Fix x86 EH for UnmanagedCallersOnly methods#58796
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janvorli merged 2 commits intodotnet:mainfrom Sep 9, 2021
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There is a bug in the exception handling on x86 when exception is propagated from a method marked with UnmanagedCallersOnly attribute to an immediate caller that's also managed (and calls the method via a native delegate). In this case, there is no native frame in between and the stack walker accidentally skips the InlinedCallFrame processing during first pass of exception handling. The InlinedCallFrame is expected to be processed before the related PInvoke IL stub and it doesn't happen in this case, as a native frame is required to make the stack frame iterator move to the explicit InlinedCallFrame. The fact that it is not processed results in ignoring the upper limit on the stack walk and walking the stack further than expected. This change fixes it by detecting the direct transition from UnmanagedCallersOnly to managed caller and forces the stack frame iterator to process the InlinedCallFrame.
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| #ifdef TARGET_X86 | ||
| hdrInfo gcHdrInfo; | ||
| DecodeGCHdrInfo(m_crawl.codeInfo.GetGCInfoToken(), 0, &gcHdrInfo); |
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All other places that decode GCInfo in this file go through m_crawl.GetCodeManager(). Is it worth following the pattern?
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Good idea, but let me do that as a separate cleanup so that this change is just a fix for the bug. I will need to add a new method to the EECodeManager and then I'd use it in the exceptionhandling.cpp too where we currently also have this raw decoding.
AaronRobinsonMSFT
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There is a bug in the exception handling on x86 when exception is
propagated from a method marked with UnmanagedCallersOnly attribute to
an immediate caller that's also managed (and calls the method via a
native delegate). In this case, there is no native frame in between and
the stack walker accidentally skips the InlinedCallFrame processing
during first pass of exception handling. The InlinedCallFrame is expected
to be processed before the related PInvoke IL stub and it doesn't happen
in this case, as a native frame is required to make the stack frame iterator
move to the explicit InlinedCallFrame. The fact that it is not processed
results in ignoring the upper limit on the stack walk and walking the stack
further than expected.
This change fixes it by detecting the direct transition from
UnmanagedCallersOnly to managed caller and forces the stack frame
iterator to process the InlinedCallFrame.
Fixes #57915