Suppress GS cookie checks in method epilogs (#40637)

The information about end of GS cookie scope recorded in GC info is not accurate and it cannot even be made accurate without redesign that is not worth it. Detect end of GS cookie scope by comparing it with current SP instead.

Fixes #13041

diff --git a/src/coreclr/src/vm/eetwain.cpp b/src/coreclr/src/vm/eetwain.cpp
index 41008aac175fa4c2a49e4de8ffeb6cfe964f78c2..88ba0a6b6f7f3ac07e0cff36c6d8b9a3506d687a 100644 (file)
--- a/src/coreclr/src/vm/eetwain.cpp
+++ b/src/coreclr/src/vm/eetwain.cpp
@@ -5626,11 +5626,14 @@ void * EECodeManager::GetGSCookieAddr(PREGDISPLAY     pContext,
     INT32 spOffsetGSCookie = gcInfoDecoder.GetGSCookieStackSlot();
     if (spOffsetGSCookie != NO_GS_COOKIE)
     {
-        if(relOffset >= gcInfoDecoder.GetGSCookieValidRangeStart()
-            && relOffset < gcInfoDecoder.GetGSCookieValidRangeEnd())
+        if(relOffset >= gcInfoDecoder.GetGSCookieValidRangeStart())
         {
-            SIZE_T baseStackSlot = GetCallerSp(pContext);
-            return (LPVOID)( spOffsetGSCookie + baseStackSlot );
+            TADDR ptr = GetCallerSp(pContext) + spOffsetGSCookie;
+
+            // Detect the end of GS cookie scope by comparing its address with SP
+            // gcInfoDecoder.GetGSCookieValidRangeEnd() is not accurate. It does not
+            // account for GS cookie going out of scope inside epilog or multiple epilogs.
+            return (LPVOID) ((ptr >= pContext->SP) ? ptr : NULL);
         }
     }
     return NULL;