From a647ceda23acfb5ec6e40e93d41b7e282256a296 Mon Sep 17 00:00:00 2001
From: Philippe Teuwen <phil@teuwen.org>
Date: Tue, 6 Oct 2020 15:41:57 +0200
Subject: [PATCH] fix buffer underflow read

---
 client/src/ui.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/client/src/ui.c b/client/src/ui.c
index ecc0cb94e..26759cc4d 100644
--- a/client/src/ui.c
+++ b/client/src/ui.c
@@ -356,7 +356,7 @@ static void fPrintAndLog(FILE *stream, const char *fmt, ...) {
     va_start(argptr, fmt);
     vsnprintf(buffer, sizeof(buffer), fmt, argptr);
     va_end(argptr);
-    if (buffer[strlen(buffer) - 1] == NOLF[0]) {
+    if (strlen(buffer) > 0 && buffer[strlen(buffer) - 1] == NOLF[0]) {
         linefeed = false;
         buffer[strlen(buffer) - 1] = 0;
     }