Re: [PATCH] NFSD: Fix a null reference case in find_or_create_lock_stateid()

[Jeff Layton <jlayton@redhat.com>]

On Wed, 2017-01-18 at 19:04 +0800, Kinglong Mee wrote:
> 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().
> 
> Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
> ---
>  fs/nfsd/nfs4layouts.c |  5 +++--
>  fs/nfsd/nfs4state.c   | 19 ++++++++-----------
>  fs/nfsd/state.h       |  4 ++--
>  3 files changed, 13 insertions(+), 15 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
> index 596205d..1fc07a9 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 4b4beaa..a0dee8a 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -633,8 +633,8 @@ find_or_hash_clnt_odstate(struct nfs4_file *fp, struct nfs4_clnt_odstate *new)
>  	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 @@ struct nfs4_stid *nfs4_alloc_stid(struct nfs4_client *cl,
>  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 c939936..4516e8b 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);

Nice cleanup too:

Reviewed-by: Jeff Layton <jlayton@redhat.com>