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iOS,macOS: Check viewType before creating a platform view - #191777

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cbracken:fix-unsafe-pv-string-handling
Aug 26, 2026
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iOS,macOS: Check viewType before creating a platform view#191777
cbracken merged 1 commit into
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cbracken:fix-unsafe-pv-string-handling

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@cbracken cbracken commented Aug 26, 2026

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When creating a platform view, both iOS and macOS converted the platform view viewType coming over the method channel into a string without checking whether the incoming value was actually (a) non-null and (b) a string.

In addition to this, macOS was manually converting the viewType value to an NSString, but the codec already returns an NSString whenever Dart sent one. Both embedders use FlutterStandardMethodCodec for this channel. FlutterStandardCodecHelper.cc null to kCFNull, which comes out of the channel as NSNull, and which doesn't respond to UTF8String at all, which causes a crash. Finally if the framework ever mistakenly passed an int, or a bool, or any other non-string type, we'd get a crash. If the parameters omit viewType altogether, it arrives as nil:

In any of these cases, we end up with a corrupt or nil viewType string:

  • On macOS, this triggers NSInvalidArgumentException from +stringWithUTF8String:
  • On iOS, we'd try to construct a std::string from NULL and segfault.

We now check that viewType is a string, which covers the nil, NSNull, and wrong-type cases. They now report a FlutterError instead of crashing.

Noticed while working on: #165904

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@cbracken
iOS,macOS: Check viewType before creating a platform view
d6c15a7 
When creating a platform view, both iOS and macOS converted the platform
view `viewType` coming over the method channel into a string without
checking whether the incoming value was actually (a) non-null and (b) a
string.

In addition to this, macOS was manually converting the `viewType` value
to an NSString, but the codec already returns an NSString whenever Dart
sent one. Both embedders use `FlutterStandardMethodCodec` for this channel.
`FlutterStandardCodecHelper.cc` null to `kCFNull`, which comes out of
the channel as `NSNull`, and which doesn't respond to `UTF8String` at
all, which causes a crash. Finally if the framework ever mistakenly
passed an int, or a bool, or any other non-string type, we'd get a crash.
If the parameters omit `viewType` altogether, it arrives as nil:

In any of these cases, we end up with a corrupt or nil viewType string:
  * On macOS, this triggers `NSInvalidArgumentException` from `+stringWithUTF8String:`
  * On iOS, we'd try to construct a `std::string` from NULL and segfault.

We now check that `viewType` is a string, which covers the nil,
`NSNull`, and wrong-type cases. They now report a `FlutterError` instead
of crashing.

Noticed while working on: flutter#165904
@cbracken
cbracken requested review from a team as code owners August 26, 2026 05:19
@flutter-dashboard flutter-dashboard Bot added the CICD Run CI/CD label Aug 26, 2026
@github-actions github-actions Bot added platform-ios iOS applications specifically engine flutter/engine related. See also e: labels. platform-macos Building on or for macOS specifically a: desktop Running on desktop team-ios Owned by iOS platform team team-macos Owned by the macOS platform team labels Aug 26, 2026
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Code Review

This pull request introduces validation to ensure that the 'viewType' argument is a string when creating platform views on iOS and macOS, returning a FlutterError if it is not. It also adds corresponding unit tests to verify this behavior. The review feedback highlights variable shadowing issues in both the iOS and macOS test files, where the block parameter 'result' shadows a local variable of the same name, and suggests renaming it to 'response' to prevent compiler warnings.

Comment thread engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformViewsTest.mm
Comment thread ...rc/flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewControllerTest.mm
@cbracken cbracken added the autosubmit Merge PR when tree becomes green via auto submit App label Aug 26, 2026
@cbracken
cbracken added this pull request to the merge queue Aug 26, 2026
Merged via the queue into flutter:master with commit 7455d8c Aug 26, 2026
29 of 30 checks passed
@cbracken
cbracken deleted the fix-unsafe-pv-string-handling branch August 26, 2026 13:24
@flutter-dashboard flutter-dashboard Bot removed the autosubmit Merge PR when tree becomes green via auto submit App label Aug 26, 2026
This was referenced Aug 27, 2026
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auto-submit Bot pushed a commit to flutter/packages that referenced this pull request Aug 28, 2026
@engine-flutter-autoroll
Roll Flutter from 15d8908addf6 to e8dca90ec9e0 (58 revisions) (#12660)
0bab416 
Roll Flutter from 15d8908addf6 to e8dca90ec9e0 (58 revisions)

