Fix crash when closing a window with `Alt+F4` in multi-win Flutter on Windows #161375

hbatagelo · 2025-01-09T12:57:16Z

As mentioned in #158450, the crash occurs because a destroyed object may be accessed if the window and view have already been destroyed by the time KeyEventCallback is called. This issue is not limited to the Alt+F4 system key; it may also occur if the window is closed using other key presses, such as pressing Enter after navigating to a dialog's "Close" button.

This PR proposes a fix that checks whether the view ID is still valid when the callback is invoked. If the view is invalid, the event is skipped for that view.

A unit test has been added to assert that the KeyEventCallback is invoked when the associated view is valid and not invoked when the view is destroyed.

Pre-launch Checklist

I read the Contributor Guide and followed the process outlined there for submitting PRs.
I read the Tree Hygiene wiki page, which explains my responsibilities.
I read and followed the Flutter Style Guide, including Features we expect every widget to implement.
I signed the CLA.
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is test-exempt.
I followed the breaking change policy and added Data Driven Fixes where supported.
All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel on Discord.

dkwingsmt · 2025-01-09T19:59:54Z

Thank you for working on this. While the current fix works, I doubt if it's the best way to check views in this method, because the entire block doesn't seem to reference views at all:

        if (!handled) {
          engine_->text_input_plugin()->KeyboardHook(
              key, scancode, action, character, extended, was_down);
        }
        callback(handled);

It doesn't mention this either (and we can probably make it clearer by replacing = with explicit captures.

I suspect the crash happens inside callback, which is another callback nesting another callback. What I want to say is, I think it might be better to find out where actually in these callbacks that a view is used, and guard that usage instead. What do you think?

… only

hbatagelo · 2025-01-13T13:19:51Z

Thanks for the review. I've replaced the capture default = with explicit captures and moved the if (engine->view(view_id)) check to guard callback only, as this is where the view is actually used.

I couldn't move the check further into the callback because the callback is a lambda expression created in KeyboardManager, which doesn't keep a reference to the engine. The lambda ultimately calls a KeyboardManager member function as the final nested callback. KeyboardManager is owned by the FlutterWindow and may have already been destroyed by the time the callback is called.

dkwingsmt · 2025-01-13T20:58:55Z

I see, yeah it's definitely some oversight. I'll see if I can find a more elegant way later. But this one is a good fix. Thanks for you investigation!

dkwingsmt

LGTM

…utter on Windows (flutter/flutter#161375)

