Fix CET - remove writing to shadow stack#103171
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mangod9 merged 1 commit intodotnet:mainfrom Jun 8, 2024
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The reason why I have not detected that when testing my previous change locally was that I was testing it on machine with non-english Windows. I haven't realized the coreclr test results parsing scripts crash when parsing output on windows that are not running with english locale and so only the results of the tests that were not combined into the large test units are shown. And none of those tests was hitting the problem. |
mangod9
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Jun 7, 2024
In my recent fix for failures with CET enabled, I have also added a call to the _wrssq intrinsic to push an address to shadow stack. It turns out that instruction is privileged and cannot be used by user code. Moreover, I have realized that it is not needed at all there, so I am removing it.
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I was wondering if the instruction must be privileged, but figured “if tests pass, it might be not” :) |
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The docs are somewhat arcane on what instructions are allowed and when. |
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In my recent fix for failures with CET enabled, I have also added a call to the
_wrssqintrinsic to push an address to shadow stack. It turns out that instruction is privileged and cannot be used by user code. Moreover, I have realized that it is not needed at all there, so I am removing it.