emacs-27 2c5f215: Avoid crashes in Mew due to corrupted tool-bar label

[Eli Zaretskii]

branch: emacs-27
commit 2c5f21541957e2420e54ab2a70883140811708f7
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Avoid crashes in Mew due to corrupted tool-bar label
    
    * src/gtkutil.c (update_frame_tool_bar): Don't keep around a
    'char *' pointer to a Lisp string's contents when calling Lisp,
    because that could relocate string data; keep the Lisp string
    itself instead.  This avoids crashes in Mew.  (Bug#46791)
---
 src/gtkutil.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/gtkutil.c b/src/gtkutil.c
index d824601..825fbe1 100644
--- a/src/gtkutil.c
+++ b/src/gtkutil.c
@@ -5019,11 +5019,10 @@ update_frame_tool_bar (struct frame *f)
       GtkWidget *wbutton = NULL;
       Lisp_Object specified_file;
       bool vert_only = ! NILP (PROP (TOOL_BAR_ITEM_VERT_ONLY));
-      const char *label
-       = (EQ (style, Qimage) || (vert_only && horiz)) ? NULL
-       : STRINGP (PROP (TOOL_BAR_ITEM_LABEL))
-       ? SSDATA (PROP (TOOL_BAR_ITEM_LABEL))
-       : "";
+      Lisp_Object label
+       = (EQ (style, Qimage) || (vert_only && horiz))
+       ? Qnil
+       : PROP (TOOL_BAR_ITEM_LABEL);
 
       ti = gtk_toolbar_get_nth_item (GTK_TOOLBAR (wtoolbar), j);
 
@@ -5136,8 +5135,11 @@ update_frame_tool_bar (struct frame *f)
 
       /* If there is an existing widget, check if it's stale; if so,
         remove it and make a new tool item from scratch.  */
-      if (ti && xg_tool_item_stale_p (wbutton, stock_name, icon_name,
-                                     img, label, horiz))
+      if (ti && xg_tool_item_stale_p (wbutton, stock_name, icon_name, img,
+                                     NILP (label)
+                                     ? NULL
+                                     : STRINGP (label) ? SSDATA (label) : "",
+                                     horiz))
        {
          gtk_container_remove (GTK_CONTAINER (wtoolbar),
                                GTK_WIDGET (ti));
@@ -5194,7 +5196,11 @@ update_frame_tool_bar (struct frame *f)
 #else
          if (w) gtk_misc_set_padding (GTK_MISC (w), hmargin, vmargin);
 #endif
-          ti = xg_make_tool_item (f, w, &wbutton, label, i, horiz, text_image);
+          ti = xg_make_tool_item (f, w, &wbutton,
+                                 NILP (label)
+                                 ? NULL
+                                 : STRINGP (label) ? SSDATA (label) : "",
+                                 i, horiz, text_image);
           gtk_toolbar_insert (GTK_TOOLBAR (wtoolbar), ti, j);
         }