From d72b877e45987b8869ceb6f86e126819b1bb3f41 Mon Sep 17 00:00:00 2001
From: Michael Matz <matz@suse.de>
Date: Fri, 15 Mar 2019 13:17:58 +0100
Subject: [PATCH] Fix invalid memory access in preprocess_end

when an error is thrown macro_stack might point to
unwound local variables, we can't access them.
---
 tccpp.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tccpp.c b/tccpp.c
index 4e60720..d309f13 100644
--- a/tccpp.c
+++ b/tccpp.c
@@ -3625,8 +3625,13 @@ ST_FUNC void preprocess_start(TCCState *s1, int is_asm)
 /* cleanup from error/setjmp */
 ST_FUNC void preprocess_end(TCCState *s1)
 {
-    while (macro_stack)
-        end_macro();
+    /* Normally macro_stack is NULL here, except if an
+       error was thrown; then it can point to allocated storage
+       or to some stack variables, but those are unwound via
+       setjmp already, so can't be accessed.  Only two choices:
+       either we leak memory or we access invalid memory.  The
+       former is the better choice.  */
+    macro_stack = NULL;
     macro_ptr = NULL;
 }