From 9220b96d3c8ec555212d8aee0f81f1c898c75190 Mon Sep 17 00:00:00 2001
From: "jan.nijtmans" <nijtmans@users.sourceforge.net>
Date: Sun, 1 Oct 2023 19:06:33 +0000
Subject: [PATCH] Fix [7371b6270b]: AddressSanitizer use-after-return detection
 breaks NRE tests, coroutines. (patch by chrstphrchvz, with some minor
 modifications)

---
 generic/tclBasic.c    | 39 +++++++++++++++++++++++++++++++++++++--
 generic/tclInt.decls  |  6 +++++-
 generic/tclIntDecls.h |  8 +++++---
 generic/tclStubInit.c |  2 +-
 generic/tclTest.c     | 14 +++++++-------
 5 files changed, 55 insertions(+), 14 deletions(-)

diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 26530c3924a3..096ce20e513a 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -23,7 +23,42 @@
 #include "tommath.h"
 #include <math.h>
 #include <assert.h>
+
+/*
+ * Bug 7371b6270b: to check C call stack depth, prefer an approach which is
+ * compatible with AddressSanitizer (ASan) use-after-return detection.
+ */
+
+#if defined(HAVE_INTRIN_H)
+#include <intrin.h> /* for _AddressOfReturnAddress() */
+#endif
+
+/*
+ * As suggested by
+ * https://clang.llvm.org/docs/LanguageExtensions.html#has-builtin
+ */
+#ifndef __has_builtin
+#define __has_builtin(x) 0 /* for non-clang compilers */
+#endif
 
+void *
+TclGetCStackPtr(void)
+{
+#if defined(HAVE_INTRIN_H)
+  return _AddressOfReturnAddress();
+#elif __GNUC__ || __has_builtin(__builtin_frame_address)
+  return __builtin_frame_address(0);
+#else
+  int unused = 0;
+  /*
+   * LLVM recommends using volatile:
+   * https://github.com/llvm/llvm-project/blob/llvmorg-10.0.0-rc1/clang/lib/Basic/Stack.cpp#L31
+   */
+  int *volatile stackLevel = &unused;
+  return (void *)stackLevel;
+#endif
+}
+
 #define INTERP_STACK_INITIAL_SIZE 2000
 #define CORO_STACK_INITIAL_SIZE    200
 
@@ -8824,8 +8859,8 @@ TclNRCoroutineActivateCallback(
 {
     CoroutineData *corPtr = (CoroutineData *)data[0];
     int type = PTR2INT(data[1]);
-    int numLevels, unused;
-    int *stackLevel = &unused;
+    int numLevels;
+    void *stackLevel = TclGetCStackPtr();
 
     if (!corPtr->stackLevel) {
         /*
diff --git a/generic/tclInt.decls b/generic/tclInt.decls
index ca122f768748..993cc5d613b4 100644
--- a/generic/tclInt.decls
+++ b/generic/tclInt.decls
@@ -540,6 +540,11 @@ declare 218 {
 }
 
 # for use in tclTest.c
+
+# Bug 7371b6270b
+declare 223 {
+    void *TclGetCStackPtr(void)
+}
 declare 224 {
     TclPlatformType *TclGetPlatform(void)
 }
@@ -586,7 +591,6 @@ declare 235 {
     void TclInitVarHashTable(TclVarHashTable *tablePtr, Namespace *nsPtr)
 }
 
