Fix VTableCallHolder writeable mapping size with W^X #70093
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The size of this holder is dynamic, but when we are creating the writeable mapping of this holder to initialize its code, we don't take that into account. So in case the holder is located at the end of a memory page and crosses its boundary, the writeable mapping covers only the beginning of the holder and so we either crash during the initialization if the following memory page is not mapped or read only, or we corrupt a completely unrelated memory page in case it is mapped and writeable. The fix is to use the real size of the holder instead of sizeof(...).
jkotas
approved these changes
Jun 1, 2022
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@janvorli Seeing some new (though I think inconsistent) failures in the sdk->installer build for p5 that could be a result of this. May need a backport. |
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@mmitche I have made this fix based on investigations of the installer issue for p6, I was going to port this to p5 as the issue was there too. |
mangod9
approved these changes
Jun 1, 2022
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/backport to release/7.0-preview5 |
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Started backporting to release/7.0-preview5: https://github.com/dotnet/runtime/actions/runs/2423701222 |
ghost
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The size of this holder is dynamic, but when we are creating the writeable
mapping of this holder to initialize its code, we don't take that into account.
So in case the holder is located at the end of a memory page and crosses its
boundary, the writeable mapping covers only the beginning of the holder and
so we either crash during the initialization if the following memory page is
not mapped or read only, or we corrupt a completely unrelated memory page
in case it is mapped and writeable.
The fix is to use the real size of the holder instead of sizeof(...).