[release/11.0] Align CoreCLR GS cookie protection with NativeAOT - #132976
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Fixes #99977 Hosting CoreCLR inside Apple's stock `/usr/bin/lldb` on macOS arm64 fails: `coreclr_initialize` returns `HRESULT 0x8007000C`. `InitGSCookie()` temporarily calls `ClrVirtualProtect(PAGE_READWRITE)` on `s_gsCookie`, which lives in Apple's `__DATA_CONST` segment (via `const`/`READONLY_ATTR`). Apple marks that segment immutable once a Mach exception port owns the process — which happens when CoreCLR is hosted inside LLDB with `PAL_MachExceptionMode` set to avoid Apple's guarded Mach exception-port operations — so the underlying `mprotect` call fails. NativeAOT hit and fixed the identical Apple problem in #99173. Its read-only GS cookie feature is also disabled on WebAssembly, where changing page protections is unnecessary overhead, and on OpenBSD, where `ld.so` marks read-only segments immutable at load time. This PR aligns CoreCLR with that existing NativeAOT platform policy: - Define `FEATURE_READONLY_GS_COOKIE` on all targets except Apple, WebAssembly, and OpenBSD. - `vars.hpp`/`vars.cpp`: `s_gsCookie` keeps its read-only `const`/`READONLY_ATTR` declaration when the feature is enabled; otherwise it is plain writable data. - `ceemain.cpp`: `InitGSCookie()` skips both `ClrVirtualProtect` calls when the feature is disabled. Cookie generation and the write itself are unchanged on every platform. On Apple and OpenBSD, this trades a narrow defense-in-depth mitigation for compatibility with the platform's immutable read-only segments. On WebAssembly, it avoids page-protection overhead that provides no benefit. Other platforms retain the existing read-only cookie behavior. > [!NOTE] > This description was drafted with the assistance of an AI coding agent (GitHub Copilot).
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@jkotas I think this is important to land in 11 to get better SOS mac arm64 support. |
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Tagging subscribers to this area: @agocke |
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It would be better to land the changes to get SOS AOT compiled that avoids this and number of other problems on all platforms. Still, I am ok with backporting. |
jkotas
approved these changes
Aug 31, 2026
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/ba-g Helix monitor doing its thing... |
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Backport of #132925 to release/11.0
/cc @steveisok
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IMPORTANT: If this backport is for a servicing release, please verify that:
release/X.0-staging, notrelease/X.0.release/X.0(no-stagingsuffix).Package authoring no longer needed in .NET 9
IMPORTANT: Starting with .NET 9, you no longer need to edit a NuGet package's csproj to enable building and bump the version.
Keep in mind that we still need package authoring in .NET 8 and older versions.