-
 # TIP 337 made this one public
 declare 236 {
     void TclBackgroundException(Tcl_Interp *interp, int code)
diff --git a/generic/tclIntDecls.h b/generic/tclIntDecls.h
index e9587332c856..cb1332753f8d 100644
--- a/generic/tclIntDecls.h
+++ b/generic/tclIntDecls.h
@@ -532,7 +532,8 @@ EXTERN void		TclPopStackFrame(Tcl_Interp *interp);
 /* Slot 220 is reserved */
 /* Slot 221 is reserved */
 /* Slot 222 is reserved */
-/* Slot 223 is reserved */
+/* 223 */
+EXTERN void *		TclGetCStackPtr(void);
 /* 224 */
 EXTERN TclPlatformType * TclGetPlatform(void);
 /* 225 */
@@ -875,7 +876,7 @@ typedef struct TclIntStubs {
     void (*reserved220)(void);
     void (*reserved221)(void);
     void (*reserved222)(void);
-    void (*reserved223)(void);
+    void * (*tclGetCStackPtr) (void); /* 223 */
     TclPlatformType * (*tclGetPlatform) (void); /* 224 */
     Tcl_Obj * (*tclTraceDictPath) (Tcl_Interp *interp, Tcl_Obj *rootPtr, int keyc, Tcl_Obj *const keyv[], int flags); /* 225 */
     int (*tclObjBeingDeleted) (Tcl_Obj *objPtr); /* 226 */
@@ -1289,7 +1290,8 @@ extern const TclIntStubs *tclIntStubsPtr;
 /* Slot 220 is reserved */
 /* Slot 221 is reserved */
 /* Slot 222 is reserved */
-/* Slot 223 is reserved */
+#define TclGetCStackPtr \
+	(tclIntStubsPtr->tclGetCStackPtr) /* 223 */
 #define TclGetPlatform \
 	(tclIntStubsPtr->tclGetPlatform) /* 224 */
 #define TclTraceDictPath \
diff --git a/generic/tclStubInit.c b/generic/tclStubInit.c
index 9dc3ca0605aa..34bf824ff557 100644
--- a/generic/tclStubInit.c
+++ b/generic/tclStubInit.c
@@ -720,7 +720,7 @@ static const TclIntStubs tclIntStubs = {
     0, /* 220 */
     0, /* 221 */
     0, /* 222 */
-    0, /* 223 */
+    TclGetCStackPtr, /* 223 */
     TclGetPlatform, /* 224 */
     TclTraceDictPath, /* 225 */
     TclObjBeingDeleted, /* 226 */
diff --git a/generic/tclTest.c b/generic/tclTest.c
index 0061da6b78ee..d05ef7df1afe 100644
--- a/generic/tclTest.c
+++ b/generic/tclTest.c
@@ -7390,23 +7390,23 @@ NREUnwind_callback(
     Tcl_Interp *interp,
     int result)
 {
-    int none;
+    void *cStackPtr = TclGetCStackPtr();
     (void)result;
 
     if (data[0] == INT2PTR(-1)) {
-        Tcl_NRAddCallback(interp, NREUnwind_callback, &none, INT2PTR(-1),
+        Tcl_NRAddCallback(interp, NREUnwind_callback, cStackPtr, INT2PTR(-1),
                 INT2PTR(-1), NULL);
     } else if (data[1] == INT2PTR(-1)) {
-        Tcl_NRAddCallback(interp, NREUnwind_callback, data[0], &none,
+        Tcl_NRAddCallback(interp, NREUnwind_callback, data[0], cStackPtr,
                 INT2PTR(-1), NULL);
     } else if (data[2] == INT2PTR(-1)) {
         Tcl_NRAddCallback(interp, NREUnwind_callback, data[0], data[1],
-                &none, NULL);
+                cStackPtr, NULL);
     } else {
         Tcl_Obj *idata[3];
         idata[0] = Tcl_NewIntObj((int) ((char *) data[1] - (char *) data[0]));
         idata[1] = Tcl_NewIntObj((int) ((char *) data[2] - (char *) data[0]));
-        idata[2] = Tcl_NewIntObj((int) ((char *) &none   - (char *) data[0]));
+        idata[2] = Tcl_NewIntObj((int) ((char *) cStackPtr - (char *) data[0]));
         Tcl_SetObjResult(interp, Tcl_NewListObj(3, idata));
     }
     return TCL_OK;
@@ -7452,10 +7452,10 @@ TestNRELevels(
     (void)objv;
 
     if (refDepth == NULL) {
-	refDepth = &depth;
+	refDepth = (ptrdiff_t *)TclGetCStackPtr();
     }
 
-    depth = (refDepth - &depth);
+    depth = (refDepth - (ptrdiff_t *)TclGetCStackPtr());
 
     levels[0] = Tcl_NewIntObj(depth);
     levels[1] = Tcl_NewIntObj(iPtr->numLevels);