Roll Flutter from 72db8f6 to 40c2b86 (33 revisions) flutter/flutter@72db8f6...40c2b86 2025-01-14 [email protected] update changelog for 3.27.2 release (flutter/flutter#161569) 2025-01-14 [email protected] Fix `showLicensePage` does not inherit ambient `Theme` (flutter/flutter#161599) 2025-01-14 [email protected] Added special case for fat width arcs (flutter/flutter#161255) 2025-01-14 [email protected] Replace `fetch `with `gclient sync`. (flutter/flutter#161565) 2025-01-14 [email protected] Roll Packages from 3c3bc68 to d1fd623 (4 revisions) (flutter/flutter#161597) 2025-01-14 [email protected] Remove unused method (flutter/flutter#161572) 2025-01-14 [email protected] Fix crash when closing a window with `Alt+F4` in multi-win Flutter on Windows (flutter/flutter#161375) 2025-01-14 [email protected] Update InputDecoration.border documentation (flutter/flutter#161415) 2025-01-14 [email protected] [Web] Allow specifying the strategy on when to use <img> element to display images (flutter/flutter#159917) 2025-01-14 [email protected] Roll Dart to Version 3.7.0-323.0.dev (flutter/flutter#161567) 2025-01-14 [email protected] Use wildcards (flutter/flutter#161548) 2025-01-14 [email protected] Autocomplete Options Width (flutter/flutter#143249) 2025-01-13 [email protected] Move the analyzer_benchmark to Mac arm64 devicelab bots (flutter/flutter#161405) 2025-01-13 [email protected] Remove references to `cirrus`, mostly in doc comments. (flutter/flutter#161529) 2025-01-13 [email protected] Fix paths when running clang-tidy on git diffs (flutter/flutter#161496) 2025-01-13 [email protected] [web:a11y] treat empty tappables as buttons (flutter/flutter#161360) 2025-01-13 [email protected] Add route settings to CupertinoSheetRoute (flutter/flutter#161528) 2025-01-13 [email protected] Copy `linux_host_engine` as `linux_host_engine_test`, removing `archives: [...]`. (flutter/flutter#161532) 2025-01-13 [email protected] Remove last two references to Cirrus CI. (flutter/flutter#161530) 2025-01-13 [email protected] Mark `Mac_mokey microbenchmarks` as flakey (flutter/flutter#161550) 2025-01-13 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Match CupertinoPageTransitionsBuilder animation duration to CupertinoPageRoute (#160241)" (flutter/flutter#161555) 2025-01-13 [email protected] Add validator execution times to `flutter doctor --verbose` (flutter/flutter#158124) 2025-01-13 [email protected] Explain more specifically how to use `flutter drive`/what it does (flutter/flutter#161450) 2025-01-13 [email protected] Fixed repeated strings for incompatible Gradle or AGP version in `create` command (flutter/flutter#161223) 2025-01-13 [email protected] Remove `WEB_SHARD_COUNT`, which no longer exists post-Cirrus. (flutter/flutter#161527) 2025-01-13 [email protected] [Impeller] Update guidance on prebuilt artifacts. (flutter/flutter#161251) 2025-01-13 [email protected] Migrate DisplayList unit tests to DL/Impeller geometry classes (flutter/flutter#161453) 2025-01-13 [email protected] Context menu button callback docs clarification (flutter/flutter#161451) 2025-01-13 [email protected] Match CupertinoPageTransitionsBuilder animation duration to CupertinoPageRoute (flutter/flutter#160241) 2025-01-13 [email protected] Udpate documentation on the third_party directories (flutter/flutter#161407) 2025-01-13 [email protected] Propagate environment variables when `flutter drive` is invoked. (flutter/flutter#161452) 2025-01-13 [email protected] Convert base application name handling to kotlin source (start of FGP kt conversion) (flutter/flutter#155963) 2025-01-13 [email protected] [Impeller] remove API 30 restriction for SurfaceControl testing. (flutter/flutter#161438) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: ...

… Windows (flutter#161375) Reopened from flutter/engine#56501. Fixes [flutter#158450](flutter#158450). As mentioned in [flutter#158450](flutter#158450), the crash occurs because a destroyed object may be accessed if the window and view have already been destroyed by the time `KeyEventCallback` is called. This issue is not limited to the `Alt+F4` system key; it may also occur if the window is closed using other key presses, such as pressing `Enter` after navigating to a dialog's "Close" button. This PR proposes a fix that checks whether the view ID is still valid when the callback is invoked. If the view is invalid, the event is skipped for that view. A unit test has been added to assert that the `KeyEventCallback` is invoked when the associated view is valid and not invoked when the view is destroyed. ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [ ] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing. If you need help, consider asking for advice on the #hackers-new channel on [Discord].  [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

…utter on Windows (flutter/flutter#161375)

