From: Eli Zaretskii <eliz@gnu.org>
Date: Sun, 5 Dec 2021 15:34:05 +0000 (+0200)
Subject: Fix out-of-bounds access in xdisp.c
X-Git-Tag: emacs-29.0.90~3612^2~3^2~15
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=509dec902c45bc11cd8ff6664795b471d451742c;p=emacs.git

Fix out-of-bounds access in xdisp.c

* src/xdisp.c (produce_stretch_glyph): Avoid indexing it->stack
with a negative index.  Reported by Po Lu <luangruo@yahoo.com>.
---

diff --git a/src/xdisp.c b/src/xdisp.c
index b2eeb1105b1..45b502590d1 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -30391,7 +30391,8 @@ produce_stretch_glyph (struct it *it)
   if (width > 0 && height > 0 && it->glyph_row)
     {
       Lisp_Object o_object = it->object;
-      Lisp_Object object = it->stack[it->sp - 1].string;
+      Lisp_Object object =
+	it->sp > 0 ? it->stack[it->sp - 1].string : it->string;
       int n = width;
 
       if (!STRINGP (object))