From d01f5777820c08cb3b48f5e9e3fbca5f0a988adb Mon Sep 17 00:00:00 2001
From: Theo Arends <11044339+arendst@users.noreply.github.com>
Date: Mon, 31 May 2021 18:34:51 +0200
Subject: [PATCH] Add log buffer max size check

---
 tasmota/support.ino | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tasmota/support.ino b/tasmota/support.ino
index 0054f8a01..8abb5d644 100644
--- a/tasmota/support.ino
+++ b/tasmota/support.ino
@@ -2307,6 +2307,9 @@ void AddLogData(uint32_t loglevel, const char* log_data) {
     Serial.printf("%s%s\r\n", mxtime, log_data);
   }
 
+  uint32_t log_data_len = strlen(log_data) + strlen(mxtime) + 4;  // 4 = log_buffer_pointer + '\1' + '\0'
+  if (log_data_len > LOG_BUFFER_SIZE) { return; }                 // log_data too big for buffer - discard logging
+
   uint32_t highest_loglevel = Settings.weblog_level;
   if (Settings.mqttlog_level > highest_loglevel) { highest_loglevel = Settings.mqttlog_level; }
   if (TasmotaGlobal.syslog_level > highest_loglevel) { highest_loglevel = TasmotaGlobal.syslog_level; }
@@ -2322,7 +2325,7 @@ void AddLogData(uint32_t loglevel, const char* log_data) {
       TasmotaGlobal.log_buffer_pointer++;  // Index 0 is not allowed as it is the end of char string
     }
     while (TasmotaGlobal.log_buffer_pointer == TasmotaGlobal.log_buffer[0] ||  // If log already holds the next index, remove it
-           strlen(TasmotaGlobal.log_buffer) + strlen(log_data) + strlen(mxtime) + 4 > LOG_BUFFER_SIZE)  // 4 = log_buffer_pointer + '\1' + '\0'
+           strlen(TasmotaGlobal.log_buffer) + log_data_len > LOG_BUFFER_SIZE)
     {
       char* it = TasmotaGlobal.log_buffer;
       it++;                                // Skip log_buffer_pointer