Random "Access violation writing location" error while calling ToFrozenDictionary after updating from .NET 8 to .NET 9

[rampaa]

Description

After updating my project from .NET 8 to .NET 9 my application started to crash randomly, I couldn't get any logs as to why it was crashing so I took a full dump when it crashed. It appears it's crashing after I call ToFrozenDictionary on a dictionary.

Here's the full error message:
Unhandled exception at 0x00007FFB075EB7A3 (System.Collections.Immutable.dll) in JL.exe.33024.dmp: 0xC0000005: Access violation writing location 0x0000044D37D1C080.

You can find the dump file in https://developercommunity.visualstudio.com/t/Random-Access-violation-writing-locatio/10820014

EDIT: I've found out I got an Unhandled exception at 0x00007FFAF8C3F18E (System.Private.CoreLib.dll) in JL.exe.15332.dmp: 0xC0000005: Access violation reading location 0x0000000041F9FA2A error a day before that resulted in a crash, added the dump file for it in the aforementioned link since it seems related.

Reproduction Steps

It appears to happen pretty rarely and randomly so I wasn't able to produce minimized reproduction steps. Hopefully the dump file can shed some light as to why it's happening.

Expected behavior

Calling ToFrozenDictionary does not produce an unhandled exception and does not crash the app

Actual behavior

Calling ToFrozenDictionary produces an unhandled exception and crashes the app

Regression?

Yes, I've never encountered this error before updating from .NET 8 to .NET 9

Known Workarounds

No response

Configuration

.NET 9, Windows 10 22H2 x64

Other information

No response

[dotnet-policy-service]

Tagging subscribers to this area: @mangod9
See info in area-owners.md if you want to be subscribed.

[jkotas]

This is duplicate of #108763 . It will be fixed in upcoming .NET 9 servicing update (#109548).

In the meantime, you can work around it by adding <PropertyGroup> <CETCompat>false</CETCompat> </PropertyGroup> to your .csproj. It will disable CET security feature that was enabled by default in .NET 9. The crash is caused by a bug in .NET support for CET security feature.

[jkotas]

Thank you reporting this issue and collecting the dumps

[rampaa]

This is probably a silly question but I don't own an Intel CPU, is it expected CETCompat to affect programs run under an AMD CPU?

[jkotas]

AMD processors support CET as well. For example, check https://windowsforum.com/threads/amd-releases-chipset-driver-with-cet-security-for-ryzen-cpus.344238/ for more information.