Fix memory leak in fontset handling

* src/font.c (copy_font_spec): Make a deep copy of the input
argument FONT.  (Bug#21651)

1 files changed, 4 insertions, 1 deletions

diff --git a/src/font.c b/src/font.c
index a52a653d29b..be55ce9bc7b 100644
--- a/src/font.c
+++ b/src/font.c
@@ -3981,7 +3981,10 @@ copy_font_spec (Lisp_Object font)
   pcdr = spec->props + FONT_EXTRA_INDEX;
   for (tail = AREF (font, FONT_EXTRA_INDEX); CONSP (tail); tail = XCDR (tail))
     if (!EQ (XCAR (XCAR (tail)), QCfont_entity))
-      *pcdr = Fcons (XCAR (tail), Qnil), pcdr = xcdr_addr (*pcdr);
+      {
+        *pcdr = Fcons (Fcons (XCAR (XCAR (tail)), CDR (XCAR (tail))), Qnil);
+        pcdr = xcdr_addr (*pcdr);
+      }
 
   XSETFONT (new_spec, spec);
   return new_spec;