Debug Tools: fixed DebugTextEncoding() potentially reading out of bounds if provided a trailing truncated UTF-8 sequence.

docs/CHANGELOG.txt

@@ -64,6 +64,8 @@ Other Changes:
   triggered by some widgets e.g. Checkbox(), Selectable() and many others, which
   cleared ActiveId at the same time as editing. (#9028)
   Note that IsItemDeactivatedAfterEdit() was not affected, only IsItemEdited).
+- Debug Tools: fixed DebugTextEncoding() potentially reading out of bounds
+  if provided a trailing truncated UTF-8 sequence.
 - Backends:
   - GLFW: fixed building on Linux platforms where Wayland headers
     are not available. (#9024, #8969, #8921, #8920) [@jagot]
@@ -78,7 +80,6 @@ Other Changes:
     (note: examples application were not updated yet)
   - Win32: Revert 1.92.4 change of comparing dwPacketNumber, which prevents
     refreshing accurate gamepad info after focus-out + io.ClearInputKeys(). (#8556)
-
 - Examples:
   - GLFW+WebGPU: removed unnecessary ImGui_ImplWGPU_InvalidateDeviceObjects() call
     during surface resize. (#8381)

imgui.cpp

@@ -1642,14 +1642,15 @@ void ImGuiIO::AddInputCharacterUTF16(ImWchar16 c)
     AddInputCharacter((unsigned)cp);
 }
 
-void ImGuiIO::AddInputCharactersUTF8(const char* utf8_chars)
+void ImGuiIO::AddInputCharactersUTF8(const char* str)
 {
     if (!AppAcceptingEvents)
         return;
-    while (*utf8_chars != 0)
+    const char* str_end = str + strlen(str);
+    while (*str != 0)
     {
         unsigned int c = 0;
-        utf8_chars += ImTextCharFromUtf8(&c, utf8_chars, NULL);
+        str += ImTextCharFromUtf8(&c, str, str_end);
         AddInputCharacter(c);
     }
 }
@@ -2502,6 +2503,7 @@ int ImTextCharFromUtf8(unsigned int* out_char, const char* in_text, const char*
     int len = lengths[*(const unsigned char*)in_text >> 3];
     int wanted = len + (len ? 0 : 1);
 
+    // IMPORTANT: if in_text_end == NULL it assume we have enough space!
     if (in_text_end == NULL)
         in_text_end = in_text + wanted; // Max length, nulls will be taken into account.
 
@@ -15998,10 +16000,11 @@ void ImGui::DebugTextEncoding(const char* str)
     TableSetupColumn("Glyph");
     TableSetupColumn("Codepoint");
     TableHeadersRow();
+    const char* str_end = str + strlen(str); // As we may receive malformed UTF-8, pass an explicit end instead of relying on ImTextCharFromUtf8() assuming enough space.
     for (const char* p = str; *p != 0; )
     {
         unsigned int c;
-        const int c_utf8_len = ImTextCharFromUtf8(&c, p, NULL);
+        const int c_utf8_len = ImTextCharFromUtf8(&c, p, str_end);
         TableNextColumn();
         Text("%d", (int)(p - str));
         TableNextColumn();

imgui_draw.cpp

@@ -5023,7 +5023,9 @@ const ImWchar*  ImFontAtlas::GetGlyphRangesVietnamese()
 
 void ImFontGlyphRangesBuilder::AddText(const char* text, const char* text_end)
 {
-    while (text_end ? (text < text_end) : *text)
+    if (text_end == NULL)
+        text_end = text + strlen(text);
+    while (text < text_end)
     {
         unsigned int c = 0;
         int c_len = ImTextCharFromUtf8(&c, text, text_end);

imgui_widgets.cpp

@@ -5151,12 +5151,13 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
             {
                 // Filter pasted buffer
                 const int clipboard_len = (int)ImStrlen(clipboard);
+                const char* clipboard_end = clipboard + clipboard_len;
                 ImVector<char> clipboard_filtered;
                 clipboard_filtered.reserve(clipboard_len + 1);
                 for (const char* s = clipboard; *s != 0; )
                 {
                     unsigned int c;
-                    int in_len = ImTextCharFromUtf8(&c, s, NULL);
+                    int in_len = ImTextCharFromUtf8(&c, s, clipboard_end);
                     s += in_len;
                     if (!InputTextFilterCharacter(&g, &c, flags, callback, callback_user_data, true))
                         continue;