = sc_free;
 	stid->sc_client = cl;
 	stid->sc_stateid.si_opaque.so_id = new_id;
 	stid->sc_stateid.si_opaque.so_clid = cl->cl_clientid;
@@ -675,15 +677,12 @@
 static struct nfs4_ol_stateid * nfs4_alloc_open_stateid(struct nfs4_client *clp)
 {
 	struct nfs4_stid *stid;
-	struct nfs4_ol_stateid *stp;
 
-	stid = nfs4_alloc_stid(clp, stateid_slab);
+	stid = nfs4_alloc_stid(clp, stateid_slab, nfs4_free_ol_stateid);
 	if (!stid)
 		return NULL;
 
-	stp = openlockstateid(stid);
-	stp->st_stid.sc_free = nfs4_free_ol_stateid;
-	return stp;
+	return openlockstateid(stid);
 }
 
 static void nfs4_free_deleg(struct nfs4_stid *stid)
@@ -781,11 +780,10 @@
 		goto out_dec;
 	if (delegation_blocked(&current_fh->fh_handle))
 		goto out_dec;
-	dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab));
+	dp = delegstateid(nfs4_alloc_stid(clp, deleg_slab, nfs4_free_deleg));
 	if (dp == NULL)
 		goto out_dec;
 
-	dp->dl_stid.sc_free = nfs4_free_deleg;
 	/*
 	 * delegation seqid's are never incremented.  The 4.1 special
 	 * meaning of seqid 0 isn't meaningful, really, but let's avoid
@@ -5580,7 +5578,6 @@
 	stp->st_stateowner = nfs4_get_stateowner(&lo->lo_owner);
 	get_nfs4_file(fp);
 	stp->st_stid.sc_file = fp;
-	stp->st_stid.sc_free = nfs4_free_lock_stateid;
 	stp->st_access_bmap = 0;
 	stp->st_deny_bmap = open_stp->st_deny_bmap;
 	stp->st_openstp = open_stp;
@@ -5623,7 +5620,7 @@
 	lst = find_lock_stateid(lo, fi);
 	if (lst == NULL) {
 		spin_unlock(&clp->cl_lock);
-		ns = nfs4_alloc_stid(clp, stateid_slab);
+		ns = nfs4_alloc_stid(clp, stateid_slab, nfs4_free_lock_stateid);
 		if (ns == NULL)
 			return NULL;