4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Scott Mayhew <redacted>

commit 01310bb7c9c98752cc763b36532fab028e0f8f81 upstream.

Make sure we have a saved filehandle, otherwise we'll oops with a null
pointer dereference in nfs4_preprocess_stateid_op().

Signed-off-by: Scott Mayhew <redacted>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/nfsd/nfs4proc.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c

@@ -1037,6 +1037,9 @@ nfsd4_verify_copy(struct svc_rqst *rqstp
 {
 	__be32 status;
 
+	if (!cstate->save_fh.fh_dentry)
+		return nfserr_nofilehandle;
+
 	status = nfs4_preprocess_stateid_op(rqstp, cstate, &cstate->save_fh,
 					    src_stateid, RD_STATE, src, NULL);
 	if (status) {