From: Eli Zaretskii <eliz@gnu.org>
Date: Sun, 19 Sep 2021 18:39:18 +0000 (+0300)
Subject: Avoid segfaults due to 'bug-reference-mode'
X-Git-Tag: emacs-28.0.90~825
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=558ca61cbdba5315c058f70d1ba2232f1391739e;p=emacs.git

Avoid segfaults due to 'bug-reference-mode'

* src/xdisp.c (handle_fontified_prop): Set the frame's
inhibit_clear_image_cache flag around calls to
'fontification-functions', to avoid Lisp triggering the clearing
of image and/or face caches behind redisplay's back.  (Big#50571)
---

diff --git a/src/xdisp.c b/src/xdisp.c
index 2e72f6b5915..b777d1b2825 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -4288,12 +4288,17 @@ handle_fontified_prop (struct it *it)
       struct buffer *obuf = current_buffer;
       ptrdiff_t begv = BEGV, zv = ZV;
       bool old_clip_changed = current_buffer->clip_changed;
+      bool saved_inhibit_flag = it->f->inhibit_clear_image_cache;
 
       val = Vfontification_functions;
       specbind (Qfontification_functions, Qnil);
 
       eassert (it->end_charpos == ZV);
 
+      /* Don't allow Lisp that runs from 'fontification-functions'
+	 clear our face and image caches behind our back.  */
+      it->f->inhibit_clear_image_cache = true;
+
       if (!CONSP (val) || EQ (XCAR (val), Qlambda))
 	safe_call1 (val, pos);
       else
@@ -4327,6 +4332,7 @@ handle_fontified_prop (struct it *it)
 	    }
 	}
 
+      it->f->inhibit_clear_image_cache = saved_inhibit_flag;
       unbind_to (count, Qnil);
 
       /* Fontification functions routinely call `save-restriction'.