flutter/flutter@15d8908...e8dca90

2026-08-27 [email protected] Terminate existing process before launching with devicectl (flutter/flutter#191885)
2026-08-27 [email protected] Roll Fuchsia Linux SDK from qjOQi-zAgu_tADorh... to dDxH8G5cDBP602eyG... (flutter/flutter#191889)
2026-08-27 [email protected] [flutter_tools] Verify native assets tree-shaking during linking (flutter/flutter#191637)
2026-08-27 [email protected] Denylists b-series powervr from vulkan (flutter/flutter#191808)
2026-08-27 [email protected] Handle linear and radial gradients in UberSDF (flutter/flutter#190874)
2026-08-27 [email protected] Roll Packages from 740f093 to bd3cbc1 (7 revisions) (flutter/flutter#191886)
2026-08-27 [email protected] Disable more Windows tests that have been causing CI flakes (flutter/flutter#191822)
2026-08-27 [email protected] Roll Skia from d32721369bd8 to 82e972ea84b1 (2 revisions) (flutter/flutter#191880)
2026-08-27 [email protected] Roll Skia from 3640b8edd16c to d32721369bd8 (10 revisions) (flutter/flutter#191858)
2026-08-27 [email protected] Revert: [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191863)
2026-08-27 [email protected] Roll Fuchsia Test Scripts from 0iCv10IlKfiilEBOU... to 6SXRz6wsA2Zm_rAqP... (flutter/flutter#191852)
2026-08-27 [email protected] Roll pub packages (flutter/flutter#191851)
2026-08-27 [email protected] Refactor FormField build wrappers (flutter/flutter#185795)
2026-08-27 [email protected] Make ScrollPhysics reactive by introducing shouldUpdate (flutter/flutter#189664)
2026-08-27 [email protected] macOS: Fix crash on out-of-bounds text input ranges (flutter/flutter#191780)
2026-08-27 [email protected] Add HCPP feature flag, and turn it on by default in beta/master (flutter/flutter#190623)
2026-08-27 [email protected] [tool] Migrate CleanCommand to modular dependency injection (flutter/flutter#190742)
2026-08-26 [email protected] Update triage docs for ecosystem and codelab changes (flutter/flutter#191809)
2026-08-26 [email protected] [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191824)
2026-08-26 [email protected] [UIScene] Migrate dev/benchmarks/complex_layout to UIScene lifecycle (flutter/flutter#191619)
2026-08-26 [email protected] Add SliverAppBar showOnScreen semantics test coverage (flutter/flutter#190410)
2026-08-26 [email protected] Add prompt_suggestion icon to list of RTL mirroring icons. (flutter/flutter#191741)
2026-08-26 [email protected] Remove bringup for batch 3 (flutter/flutter#191750)
2026-08-26 [email protected] Roll Skia from b5465d7b0b77 to 3640b8edd16c (6 revisions) (flutter/flutter#191835)
2026-08-26 [email protected] Uiscene migrate custom channels views (flutter/flutter#191817)
2026-08-26 [email protected] Support --[no-]adb-log-filtering CLI option (flutter/flutter#187252)
2026-08-26 [email protected] Roll Dart SDK from cb8a4e1a0fbb to cb4c39d067f3 (2 revisions) (flutter/flutter#191825)
2026-08-26 [email protected] Fix `Navigator.pushNamed<T>()` type checking (flutter/flutter#188148)
2026-08-26 [email protected] Handle the case where a window doesn't have a title set (flutter/flutter#191767)
2026-08-26 [email protected] [Android] Remove old `InputType` constructor from embedding (flutter/flutter#191244)
2026-08-26 [email protected] Roll Skia from 244a6a0f8f92 to b5465d7b0b77 (19 revisions) (flutter/flutter#191810)
2026-08-26 [email protected] Tolerate floating-point rounding in paintImage centerSlice assertion (flutter/flutter#185789)
2026-08-26 [email protected] Fixes translated bounded blurs (flutter/flutter#191615)
2026-08-26 [email protected] Roll Fuchsia Linux SDK from MstTWE1RDOT-RnrtH... to qjOQi-zAgu_tADorh... (flutter/flutter#191769)
2026-08-26 [email protected] Lerp HSVColor and HSLColor hue along the shortest arc (flutter/flutter#191186)
2026-08-26 [email protected] Fix enum instances comparison to use `equality ==` since dart has the correct behavior now (flutter/flutter#191537)
2026-08-26 [email protected] Switches windows to opengles 3 (flutter/flutter#191516)
2026-08-26 [email protected] Roll Dart SDK from 7739e8602bc1 to cb8a4e1a0fbb (1 revision) (flutter/flutter#191784)
2026-08-26 [email protected] iOS,macOS: Check viewType before creating a platform view (flutter/flutter#191777)
2026-08-26 [email protected] Revert: [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191793)
2026-08-26 [email protected] refactor(flutter_tools): clean up dead unreferenced declarations (flutter/flutter#191163)
2026-08-26 [email protected] Roll Fuchsia GN SDK from a87CbQSWEjkPUK1ZY... to ZsxUUK2SfA-TrNvb8... (flutter/flutter#191763)
2026-08-26 [email protected] [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191732)
2026-08-25 [email protected] Remove legacy gen_defaults analyze checks (flutter/flutter#191629)
2026-08-25 [email protected] Refactors `try` to avoid `unawaited_return_in_try_block` case (flutter/flutter#191129)
2026-08-25 [email protected] Roll Dart SDK from 8996935d3d0a to 7739e8602bc1 (1 revision) (flutter/flutter#191754)
...
victorsanni pushed a commit to victorsanni/packages that referenced this pull request Sep 9, 2026
@engine-flutter-autoroll @victorsanni
Roll Flutter from 15d8908addf6 to e8dca90ec9e0 (58 revisions) (flutte…
a4509c8 
…r#12660)

