SIGBUS on macOS 15.1

[jonpryor]

Description

After upgrading to macOS 15.1 (and .NET 8.0.403?), dotnet/java-interop unit tests started crashing while trying to create a Java VM from managed code.

Reproduction Steps

1. Use macOS x64

2. Install Microsoft OpenJDK 17

3. Extract net8.0.8-sigbus.zip

4. Build and run the project:

    dotnet run /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib
   

5. Check the shell exit status:

    echo $?
   

Expected behavior

All messages printed:

start!
loaded lib /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib; c=107c85f00
calling JNI_CreateJavaVM
JNI_CreateJavaVM returned 0

In particular, JNI_CreateJavaVM returned.

$? should be 0.

Actual behavior

Not all messages are printed:

start!
loaded lib /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib; c=108366f00
calling JNI_CreateJavaVM

echo $? prints 138, which means it exited via SIGBUS.

Regression?

This wasn't happening to me last week! (Note: within the last week I installed .NET 8.0.403, up from 8.0.204, and installed macOS 15.1, up from 15.0.)

Known Workarounds

No response

Configuration

• Which version of .NET is the code running on? 8.0.403
• What OS and version, and what distro if applicable? macOS 15.1
• What is the architecture (x64, x86, ARM, ARM64)? x64 (not arm64, not Rosetta. Real x64!)
• Do you know whether it is specific to that configuration?: No idea

Other information

Using self-contained builds shows that the issue was introduced between 8.0.7 and 8.0.8.

It works with 8.0.7:

% dotnet publish --sc -p:RuntimeFrameworkVersion=8.0.7
% ./bin/Release/net8.0/osx-x64/net8.0.8-sigbus /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib
start!
loaded lib /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib; c=106b15f00
calling JNI_CreateJavaVM
JNI_CreateJavaVM returned 0

It fails with 8.0.8:

% dotnet publish --sc -p:RuntimeFrameworkVersion=8.0.8
% ./bin/Release/net8.0/osx-x64/net8.0.8-sigbus /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib
start!
loaded lib /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib; c=10cd6df00
calling JNI_CreateJavaVM
zsh: bus error  ./bin/Release/net8.0/osx-x64/net8.0.8-sigbus 

Even better, the self-contained build shows "bus error" in the output!

See also a Discord discussion (which only spans ~3 hours…), which shows that the crash is from:

• https://github.com/dotnet/runtime/blob/v8.0.4/src/coreclr/pal/src/exception/machexception.cpp#L901

Running within lldb shows:

(lldb) p * (CONTEXT*)(ts64.__rsp-sizeof(CONTEXT) - ((ts64.__rsp-sizeof(CONTEXT))%16) - sizeof(EXCEPTION_RECORD))
…lots of output…

(lldb) p * (CONTEXT*)(ts64.__rsp-sizeof(CONTEXT) - ((ts64.__rsp-sizeof(CONTEXT))%16) - sizeof(EXCEPTION_RECORD) - sizeof(MachExceptionInfo))
error: Couldn't apply expression side effects : Couldn't dematerialize a result variable: couldn't read its memory

i.e. the subtraction of sizeof(MachExceptionInfo) from FramePointer results in an invalid address: https://github.com/dotnet/runtime/blob/v8.0.4/src/coreclr/pal/src/exception/machexception.cpp#L899C5-L899C17

[jonpryor]

@akoeplinger @janvorli @jkotas

[jonpryor]

"Workaround" (for me): Separately install the .NET 8.0.206 binaries. I extracted the binaries into $HOME/Downloads/dotnet-sdk-8.0.206-osx-x64.

Using the 8.0.206 install works:

% ~/Downloads/dotnet-sdk-8.0.206-osx-x64/dotnet run /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib
start!
loaded lib /Library/Java/JavaVirtualMachines/microsoft-17.jdk/Contents/Home/lib/libjli.dylib; c=10c261f00
calling JNI_CreateJavaVM
JNI_CreateJavaVM returned 0

% echo $?
0

Explicitly using 8.0.206 also allows my dotnet/java-interop unit tests to run (yay!). (I haven't tried any other versions.)

What didn't work for me:

• Adding global.json and setting sdk:version to 8.0.204 did not work:

  { "sdk": { "version": "8.0.204" } }

• "Removing" (by renaming) /usr/local/share/dotnet/sdk/8.0.403

[akoeplinger]

we also tried 8.0.10 (which includes #107199) and it still crashes there

Note that this is on real x64 macOS, not Rosetta

[jonpryor]

Note that "tried 8.0.10" was via dotnet publish --sc -p:RuntimeFrameworkVersion=8.0.10.

[jkotas]

Likely related to #104818 cc @mikelle-rogers

[janvorli]

@jonpryor are you running it on real macOS x64 or on arm64 with rosetta?
Edited: Ah, I've missed that you've already mentioned that it was not rosetta.

[janvorli]

I don't have access to that discord discussion (I have a private discord account), but let me try to repro that on my local x64 mac.

[MichalPetryka]

I don't have access to that discord discussion (I have a private discord account), but let me try to repro that on my local x64 mac.

It's on the public DotNetEvolution Discord that's linked in the repo readme.

[janvorli]

Hmm, my mac mini is too old, it cannot install 15.1. @jonpryor could you please get me a disassembly at the place where the fault occurs? Just disass -s $pc in lldb at the crash site. And then register read output so that I can see what the instruction was doing. If you can keep the lldb open until I ask for more info, it would be great.