SUNRPC: return proper error from gss_wrap_req_priv

don't return 0 if snd_buf->len really greater than snd_buf->buflen

Signed-off-by: Chen Hanxiao <chenhx.fnst@fujitsu.com>
Fixes: 0c77668 ("SUNRPC: Introduce trace points in rpc_auth_gss.ko")
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/auth_gss/auth_gss.c

@@ -1875,8 +1875,10 @@ gss_wrap_req_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
 	offset = (u8 *)p - (u8 *)snd_buf->head[0].iov_base;
 	maj_stat = gss_wrap(ctx->gc_gss_ctx, offset, snd_buf, inpages);
 	/* slack space should prevent this ever happening: */
-	if (unlikely(snd_buf->len > snd_buf->buflen))
+	if (unlikely(snd_buf->len > snd_buf->buflen)) {
+		status = -EIO;
 		goto wrap_failed;
+	}
 	/* We're assuming that when GSS_S_CONTEXT_EXPIRED, the encryption was
 	 * done anyway, so it's safe to put the request on the wire: */
 	if (maj_stat == GSS_S_CONTEXT_EXPIRED)