Assembly.Location returns `/` instead of the actual path intermittently

[jkotas]

Large internal Microsoft workload observed Assembly.Location sometimes returning / instead of the actual path after upgrading to recent .NET 8 build on Linux.

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Issue Details

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Large internal Microsoft workload observed Assembly.Location sometimes returning / instead of the actual path after upgrading to recent .NET 8 build on Linux.

Author:	jkotas
Assignees:	-
Labels:	area-AssemblyLoader-coreclr, untriaged, needs-area-label
Milestone:	-

[jkotas]

I suspect that this is a race condition caused by SString internally changing its encoding.

One thread can be changing the encoding from UTF8 to UTF16 while the other thread is operating on the string. The other thread may see encoding set to UTF8, but the actual payload can be converted to UTF16 already. It would explain how the method can return / instead of the actual path /abc/def/assembly.dll.

@AaronRobinsonMSFT @jkoritzinsky You are familiar with how SString works. Would you mind reviewing all places that access PEImage::m_path and check whether there may be a race condition like what I have described? (I have taken a cursory look, but I have not found anything obvious.)

[mangod9]

the race wouldnt be Linux specific would it?

[jkotas]

the race wouldnt be Linux specific would it?

Depends. We have many Windows vs. non-Windows ifdefs in the vm. The race condition can be triggered by a code under non-Windows ifdef.

[AaronRobinsonMSFT]

the race wouldnt be Linux specific would it?

Depends. We have many Windows vs. non-Windows ifdefs in the vm. The race condition can be triggered by a code under non-Windows ifdef.

It is also possible, quite likely actually, this is on all platforms and the Linux workload in question was simply the first to find it.