flex: Add CVE-2019-6293 to exclusions for checks

CVE is effectively disputed - yes there is stack exhaustion but no bug and it
is building the parser, not running it, effectively similar to a compiler ICE.
Upstream no plans to address and there is no security issue.

westes/flex#414

(From OE-Core rev: b939b005b06be58a276d565f755ee2d8f3e5dfc1)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 0cae5d7a24bedf6784781b62cbb3795a44bab4d1)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/distro/include/cve-extra-exclusions.inc

@@ -61,10 +61,6 @@ CVE_CHECK_WHITELIST += "CVE-2020-29509 CVE-2020-29511"
 # There was a proposed patch https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg06098.html
 # however qemu maintainers are sure the patch is incorrect and should not be applied.
 
-# flex:flex-native https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2019-6293
-# Upstream bug, still open: https://github.com/westes/flex/issues/414
-# Causes memory exhaustion so potential DoS but no buffer overflow, low priority
-
 # wget https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-31879
 # https://mail.gnu.org/archive/html/bug-wget/2021-02/msg00002.html
 # No response upstream as of 2021/5/12

meta/recipes-devtools/flex/flex_2.6.4.bb

@@ -26,6 +26,11 @@ SRC_URI[sha256sum] = "e87aae032bf07c26f85ac0ed3250998c37621d95f8bd748b31f15b33c4
 UPSTREAM_CHECK_URI = "https://github.com/westes/flex/releases"
 UPSTREAM_CHECK_REGEX = "flex-(?P<pver>\d+(\.\d+)+)\.tar"
 
+# Disputed - yes there is stack exhaustion but no bug and it is building the
+# parser, not running it, effectively similar to a compiler ICE. Upstream no plans to address
+# https://github.com/westes/flex/issues/414
+CVE_CHECK_WHITELIST += "CVE-2019-6293"
+
 inherit autotools gettext texinfo ptest
 
 M4 = "${bindir}/m4"