Roll Flutter from 15d8908addf6 to e8dca90ec9e0 (58 revisions)

flutter/flutter@15d8908...e8dca90

2026-08-27 [email protected] Terminate existing process before launching with devicectl (flutter/flutter#191885)
2026-08-27 [email protected] Roll Fuchsia Linux SDK from qjOQi-zAgu_tADorh... to dDxH8G5cDBP602eyG... (flutter/flutter#191889)
2026-08-27 [email protected] [flutter_tools] Verify native assets tree-shaking during linking (flutter/flutter#191637)
2026-08-27 [email protected] Denylists b-series powervr from vulkan (flutter/flutter#191808)
2026-08-27 [email protected] Handle linear and radial gradients in UberSDF (flutter/flutter#190874)
2026-08-27 [email protected] Roll Packages from 740f093 to bd3cbc1 (7 revisions) (flutter/flutter#191886)
2026-08-27 [email protected] Disable more Windows tests that have been causing CI flakes (flutter/flutter#191822)
2026-08-27 [email protected] Roll Skia from d32721369bd8 to 82e972ea84b1 (2 revisions) (flutter/flutter#191880)
2026-08-27 [email protected] Roll Skia from 3640b8edd16c to d32721369bd8 (10 revisions) (flutter/flutter#191858)
2026-08-27 [email protected] Revert: [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191863)
2026-08-27 [email protected] Roll Fuchsia Test Scripts from 0iCv10IlKfiilEBOU... to 6SXRz6wsA2Zm_rAqP... (flutter/flutter#191852)
2026-08-27 [email protected] Roll pub packages (flutter/flutter#191851)
2026-08-27 [email protected] Refactor FormField build wrappers (flutter/flutter#185795)
2026-08-27 [email protected] Make ScrollPhysics reactive by introducing shouldUpdate (flutter/flutter#189664)
2026-08-27 [email protected] macOS: Fix crash on out-of-bounds text input ranges (flutter/flutter#191780)
2026-08-27 [email protected] Add HCPP feature flag, and turn it on by default in beta/master (flutter/flutter#190623)
2026-08-27 [email protected] [tool] Migrate CleanCommand to modular dependency injection (flutter/flutter#190742)
2026-08-26 [email protected] Update triage docs for ecosystem and codelab changes (flutter/flutter#191809)
2026-08-26 [email protected] [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191824)
2026-08-26 [email protected] [UIScene] Migrate dev/benchmarks/complex_layout to UIScene lifecycle (flutter/flutter#191619)
2026-08-26 [email protected] Add SliverAppBar showOnScreen semantics test coverage (flutter/flutter#190410)
2026-08-26 [email protected] Add prompt_suggestion icon to list of RTL mirroring icons. (flutter/flutter#191741)
2026-08-26 [email protected] Remove bringup for batch 3 (flutter/flutter#191750)
2026-08-26 [email protected] Roll Skia from b5465d7b0b77 to 3640b8edd16c (6 revisions) (flutter/flutter#191835)
2026-08-26 [email protected] Uiscene migrate custom channels views (flutter/flutter#191817)
2026-08-26 [email protected] Support --[no-]adb-log-filtering CLI option (flutter/flutter#187252)
2026-08-26 [email protected] Roll Dart SDK from cb8a4e1a0fbb to cb4c39d067f3 (2 revisions) (flutter/flutter#191825)
2026-08-26 [email protected] Fix `Navigator.pushNamed<T>()` type checking (flutter/flutter#188148)
2026-08-26 [email protected] Handle the case where a window doesn't have a title set (flutter/flutter#191767)
2026-08-26 [email protected] [Android] Remove old `InputType` constructor from embedding (flutter/flutter#191244)
2026-08-26 [email protected] Roll Skia from 244a6a0f8f92 to b5465d7b0b77 (19 revisions) (flutter/flutter#191810)
2026-08-26 [email protected] Tolerate floating-point rounding in paintImage centerSlice assertion (flutter/flutter#185789)
2026-08-26 [email protected] Fixes translated bounded blurs (flutter/flutter#191615)
2026-08-26 [email protected] Roll Fuchsia Linux SDK from MstTWE1RDOT-RnrtH... to qjOQi-zAgu_tADorh... (flutter/flutter#191769)
2026-08-26 [email protected] Lerp HSVColor and HSLColor hue along the shortest arc (flutter/flutter#191186)
2026-08-26 [email protected] Fix enum instances comparison to use `equality ==` since dart has the correct behavior now (flutter/flutter#191537)
2026-08-26 [email protected] Switches windows to opengles 3 (flutter/flutter#191516)
2026-08-26 [email protected] Roll Dart SDK from 7739e8602bc1 to cb8a4e1a0fbb (1 revision) (flutter/flutter#191784)
2026-08-26 [email protected] iOS,macOS: Check viewType before creating a platform view (flutter/flutter#191777)
2026-08-26 [email protected] Revert: [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191793)
2026-08-26 [email protected] refactor(flutter_tools): clean up dead unreferenced declarations (flutter/flutter#191163)
2026-08-26 [email protected] Roll Fuchsia GN SDK from a87CbQSWEjkPUK1ZY... to ZsxUUK2SfA-TrNvb8... (flutter/flutter#191763)
2026-08-26 [email protected] [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191732)
2026-08-25 [email protected] Remove legacy gen_defaults analyze checks (flutter/flutter#191629)
2026-08-25 [email protected] Refactors `try` to avoid `unawaited_return_in_try_block` case (flutter/flutter#191129)
2026-08-25 [email protected] Roll Dart SDK from 8996935d3d0a to 7739e8602bc1 (1 revision) (flutter/flutter#191754)
...
victorsanni pushed a commit to victorsanni/packages that referenced this pull request Sep 9, 2026
@engine-flutter-autoroll @victorsanni
Roll Flutter from 15d8908addf6 to e8dca90ec9e0 (58 revisions) (flutte…
675e8a4 
…r#12660)

