[Win11] [Bug] [ConcurrentBag regression in .Net 9] System.AccessViolationException: 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'

[drweb86]

Steps:

1. Create new .Net 9 project and put code in Visual Studio 2022

using System.Collections.Concurrent;

var breakingBadHoleInTheBag = new ConcurrentBag<ConcurrentBagItem>();

int tries = 500000;
while (tries-- > 0)
{
    breakingBadHoleInTheBag.SingleOrDefault(x => x == (object)breakingBadHoleInTheBag);
    breakingBadHoleInTheBag.Add(new ConcurrentBagItem());
}

class ConcurrentBagItem { }

2. Execute with or without debugger

Actual result:

An unhandled exception of type 'System.AccessViolationException' occurred in System.Collections.Concurrent.dll
Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

Expected result:

Works without error, as in .Net 9.

Please introduce ConcurrentBag - from .Net 8 because uinstable work in .Net 9 breaks my app

[drweb86]

If to go through stack trace - System.Linq is third one, Ion double click on it VIsual Studio 2022 crashes (!).

[ViktorHofer]

@dotnet/area-system-collections

[stephentoub]

It's very unlikely this is actually related to ConcurrentBag. It's more likely some code in your app is resulting in corruption that then appears as an AV in other code, in this case in CB. Without a repro or crash dump, though, we can't investigate.

[drweb86]

Ill try to create repro then ср, 4 дек. 2024 г., 13:49 Stephen Toub ***@***.***>:

…

It's very unlikely this is actually related to ConcurrentBag. It's more likely some code in your app is resulting in corruption that then appears as an AV in other code, in this case in CB. Without a repro or crash dump, though, we can't investigate. — Reply to this email directly, view it on GitHub <#110355 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABD6N3JMYBH22IJUFRXLKJ32D3M4PAVCNFSM6AAAAABS5ZL6IKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKMJWHE2DCMZZGA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[drweb86]

Here's the reproduction sample

using System.Collections.Concurrent;

var breakingBadHoleInTheBag = new ConcurrentBag<ConcurrentBagItem>();

int tries = 500000;
while (tries-- > 0)
{
    breakingBadHoleInTheBag.SingleOrDefault(x => x == (object)breakingBadHoleInTheBag);
    breakingBadHoleInTheBag.Add(new ConcurrentBagItem());
}

class ConcurrentBagItem { }

Build for .Net 9 and run => Access Violation,
Build for .Net 8 and run => No error.

Please return .Net 8 implementation since other software might expect old behavior, or new one create with postsfix ConcurrentBagV2/put into breaking changes list.

I updated first post with steps.

[stephentoub]

Thanks for the repro.

This is not about the ConcurrentBag implementation.

I suspect this may be the same as the issue fixed by #109074. If you add <CETCompat>false</CETCompat> into a PropertyGroup in your csproj, does the problem go away?

[drweb86]

@stephentoub ,

Adding

<CETCompat>false</CETCompat>

worked.

But guys, seriously, we're in the dark times, when its needed to modify csproj config to make ConcurrentBag work.

[stephentoub]

But guys, seriously, we're in the dark times, when its needed to modify csproj config to make ConcurrentBag work.

Again, this has little to do with ConcurrentBag. It is a runtime bug to do with Intel's CET security mechanism, it's already been fixed in main with #109074 and it's being fixed in 9.0 with #109548 (cc: @janvorli, @jeffschwMSFT). I mentioned the csproj property to both confirm this is the same problem and to give you a temporary workaround.

[stephentoub]

Closing as a duplicate of #109074. Thanks for reporting.

[drweb86]

@stephentoub Thanks!