fix buffer overflow in parseEmoji (#2602)

Co-authored-by: Paweł <zneix@zneix.eu>
Co-authored-by: pajlada <rasmus.karlsson@pajlada.com>

CHANGELOG.md

@@ -87,6 +87,7 @@
 - Bugfix: Fix directory not opening when clicking "Open AppData Directory" setting button on macOS (#2531, #2537)
 - Bugfix: Fix quickswitcher not respecting order of tabs when filtering (#2519, #2561)
 - Bugfix: Fix GNOME not associating Chatterino's window with its desktop entry (#1863, #2587)
+- Bugfix: Fix buffer overflow in emoji parsing. (#2602)
 - Dev: Updated minimum required Qt framework version to 5.12. (#2210)
 - Dev: Migrated `Kraken::getUser` to Helix (#2260)
 - Dev: Migrated `TwitchAccount::(un)followUser` from Kraken to Helix and moved it to `Helix::(un)followUser`. (#2306)

src/providers/emoji/Emojis.cpp

@@ -24,7 +24,7 @@ namespace {
                     const rapidjson::Value &unparsedEmoji,
                     QString shortCode = QString())
     {
-        static uint unicodeBytes[4];
+        std::array<uint32_t, 7> unicodeBytes;
 
         struct {
             bool apple;
@@ -91,11 +91,12 @@ namespace {
 
         for (const QString &unicodeCharacter : unicodeCharacters)
         {
-            unicodeBytes[numUnicodeBytes++] =
+            unicodeBytes.at(numUnicodeBytes++) =
                 QString(unicodeCharacter).toUInt(nullptr, 16);
         }
 
-        emojiData->value = QString::fromUcs4(unicodeBytes, numUnicodeBytes);
+        emojiData->value =
+            QString::fromUcs4(unicodeBytes.data(), numUnicodeBytes);
     }
 
     // getToneNames takes a tones and returns their names in the same order