Re: [PATCH v4 0/2] MR7064: ntdll: Check for invalid %gs value in 32-bit code on WoW64.

[Jinoh Kang (＠iamahuman)]

Jinoh Kang (@iamahuman) commented about dlls/ntdll/unix/signal_x86_64.c:
>          /* send EXCEPTION_EXECUTE_FAULT only if data execution prevention is enabled */
>          if (!(flags & MEM_EXECUTE_OPTION_DISABLE)) rec.ExceptionInformation[0] = EXCEPTION_READ_FAULT;
>      }
> -
>    if (is_wow64() && (CS_sig(ucontext) == cs64_sel) && check_invalid_gs( ucontext, &context.c ))

Pardon my mistake earlier. GS restoration is actually unncessary in system code. The condition should be `CS_sig(ucontext) == cs64_sel && virtual_is_valid_code_address( instr, 1 )`.

Also, since you're probably on macOS, have you tried !6866?