From f5073685562dc7045d0f2a89722d4d948a3500b9 Mon Sep 17 00:00:00 2001
From: sebres <sebres@users.sourceforge.net>
Date: Tue, 2 Jun 2020 17:01:52 +0000
Subject: avoid segfault if Tcl_FreeParse, if parse structure remains
 uninitialized (parse.tokenPtr may be used uninitialized, for instance it
 returns from Tcl_ParseCommand etc with error before TclParseInit gets called)

---
 generic/tclParse.c | 35 ++++++++++++++++-------------------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/generic/tclParse.c b/generic/tclParse.c
index b1b8037..48d86ef 100644
--- a/generic/tclParse.c
+++ b/generic/tclParse.c
@@ -268,16 +268,16 @@ Tcl_ParseCommand(
 				 * point to char after terminating one. */
     int scanned;
 
+    if (numBytes < 0 && start) {
+	numBytes = strlen(start);
+    }
+    TclParseInit(interp, start, numBytes, parsePtr);
     if ((start == NULL) && (numBytes != 0)) {
 	if (interp != NULL) {
 	    Tcl_SetResult(interp, "can't parse a NULL pointer", TCL_STATIC);
 	}
 	return TCL_ERROR;
     }
-    if (numBytes < 0) {
-	numBytes = strlen(start);
-    }
-    TclParseInit(interp, start, numBytes, parsePtr);
     parsePtr->commentStart = NULL;
     parsePtr->commentSize = 0;
     parsePtr->commandStart = NULL;
@@ -1421,16 +1421,15 @@ Tcl_ParseVarName(
     int varIndex;
     unsigned array;
 
-    if ((numBytes == 0) || (start == NULL)) {
-	return TCL_ERROR;
-    }
-    if (numBytes < 0) {
+    if (numBytes < 0 && start) {
 	numBytes = strlen(start);
     }
-
     if (!append) {
 	TclParseInit(interp, start, numBytes, parsePtr);
     }
+    if ((numBytes == 0) || (start == NULL)) {
+	return TCL_ERROR;
+    }
 
     /*
      * Generate one token for the variable, an additional token for the name,
@@ -1707,16 +1706,15 @@ Tcl_ParseBraces(
     register const char *src;
     int startIndex, level, length;
 
-    if ((numBytes == 0) || (start == NULL)) {
-	return TCL_ERROR;
-    }
-    if (numBytes < 0) {
+    if (numBytes < 0 && start) {
 	numBytes = strlen(start);
     }
-
     if (!append) {
 	TclParseInit(interp, start, numBytes, parsePtr);
     }
+    if ((numBytes == 0) || (start == NULL)) {
+	return TCL_ERROR;
+    }
 
     src = start;
     startIndex = parsePtr->numTokens;
@@ -1904,16 +1902,15 @@ Tcl_ParseQuotedString(
 				 * the quoted string's terminating close-quote
 				 * if the parse succeeds. */
 {
-    if ((numBytes == 0) || (start == NULL)) {
-	return TCL_ERROR;
-    }
-    if (numBytes < 0) {
+    if (numBytes < 0 && start) {
 	numBytes = strlen(start);
     }
-
     if (!append) {
 	TclParseInit(interp, start, numBytes, parsePtr);
     }
+    if ((numBytes == 0) || (start == NULL)) {
+	return TCL_ERROR;
+    }
 
     if (TCL_OK != ParseTokens(start+1, numBytes-1, TYPE_QUOTE, TCL_SUBST_ALL,
 	    parsePtr)) {
-- 
cgit v0.12