Roll Flutter from 15d8908addf6 to e8dca90ec9e0 (58 revisions)

flutter/flutter@15d8908...e8dca90

2026-08-27 [email protected] Terminate existing process before launching with devicectl (flutter/flutter#191885)
2026-08-27 [email protected] Roll Fuchsia Linux SDK from qjOQi-zAgu_tADorh... to dDxH8G5cDBP602eyG... (flutter/flutter#191889)
2026-08-27 [email protected] [flutter_tools] Verify native assets tree-shaking during linking (flutter/flutter#191637)
2026-08-27 [email protected] Denylists b-series powervr from vulkan (flutter/flutter#191808)
2026-08-27 [email protected] Handle linear and radial gradients in UberSDF (flutter/flutter#190874)
2026-08-27 [email protected] Roll Packages from 740f093 to bd3cbc1 (7 revisions) (flutter/flutter#191886)
2026-08-27 [email protected] Disable more Windows tests that have been causing CI flakes (flutter/flutter#191822)
2026-08-27 [email protected] Roll Skia from d32721369bd8 to 82e972ea84b1 (2 revisions) (flutter/flutter#191880)
2026-08-27 [email protected] Roll Skia from 3640b8edd16c to d32721369bd8 (10 revisions) (flutter/flutter#191858)
2026-08-27 [email protected] Revert: [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191863)
2026-08-27 [email protected] Roll Fuchsia Test Scripts from 0iCv10IlKfiilEBOU... to 6SXRz6wsA2Zm_rAqP... (flutter/flutter#191852)
2026-08-27 [email protected] Roll pub packages (flutter/flutter#191851)
2026-08-27 [email protected] Refactor FormField build wrappers (flutter/flutter#185795)
2026-08-27 [email protected] Make ScrollPhysics reactive by introducing shouldUpdate (flutter/flutter#189664)
2026-08-27 [email protected] macOS: Fix crash on out-of-bounds text input ranges (flutter/flutter#191780)
2026-08-27 [email protected] Add HCPP feature flag, and turn it on by default in beta/master (flutter/flutter#190623)
2026-08-27 [email protected] [tool] Migrate CleanCommand to modular dependency injection (flutter/flutter#190742)
2026-08-26 [email protected] Update triage docs for ecosystem and codelab changes (flutter/flutter#191809)
2026-08-26 [email protected] [AGP 9] Update remaining tests to AGP 9 (flutter/flutter#191824)
2026-08-26 [email protected] [UIScene] Migrate dev/benchmarks/complex_layout to UIScene lifecycle (flutter/flutter#191619)
2026-08-26 [email protected] Add SliverAppBar showOnScreen semantics test coverage (flutter/flutter#190410)
2026-08-26 [email protected] Add prompt_suggestion icon to list of RTL mirroring icons. (flutter/flutter#191741)
2026-08-26 [email protected] Remove bringup for batch 3 (flutter/flutter#191750)
2026-08-26 [email protected] Roll Skia from b5465d7b0b77 to 3640b8edd16c (6 revisions) (flutter/flutter#191835)
2026-08-26 [email protected] Uiscene migrate custom channels views (flutter/flutter#191817)
