gnu: freetype: Fix CVE-2017-{8105,8287}.

* gnu/packages/patches/freetype-CVE-2017-8105.patch,
gnu/packages/patches/freetype-CVE-2017-8287.patch: New files.
* gnu/local.mk (dist_patch_DATA): Add them.
* gnu/packages/fontutils.scm (freetype)[replacement]: New field.
(freetype/fixed): New variable.

gnu/local.mk

@@ -575,6 +575,8 @@ dist_patch_DATA =						\
   %D%/packages/patches/freeimage-CVE-2015-0852.patch		\
   %D%/packages/patches/freeimage-CVE-2016-5684.patch		\
   %D%/packages/patches/freeimage-fix-build-with-gcc-5.patch	\
+  %D%/packages/patches/freetype-CVE-2017-8105.patch		\
+  %D%/packages/patches/freetype-CVE-2017-8287.patch		\
   %D%/packages/patches/fuse-overlapping-headers.patch				\
   %D%/packages/patches/gawk-shell.patch				\
   %D%/packages/patches/gcc-arm-bug-71399.patch			\

gnu/packages/fontutils.scm

@@ -48,6 +48,7 @@
 (define-public freetype
   (package
    (name "freetype")
+   (replacement freetype/fixed)
    (version "2.7.1")
    (source (origin
             (method url-fetch)
@@ -73,6 +74,15 @@ anti-aliased glyph bitmap generation with 256 gray levels.")
    (license license:freetype)           ; some files have other licenses
    (home-page "https://www.freetype.org/")))
 
+(define freetype/fixed
+  (package
+    (inherit freetype)
+    (source
+      (origin
+        (inherit (package-source freetype))
+        (patches (search-patches "freetype-CVE-2017-8105.patch"
+                                 "freetype-CVE-2017-8287.patch"))))))
+
 (define-public ttfautohint
   (package
     (name "ttfautohint")

gnu/packages/patches/freetype-CVE-2017-8105.patch

@@ -0,0 +1,56 @@
+Fix CVE-2017-8105:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-8105
+https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=935
+
+Patch copied from upstream source repository:
+
+https://git.savannah.gnu.org/cgit/freetype/freetype2.git/commit/?id=f958c48ee431bef8d4d466b40c9cb2d4dbcb7791
+
+From f958c48ee431bef8d4d466b40c9cb2d4dbcb7791 Mon Sep 17 00:00:00 2001
+From: Werner Lemberg <wl@gnu.org>
+Date: Fri, 24 Mar 2017 09:15:10 +0100
+Subject: [PATCH] [psaux] Better protect `flex' handling.
+
+Reported as
+
+  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=935
+
+* src/psaux/t1decode.c (t1_decoder_parse_charstrings)
+<callothersubr>: Since there is not a single flex operator but a
+series of subroutine calls, malformed fonts can call arbitrary other
+operators after the start of a flex, possibly adding points.  For
+this reason we have to check the available number of points before
+inserting a point.
+---
+ ChangeLog            | 15 +++++++++++++++
+ src/psaux/t1decode.c |  9 +++++++++
+ 2 files changed, 24 insertions(+)
+
+diff --git a/src/psaux/t1decode.c b/src/psaux/t1decode.c
+index af7b465e..7dd45135 100644
+--- a/src/psaux/t1decode.c
++++ b/src/psaux/t1decode.c
+@@ -780,10 +780,19 @@
+             /* point without adding any point to the outline    */
+             idx = decoder->num_flex_vectors++;
+             if ( idx > 0 && idx < 7 )
++            {
++              /* in malformed fonts it is possible to have other */
++              /* opcodes in the middle of a flex (which don't    */
++              /* increase `num_flex_vectors'); we thus have to   */
++              /* check whether we can add a point                */
++              if ( FT_SET_ERROR( t1_builder_check_points( builder, 1 ) ) )
++                goto Syntax_Error;
++
+               t1_builder_add_point( builder,
+                                     x,
+                                     y,
+                                     (FT_Byte)( idx == 3 || idx == 6 ) );
++            }
+           }
+           break;
+ 
+-- 
+2.12.2
+

gnu/packages/patches/freetype-CVE-2017-8287.patch

@@ -0,0 +1,44 @@
+Fix CVE-2017-8287:
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-8287
+https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=941
+
+Patch copied from upstream source repository:
+https://git.savannah.gnu.org/cgit/freetype/freetype2.git/commit/?id=3774fc08b502c3e685afca098b6e8a195aded6a0
+
+From 3774fc08b502c3e685afca098b6e8a195aded6a0 Mon Sep 17 00:00:00 2001
+From: Werner Lemberg <wl@gnu.org>
+Date: Sun, 26 Mar 2017 08:32:09 +0200
+Subject: [PATCH] * src/psaux/psobjs.c (t1_builder_close_contour): Add safety
+ guard.
+
+Reported as
+
+  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=941
+---
+ ChangeLog          | 8 ++++++++
+ src/psaux/psobjs.c | 8 ++++++++
+ 2 files changed, 16 insertions(+)
+
+diff --git a/src/psaux/psobjs.c b/src/psaux/psobjs.c
+index d18e821a..0baf8368 100644
+--- a/src/psaux/psobjs.c
++++ b/src/psaux/psobjs.c
+@@ -1718,6 +1718,14 @@
+     first = outline->n_contours <= 1
+             ? 0 : outline->contours[outline->n_contours - 2] + 1;
+ 
++    /* in malformed fonts it can happen that a contour was started */
++    /* but no points were added                                    */
++    if ( outline->n_contours && first == outline->n_points )
++    {
++      outline->n_contours--;
++      return;
++    }
++
+     /* We must not include the last point in the path if it */
+     /* is located on the first point.                       */
+     if ( outline->n_points > 1 )
+-- 
+2.12.2
+