maliit-keyboard crashes with SIGSEGV in QString::fromUtf8 when processing surrounding_text Wayland event

[JefYamba]

Crash: SIGSEGV in QString::fromUtf8 during zwp_input_method_context_v1_surrounding_text

Environment

• maliit-keyboard version: 2.3.1-11.fc43
• maliit-framework version: 2.3.0-10.fc43
• Platform: Fedora 43, x86_64, KWin on Wayland
• Qt version: 5.x (libQt5Core.so.5)

Description

maliit-keyboard crashes with signal 11 (SIGSEGV) when processing a surrounding_text event from the Wayland compositor. The crash occurs inside QString::fromUtf8_helper when called from Maliit::Wayland::InputMethodContext::zwp_input_method_context_v1_surrounding_text. This indicates the const char* pointer passed from KWin is null or invalid and is not null-checked before being decoded.

Stack Trace

#0 QUtf8::convertToUnicodeE(QChar*, char const*, int)
#1 QUtf8::convertToUnicode(char const*, int)
#2 QString::fromUtf8_helper(char const*, int)
#3 Maliit::Wayland::InputMethodContext::zwp_input_method_context_v1_surrounding_text(QString const&, unsigned int, unsigned int)
#4 QtWayland::zwp_input_method_context_v1::handle_surrounding_text(...)
#5 ffi_call
#6 wl_closure_invoke

Expected Behavior

The input method should handle null or empty surrounding_text payloads gracefully without crashing.

Actual Behavior

Process segfaults and terminates.

Notes

• Not yet reliably reproducible
• Crash occurred during normal session usage
• Coredump available locally

[JefYamba]

This appears to be a duplicate of issue #262