From c719d385ef376c848eb881565af23a8e304362d7 Mon Sep 17 00:00:00 2001
From: Oleg Moiseenko <807634+merlokk@users.noreply.github.com>
Date: Sat, 9 Feb 2019 23:38:09 +0200
Subject: [PATCH] fix endless loop (#782)

---
 armsrc/iso14443a.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c
index f5fcc91c..50160798 100644
--- a/armsrc/iso14443a.c
+++ b/armsrc/iso14443a.c
@@ -1955,7 +1955,7 @@ int iso14_apdu(uint8_t *cmd, uint16_t cmd_len, void *data, uint8_t *res) {
 		return 0; //DATA LINK ERROR
 	} else{
 		// S-Block WTX 
-		while((data_bytes[0] & 0xF2) == 0xF2) {
+		while(len && ((data_bytes[0] & 0xF2) == 0xF2)) {
 			uint32_t save_iso14a_timeout = iso14a_get_timeout();
 			// temporarily increase timeout
 			iso14a_set_timeout(MAX((data_bytes[1] & 0x3f) * save_iso14a_timeout, MAX_ISO14A_TIMEOUT));
@@ -1994,12 +1994,14 @@ int iso14_apdu(uint8_t *cmd, uint16_t cmd_len, void *data, uint8_t *res) {
 		
 	}
 	
-	// cut frame byte
-	len -= 1;
-	// memmove(data_bytes, data_bytes + 1, len);
-	for (int i = 0; i < len; i++)
-		data_bytes[i] = data_bytes[i + 1];
-	
+	if (len) {
+		// cut frame byte
+		len -= 1;
+		// memmove(data_bytes, data_bytes + 1, len);
+		for (int i = 0; i < len; i++)
+			data_bytes[i] = data_bytes[i + 1];
+	}
+		
 	return len;
 }
 
-- 
2.39.2