2026-08-26 [email protected] Support --[no-]adb-log-filtering CLI option (flutter/flutter#187252)
2026-08-26 [email protected] Roll Dart SDK from cb8a4e1a0fbb to cb4c39d067f3 (2 revisions) (flutter/flutter#191825)
2026-08-26 [email protected] Fix `Navigator.pushNamed<T>()` type checking (flutter/flutter#188148)
2026-08-26 [email protected] Handle the case where a window doesn't have a title set (flutter/flutter#191767)
2026-08-26 [email protected] [Android] Remove old `InputType` constructor from embedding (flutter/flutter#191244)
2026-08-26 [email protected] Roll Skia from 244a6a0f8f92 to b5465d7b0b77 (19 revisions) (flutter/flutter#191810)
2026-08-26 [email protected] Tolerate floating-point rounding in paintImage centerSlice assertion (flutter/flutter#185789)
2026-08-26 [email protected] Fixes translated bounded blurs (flutter/flutter#191615)
2026-08-26 [email protected] Roll Fuchsia Linux SDK from MstTWE1RDOT-RnrtH... to qjOQi-zAgu_tADorh... (flutter/flutter#191769)
2026-08-26 [email protected] Lerp HSVColor and HSLColor hue along the shortest arc (flutter/flutter#191186)
2026-08-26 [email protected] Fix enum instances comparison to use `equality ==` since dart has the correct behavior now (flutter/flutter#191537)
2026-08-26 [email protected] Switches windows to opengles 3 (flutter/flutter#191516)
2026-08-26 [email protected] Roll Dart SDK from 7739e8602bc1 to cb8a4e1a0fbb (1 revision) (flutter/flutter#191784)
2026-08-26 [email protected] iOS,macOS: Check viewType before creating a platform view (flutter/flutter#191777)
2026-08-26 [email protected] Revert: [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191793)
2026-08-26 [email protected] refactor(flutter_tools): clean up dead unreferenced declarations (flutter/flutter#191163)
2026-08-26 [email protected] Roll Fuchsia GN SDK from a87CbQSWEjkPUK1ZY... to ZsxUUK2SfA-TrNvb8... (flutter/flutter#191763)
2026-08-26 [email protected] [tool_tests] Remove bringup from Windows tool_tests_commands_2_2 (flutter/flutter#191732)
2026-08-25 [email protected] Remove legacy gen_defaults analyze checks (flutter/flutter#191629)
2026-08-25 [email protected] Refactors `try` to avoid `unawaited_return_in_try_block` case (flutter/flutter#191129)
2026-08-25 [email protected] Roll Dart SDK from 8996935d3d0a to 7739e8602bc1 (1 revision) (flutter/flutter#191754)
...
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@LongCatIsLooong LongCatIsLooong LongCatIsLooong approved these changes
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a: desktop Running on desktop CICD Run CI/CD engine flutter/engine related. See also e: labels. platform-ios iOS applications specifically platform-macos Building on or for macOS specifically team-ios Owned by iOS platform team team-macos Owned by the macOS platform team

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