gss:spkm3 miss returning error to caller when import security context

spkm3 miss returning error to up layer when import security context,
it may be return ok though it has failed to import security context.
Signed-off-by: NBian Naimeng <biannm@cn.fujitsu.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

net/sunrpc/auth_gss/gss_spkm3_mech.c

@@ -100,6 +100,7 @@ gss_import_sec_context_spkm3(const void *p, size_t len,
 	if (version != 1) {
 		dprintk("RPC:       unknown spkm3 token format: "
 				"obsolete nfs-utils?\n");
+		p = ERR_PTR(-EINVAL);
 		goto out_err_free_ctx;
 	}
 
@@ -135,8 +136,10 @@ gss_import_sec_context_spkm3(const void *p, size_t len,
 	if (IS_ERR(p))
 		goto out_err_free_intg_alg;
 
-	if (p != end)
+	if (p != end) {
+		p = ERR_PTR(-EFAULT);
 		goto out_err_free_intg_key;
+	}
 
 	ctx_id->internal_ctx_id = ctx;