flex: Backport buffer overflow fix

Fix a heap-based buffer overflow in yy_get_next_buffer()
(CVE-2016-6354).

(From OE-Core rev: 68d56306baa21e66756fb44c6c5680e725b1e3bc)

Signed-off-by: Jussi Kukkonen <jussi.kukkonen@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/flex/flex/CVE-2016-6354.patch

@@ -0,0 +1,59 @@
+From 3939eccdff598f47e5b37b05d58bf1b44d3796e7 Mon Sep 17 00:00:00 2001
+From: Jussi Kukkonen <jussi.kukkonen@intel.com>
+Date: Fri, 7 Oct 2016 14:15:38 +0300
+Subject: [PATCH] Prevent buffer overflow in yy_get_next_buffer
+
+This is upstream commit a5cbe929ac3255d371e698f62dc256afe7006466
+with some additional backporting to make binutils build again.
+
+Upstream-Status: Backport
+CVE: CVE-2016-6354
+Signed-off-by: Jussi Kukkonen <jussi.kukkonen@intel.com>
+---
+ src/flex.skl | 2 +-
+ src/scan.c   | 2 +-
+ src/skel.c   | 2 +-
+ 3 files changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/src/flex.skl b/src/flex.skl
+index ed71627..814d562 100644
+--- a/src/flex.skl
++++ b/src/flex.skl
+@@ -1718,7 +1718,7 @@ 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 )
+diff --git a/src/scan.c b/src/scan.c
+index f1dce75..1949872 100644
+--- a/src/scan.c
++++ b/src/scan.c
+@@ -4181,7 +4181,7 @@ static int yy_get_next_buffer (void)
+ 
+ 	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 )
+diff --git a/src/skel.c b/src/skel.c
+index 26cc889..0344d18 100644
+--- a/src/skel.c
++++ b/src/skel.c
+@@ -1929,7 +1929,7 @@ const char *skel[] = {
+   "",
+   "	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 )",
+-- 
+2.1.4
+

meta/recipes-devtools/flex/flex_2.6.0.bb

@@ -15,6 +15,7 @@ SRC_URI = "${SOURCEFORGE_MIRROR}/flex/flex-${PV}.tar.bz2 \
            file://do_not_create_pdf_doc.patch \
            file://0001-tests-add-a-target-for-building-tests-without-runnin.patch \
            file://0002-avoid-c-comments-in-c-code-fails-with-gcc-6.patch \
+           file://CVE-2016-6354.patch \
            ${@bb.utils.contains('PTEST_ENABLED', '1', '', 'file://disable-tests.patch', d)} \
            "