Roll Flutter from 72db8f6 to 40c2b86 (33 revisions) flutter/flutter@72db8f6...40c2b86 2025-01-14 [email protected] update changelog for 3.27.2 release (flutter/flutter#161569) 2025-01-14 [email protected] Fix `showLicensePage` does not inherit ambient `Theme` (flutter/flutter#161599) 2025-01-14 [email protected] Added special case for fat width arcs (flutter/flutter#161255) 2025-01-14 [email protected] Replace `fetch `with `gclient sync`. (flutter/flutter#161565) 2025-01-14 [email protected] Roll Packages from 3c3bc68 to d1fd623 (4 revisions) (flutter/flutter#161597) 2025-01-14 [email protected] Remove unused method (flutter/flutter#161572) 2025-01-14 [email protected] Fix crash when closing a window with `Alt+F4` in multi-win Flutter on Windows (flutter/flutter#161375) 2025-01-14 [email protected] Update InputDecoration.border documentation (flutter/flutter#161415) 2025-01-14 [email protected] [Web] Allow specifying the strategy on when to use <img> element to display images (flutter/flutter#159917) 2025-01-14 [email protected] Roll Dart to Version 3.7.0-323.0.dev (flutter/flutter#161567) 2025-01-14 [email protected] Use wildcards (flutter/flutter#161548) 2025-01-14 [email protected] Autocomplete Options Width (flutter/flutter#143249) 2025-01-13 [email protected] Move the analyzer_benchmark to Mac arm64 devicelab bots (flutter/flutter#161405) 2025-01-13 [email protected] Remove references to `cirrus`, mostly in doc comments. (flutter/flutter#161529) 2025-01-13 [email protected] Fix paths when running clang-tidy on git diffs (flutter/flutter#161496) 2025-01-13 [email protected] [web:a11y] treat empty tappables as buttons (flutter/flutter#161360) 2025-01-13 [email protected] Add route settings to CupertinoSheetRoute (flutter/flutter#161528) 2025-01-13 [email protected] Copy `linux_host_engine` as `linux_host_engine_test`, removing `archives: [...]`. (flutter/flutter#161532) 2025-01-13 [email protected] Remove last two references to Cirrus CI. (flutter/flutter#161530) 2025-01-13 [email protected] Mark `Mac_mokey microbenchmarks` as flakey (flutter/flutter#161550) 2025-01-13 98614782+auto-submit[bot]@users.noreply.github.com Reverts "Match CupertinoPageTransitionsBuilder animation duration to CupertinoPageRoute (#160241)" (flutter/flutter#161555) 2025-01-13 [email protected] Add validator execution times to `flutter doctor --verbose` (flutter/flutter#158124) 2025-01-13 [email protected] Explain more specifically how to use `flutter drive`/what it does (flutter/flutter#161450) 2025-01-13 [email protected] Fixed repeated strings for incompatible Gradle or AGP version in `create` command (flutter/flutter#161223) 2025-01-13 [email protected] Remove `WEB_SHARD_COUNT`, which no longer exists post-Cirrus. (flutter/flutter#161527) 2025-01-13 [email protected] [Impeller] Update guidance on prebuilt artifacts. (flutter/flutter#161251) 2025-01-13 [email protected] Migrate DisplayList unit tests to DL/Impeller geometry classes (flutter/flutter#161453) 2025-01-13 [email protected] Context menu button callback docs clarification (flutter/flutter#161451) 2025-01-13 [email protected] Match CupertinoPageTransitionsBuilder animation duration to CupertinoPageRoute (flutter/flutter#160241) 2025-01-13 [email protected] Udpate documentation on the third_party directories (flutter/flutter#161407) 2025-01-13 [email protected] Propagate environment variables when `flutter drive` is invoked. (flutter/flutter#161452) 2025-01-13 [email protected] Convert base application name handling to kotlin source (start of FGP kt conversion) (flutter/flutter#155963) 2025-01-13 [email protected] [Impeller] remove API 30 restriction for SurfaceControl testing. (flutter/flutter#161438) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: ...

Check if the view is valid when the key event callback is called

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hbatagelo added platform-windows Building on or for Windows specifically a: desktop Running on desktop labels Jan 9, 2025

github-actions bot added the engine flutter/engine related. See also e: labels. label Jan 9, 2025

hbatagelo requested review from dkwingsmt and loic-sharma January 9, 2025 15:36

hbatagelo added 2 commits January 13, 2025 10:17

Add explicit captures and move view check to guard callback execution…

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Merge branch 'master' into fix-multi-win-crash-on-close

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dkwingsmt approved these changes Jan 13, 2025

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Merged via the queue into flutter:master with commit f2c15f9 Jan 14, 2025
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Fix crash when closing a window with `Alt+F4` in multi-win Flutter on Windows #161375

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