From dcec5627d17dd894d95676b43c42d56e2b03547c Mon Sep 17 00:00:00 2001
From: iceman1001 <iceman@iuse.se>
Date: Mon, 18 Mar 2019 13:41:59 +0100
Subject: [PATCH] chg: unsigned byte can't be less than zero.

---
 armsrc/desfire_crypto.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/armsrc/desfire_crypto.c b/armsrc/desfire_crypto.c
index fd3f30d0d..111db131c 100644
--- a/armsrc/desfire_crypto.c
+++ b/armsrc/desfire_crypto.c
@@ -313,7 +313,7 @@ void *mifare_cryto_postprocess_data(desfiretag_t tag, void *data, size_t *nbytes
                 case AS_LEGACY:
                     if (communication_settings & MAC_VERIFY) {
                         *nbytes -= key_macing_length(key);
-                        if (*nbytes <= 0) {
+                        if (*nbytes == 0) {
                             *nbytes = -1;
                             res = NULL;
 #ifdef WITH_DEBUG