Copied from Debian.

From: Carlos Garcia Campos <cgarcia@igalia.com>
Date: Mon, 19 Nov 2018 12:33:07 +0100
Subject: ft: Use FT_Done_MM_Var instead of free when available in
 cairo_ft_apply_variations

Fixes a crash when using freetype >= 2.9

[This is considered to be security-sensitive because WebKitGTK+ sets its
own memory allocator, which is not compatible with system free(), making
this a remotely triggerable denial of service or memory corruption.]

Origin: upstream, commit:90e85c2493fdfa3551f202ff10282463f1e36645
Bug: https://gitlab.freedesktop.org/cairo/cairo/merge_requests/5
Bug-Debian: https://bugs.debian.org/916389
Bug-CVE: CVE-2018-19876
---
 src/cairo-ft-font.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/cairo-ft-font.c b/src/cairo-ft-font.c
index 325dd61..981973f 100644
--- a/src/cairo-ft-font.c
+++ b/src/cairo-ft-font.c
@@ -2393,7 +2393,11 @@ skip:
 done:
         free (coords);
         free (current_coords);
+#if HAVE_FT_DONE_MM_VAR
+        FT_Done_MM_Var (face->glyph->library, ft_mm_var);
+#else
         free (ft_mm_var);
+#endif
     }
 }