Hyprland crashes when reloading keyboard config

[hakanersu]

Hyprland version

0.56.2

Is this a regression?

Don't know

What's the bug?

I'm using lan-mouse between my mac and linux. Hyprland crashes randomly in around 1h mark after restart.

I'm no where near to explain the real cause and I know that there are checkboxes that suggest I should be writing this myself but the rest of the explanation is done by AI. I get help from AI and applied a fix myself and so far I'm not experiencing crashes for around 3-4h.

---

Hyprland crashes with SIGABRT. I symbolized the coredump with gdb + debuginfod and it's a null-pointer dereference in
CKeybindManager::updateXKBTranslationState() (src/managers/KeybindManager.cpp):

xkb_context_unref(PCONTEXT);
m_xkbTranslationState = xkb_state_new(PKEYMAP);   // <- PKEYMAP is NULL here
xkb_keymap_unref(PKEYMAP);

Looking at the function, there's already a null-check on the first keymap build attempt, with a fallback to default rules if it
fails:

if (!PKEYMAP) {
    ...
    memset(&rules, 0, sizeof(rules));
    PKEYMAP = xkb_keymap_new_from_names2(PCONTEXT, &rules, XKB_KEYMAP_FORMAT_TEXT_V2, XKB_KEYMAP_COMPILE_NO_FLAGS);
}

but the fallback's result is never checked before being passed to xkb_state_new(). In my crash, the fallback apparently failed too,
leaving PKEYMAP null and crashing on the null dereference inside libxkbcommon's xkb_keymap_ref.

Backtrace (symbolized):

#7  xkb_keymap_ref (keymap=0x0) at libxkbcommon/src/keymap.c:26
    assert(keymap->refcnt > 0);
#8  xkb_state_new (keymap=0x0) at libxkbcommon/src/state.c:883
    state->keymap = xkb_keymap_ref(keymap);
#9  CKeybindManager::updateXKBTranslationState() at KeybindManager.cpp:332
    m_xkbTranslationState = xkb_state_new(PKEYMAP);
#10 Config::Supplementary::CPropRefresher::refreshProp(bool)

Triggered from a live config property refresh, not startup.

My keyboard config (via Omarchy's Lua config layer, wrapping hyprland.conf):

kb_layout = "us,tr"
kb_options = "compose:caps,shift:both_capslock_cancel,grp:alts_toggle"

Suspected trigger: lan-mouse creates/destroys input-capture (EIS) sessions rapidly every time the mouse crosses the screen edge during a KVM handoff. I've also seen a separate, related-looking crash a few times where Hyprland aborts inside its input-capture protocol code
(CInputCaptureResourceC2 / onCreateSession) with an assertion failing inside libeis.so.1 — possibly the same underlying race under rapid session churn, possibly a second issue.

The fix I applied locally: a null check right after the fallback, before it's used:

xkb_context_unref(PCONTEXT);

if (!PKEYMAP) {
    Log::logger->log(Log::ERR, "[XKBTranslationState] Fallback keymap creation failed as well, keeping previous translation state");
    return;
}

m_xkbTranslationState = xkb_state_new(PKEYMAP);
xkb_keymap_unref(PKEYMAP);

Reproduction steps

Its hard to test but you can use lan-mouse and connect another computer. Test it a while because the crashes are very random.

Attachments

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• I wrote this request with my own hands, my own keyboard, and in my own words.