From e2d3800fc36700ad21bb9525411f63e33636cd58 Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Wed, 19 Apr 2023 15:34:35 +0200
Subject: [PATCH] woraround for spurious crash in serializePalettes

the root cause of the crash is not really clear, as the problem seems to occur randomly, mosr frequent with fresh installations.
This workaround prevents the array bounds violation, by re-using the last valid  gGradientPalettes entry.
---
 wled00/json.cpp | 13 +++++++++++--
 wled00/wled.h   |  2 +-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/wled00/json.cpp b/wled00/json.cpp
index 44c2d280..ea6856d6 100644
--- a/wled00/json.cpp
+++ b/wled00/json.cpp
@@ -1072,7 +1072,7 @@ void setPaletteColors(JsonArray json, byte* tcp)
 
 void serializePalettes(JsonObject root, AsyncWebServerRequest* request)
 {
-  byte tcp[72];
+  byte tcp[72 +4] = { 255 }; // WLEDMM bugfix - use extra element as "stop" marker (=255) for setPaletteColors(). And no, I won't cry over 4 bytes wasted ;-)
   #ifdef ESP8266
   int itemPerPage = 5;
   #else
@@ -1173,7 +1173,16 @@ void serializePalettes(JsonObject root, AsyncWebServerRequest* request)
         if (i>=palettesCount) {
           setPaletteColors(curPalette, strip.customPalettes[i - palettesCount]);
         } else {
-          memcpy_P(tcp, (byte*)pgm_read_dword(&(gGradientPalettes[i - 13])), 72);
+          // WLEDMM workaround for palettes index overflow at i=74 -> gGradientPalettes index=61 out of bounds.
+          int palIndex = i-13;
+          constexpr int palMax = sizeof(gGradientPalettes)/sizeof(gGradientPalettes[0]) -1;
+          if ((palIndex < 0) || (palIndex > palMax)) { 
+            DEBUG_PRINTF("WARNING gGradientPalettes[%d] is out of bounds! max=%d. (json.cpp)\n", palIndex, palMax);
+            palIndex = palMax;  // use last valid array item
+          }
+          memset(tcp, 255, sizeof(tcp));  // WLEDMM pre-fill buffer with dummy values, to avoid array overrun in setPaletteColors in case of "unterminated" palette entry
+          // WLEDMM end
+          memcpy_P(tcp, (byte*)pgm_read_dword(&(gGradientPalettes[palIndex])), 72);
           setPaletteColors(curPalette, tcp);
         }
         }
diff --git a/wled00/wled.h b/wled00/wled.h
index 25016a98..2dd23031 100644
--- a/wled00/wled.h
+++ b/wled00/wled.h
@@ -8,7 +8,7 @@
  */
 
 // version code in format yymmddb (b = daily build)
-#define VERSION 2304170
+#define VERSION 2304190
 
 //uncomment this if you have a "my_config.h" file you'd like to use
 //#define WLED_USE_MY_CONFIG