Control: forcemerge 1147212 -1 Hey,
thanks for reporting the bug. Your reported issue is already reported in #1147212 and there is an ongoing proposed-update for Trixie ( see #1150067 ) to bring the fix to Trixie. The proposed fix is the backport of upstream commits e1fd647b and 172f8f2e. Best regards, hefee -- On Montag, 12. Oktober 2026 09:19 Phil Gees wrote: > Source: kwin > Version: 4:6.3.6-1 > Severity: important > Tags: patch > X-Debbugs-Cc: [email protected] > > Dear Maintainer, > > kwin_wayland segfaults when a display output is removed and then > re-enabled, e.g. via Power Management's "Turn off screen" idle action, > or DPMS screen-off followed by wake. All running applications (Firefox > in particular) crash along with the compositor, so the whole Wayland > session is lost. > > This is an exact match for upstream KDE bug 504959, already fixed > upstream by commit e1fd647b979df7f0bd10065932a614a2aa806e87 > ("wayland: Make ColorManagementOutputV1 handle output removal better", > Vlad Zahorodnii, 2025-05-30). The fix is included in Plasma 6.4, but > trixie ships 6.3.6, which is affected. > > Since wl_output removal is racy, a client can request > wp_color_manager_v1.get_output() after KWin has destroyed the > underlying handle but before the wl_output resource is gone. KWin then > dereferences a null pointer: > > Core was generated by `/usr/bin/kwin_wayland --wayland-fd 7 ...'. > Program terminated with signal SIGSEGV, Segmentation fault. > > #4 KWin::ColorManagementOutputV1::ColorManagementOutputV1 > (this=0x55951f72c7d0, client=<optimized out>, id=76, > version=1, output=0x0) > at ./src/wayland/colormanagement_v1.cpp:580 > #5 ffi_call () from libffi.so.8 > #8 wl_closure_invoke () from libwayland-server.so.0 > #10 wl_event_loop_dispatch () from libwayland-server.so.0 > #11 KWin::Display::dispatchEvents () at ./src/wayland/display.cpp:121 > > Reproducible: always, when the screen is turned off by the idle action > with Firefox running, then woken up. > > Environment: Debian trixie, kwin-wayland 4:6.3.6-1, Intel graphics > (i915), Mesa 25.0.7, Wayland session. > > Request: please backport the upstream fix (a small null-safety change > in src/wayland/colormanagement_v1.cpp/h) to the trixie package. > Upstream bug: https://bugs.kde.org/show_bug.cgi?id=504959 > Upstream fix: > https://invent.kde.org/plasma/kwin/-/commit/e1fd647b979df7f0bd10065932a614a > 2aa806e87 > > I can provide the full coredump on request. > > > -- System Information: > Debian Release: 13.7 > APT prefers stable-updates > APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, > 'stable-debug'), (500, 'stable') Architecture: amd64 (x86_64) > > Kernel: Linux 6.12.111+deb13-amd64 (SMP w/4 CPU threads; PREEMPT) > Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE > Locale: LANG=en_AU.UTF-8, LC_CTYPE=en_AU.UTF-8 (charmap=UTF-8), > LANGUAGE=en_AU:en Shell: /bin/sh linked to /usr/bin/dash > Init: systemd (via /run/systemd/system) > LSM: AppArmor: enabled
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