[Mono] Fix OP_CHECK_THIS to read 1 byte instead of 4/8 on x86/x64/LLVM. #74638
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lateralusX
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area-Codegen-meta-mono
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lateralusX
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lambdageek
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Aug 26, 2022
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We should backport this |
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/azp run runtime-extra-platforms |
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Azure Pipelines successfully started running 1 pipeline(s). |
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Failures in runtime-extra-platforms seems unrelated and appears on multiple other PR's. |
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/backport to release/7.0 |
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Started backporting to release/7.0: https://github.com/dotnet/runtime/actions/runs/2950110740 |
Current implementation of OP_CHECK_THIS on x86/x64 and LLVM does a memory read of at least 4 bytes. This creates an issue when the target is a managed pointer, since that could point to the interior of a type, meaning it can read pass the allocated memory causing a crash. Fix change the size of the read to one byte since the only reason doing the read is to validate that the reference, managed pointer is not NULL. Reading only one byte is also inline with how it is implemented on arm/arm64, and it will reduce potential unaligned reads on x86/x64. Full fix for, dotnet#74179.
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Rebased to get CI run after #74567 had been merged and tests had been re-enabled. |
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/azp run runtime-extra-platforms |
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Azure Pipelines successfully started running 1 pipeline(s). |
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Failures looks unrelated and had failed in similar ways on other PR's as well. |
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Current implementation of OP_CHECK_THIS on x86/x64 and LLVM does a memory read of at least 4 bytes. This creates an issue when the target is a managed pointer, since that could point to the interior of a type, meaning it can read pass the allocated memory causing a crash. Fix change the size of the read to one byte since the only reason doing the read is to validate that the reference, managed pointer is not NULL. Reading only one byte is also inline with how it is implemented on arm/arm64, and it will reduce potential unaligned reads on x86/x64.
Full fix for, #74179.
Fixes #74179