fix BootHole

https://www.openwall.com/lists/oss-security/2020/07/29/3
https://lists.gnu.org/archive/html/grub-devel/2020-07/msg00034.html

Extracted the changes from Debian's grub git repository, with
minor modifications:

https://salsa.debian.org/grub-team/grub

PKGBUILD

@@ -21,10 +21,10 @@ _UNIFONT_VER="13.0.02"
 
 pkgname='grub'
 pkgdesc='GNU GRand Unified Bootloader (2)'
+epoch=2
 _pkgver=2.04
 pkgver=${_pkgver/-/}
-pkgrel=7
-epoch=2
+pkgrel=8
 url='https://www.gnu.org/software/grub/'
 arch=('x86_64')
 license=('GPL3')
@@ -65,6 +65,7 @@ source=("git+https://git.savannah.gnu.org/git/grub.git#tag=grub-${_pkgver}?signe
         '0003-10_linux-detect-archlinux-initramfs.patch'
         '0004-add-GRUB_COLOR_variables.patch'
         '0005-grub-install-fix-inverted-test-for-NLS-enabled-when-.patch'
+        '0006-BootHole.patch'
         'grub.default')
 
 sha256sums=('SKIP'
@@ -75,6 +76,7 @@ sha256sums=('SKIP'
             '171415ab075d1ac806f36c454feeb060f870416f24279b70104bba94bd6076d4'
             'a5198267ceb04dceb6d2ea7800281a42b3f91fd02da55d2cc9ea20d47273ca29'
             '06820004912a3db195a76e68b376fce1ba6507ac740129f0b99257ef07aba1ea'
+            '55c559b6d8c4a832a43cc35c7635de37402ec9e3e3bfd8b2b7761a06f0bfda02'
             '690adb7943ee9fedff578a9d482233925ca3ad3e5a50fffddd27cf33300a89e3')
 
 _backports=(
@@ -125,6 +127,9 @@ prepare() {
 	echo "Patch to NLS installation..."
 	patch -Np1 -i "${srcdir}/0005-grub-install-fix-inverted-test-for-NLS-enabled-when-.patch"
 
+	echo "Patch BootHole..."
+	patch -Np1 -i "${srcdir}/0006-BootHole.patch"
+
 	echo "Fix DejaVuSans.ttf location so that grub-mkfont can create *.pf2 files for starfield theme..."
 	sed 's|/usr/share/fonts/dejavu|/usr/share/fonts/dejavu /usr/share/fonts/TTF|g' -i "configure.ac"