gnu: flex: Fix CVE-2016-6354.

* gnu/packages/flex.scm (flex)[source]: Add patch.
* gnu/packages/patches/flex-CVE-2016-6354.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu/local.mk

@@ -504,6 +504,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/findutils-localstatedir.patch		\
   %D%/packages/patches/findutils-test-xargs.patch		\
   %D%/packages/patches/flashrom-use-libftdi1.patch		\
+  %D%/packages/patches/flex-CVE-2016-6354.patch			\
   %D%/packages/patches/flint-ldconfig.patch			\
   %D%/packages/patches/fltk-shared-lib-defines.patch		\
   %D%/packages/patches/fltk-xfont-on-demand.patch		\

gnu/packages/flex.scm

@@ -36,6 +36,7 @@
              (method url-fetch)
              (uri (string-append "mirror://sourceforge/flex/flex-"
                                  version ".tar.bz2"))
+             (patches (search-patches "flex-CVE-2016-6354.patch"))
              (sha256
               (base32
                "1sdqx63yadindzafrq1w31ajblf9gl1c301g068s20s7bbpi3ri4"))))

gnu/packages/patches/flex-CVE-2016-6354.patch

@@ -0,0 +1,30 @@
+Fix CVE-2016-6354 (Buffer overflow in generated code (yy_get_next_buffer).
+
+https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-6354
+https://security-tracker.debian.org/tracker/CVE-2016-6354
+
+Patch copied from upstream source repository:
+https://github.com/westes/flex/commit/a5cbe929ac3255d371e698f62dc256afe7006466
+
+From a5cbe929ac3255d371e698f62dc256afe7006466 Mon Sep 17 00:00:00 2001
+From: Will Estes <westes575@gmail.com>
+Date: Sat, 27 Feb 2016 11:56:05 -0500
+Subject: [PATCH] Fixed incorrect integer type
+
+---
+ src/flex.skl | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/flex.skl b/src/flex.skl
+index 36a526a..64f853d 100644
+--- a/src/flex.skl
++++ b/src/flex.skl
+@@ -1703,7 +1703,7 @@ int yyFlexLexer::yy_get_next_buffer()
+ 
+ 	else
+ 		{
+-			yy_size_t num_to_read =
++			int num_to_read =
+ 			YY_CURRENT_BUFFER_LVALUE->yy_buf_size - number_to_move - 1;
+ 
+ 		while ( num_to_read <= 0 )