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>

3 files changed, 13 insertions, 15 deletions

diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
index 42aace4fc4c8..64813697f4c4 100644
--- a/fs/nfsd/nfs4layouts.c
+++ b/fs/nfsd/nfs4layouts.c
@@ -223,10 +223,11 @@ nfsd4_alloc_layout_stateid(struct nfsd4_compound_state *cstate,
         struct nfs4_layout_stateid *ls;
         struct nfs4_stid *stp;
 
-        stp = nfs4_alloc_stid(cstate->clp, nfs4_layout_stateid_cache);
+        stp = nfs4_alloc_stid(cstate->clp, nfs4_layout_stateid_cache,
+                                        nfsd4_free_layout_stateid);
         if (!stp)
                 return NULL;
-        stp->sc_free = nfsd4_free_layout_stateid;
+
         get_nfs4_file(fp);
         stp->sc_file = fp;
 
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 4b4beaaa4eaa..a0dee8ae9f97 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -633,8 +633,8 @@ out:
         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 @@ struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl,
         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 @@ out_free:
 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 @@ alloc_init_deleg(struct nfs4_client *clp, struct svc_fh *current_fh,
                 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 @@ init_lock_stateid(struct nfs4_ol_stateid *stp, struct nfs4_lockowner *lo,
         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 @@ find_or_create_lock_stateid(struct nfs4_lockowner *lo, struct nfs4_file *fi,
         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;
 
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index c9399366f9df..4516e8b7d776 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -603,8 +603,8 @@ extern __be32 nfs4_preprocess_stateid_op(struct svc_rqst *rqstp,
 __be32 nfsd4_lookup_stateid(struct nfsd4_compound_state *cstate,
                      stateid_t *stateid, unsigned char typemask,
                      struct nfs4_stid **s, struct nfsd_net *nn);
-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 *));
 void nfs4_unhash_stid(struct nfs4_stid *s);
 void nfs4_put_stid(struct nfs4_stid *s);
 void nfs4_inc_and_copy_stateid(stateid_t *dst, struct nfs4_stid *stid);