Fix an out of memory error when loading large initrd images

Resolves: rhbz#1838633

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>

0219-x86-efi-Reduce-maximum-bounce-buffer-size-to-16-MiB.patch

@@ -0,0 +1,40 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Javier Martinez Canillas <javierm@redhat.com>
+Date: Tue, 26 May 2020 16:59:28 +0200
+Subject: [PATCH] x86-efi: Reduce maximum bounce buffer size to 16 MiB
+
+The EFI linux loader allocates a bounce buffer to copy the initrd since in
+some machines doing DMA on addresses above 4GB is not possible during EFI.
+
+But the verifiers framework also allocates a buffer to copy the initrd in
+its grub_file_open() handler. It does this since the data to verify has to
+be passed as a single chunk to modules that use the verifiers framework.
+
+If the initrd image size is big there may not be enough memory in the heap
+to allocate two buffers of that size. This causes an allocation failure in
+the verifiers framework and leads to the initrd not being read.
+
+To prevent these allocation failures, let's reduce the maximum size of the
+bounce buffer used in the EFI loader. Since the data read can be copied to
+the actual initrd address in multilple chunks.
+
+Resolves: rhbz#1838633
+
+Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
+---
+ grub-core/loader/i386/efi/linux.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
+index 50b7798d6e5..e5b2736b0ce 100644
+--- a/grub-core/loader/i386/efi/linux.c
++++ b/grub-core/loader/i386/efi/linux.c
+@@ -144,7 +144,7 @@ grub_linuxefi_unload (void)
+   return GRUB_ERR_NONE;
+ }
+ 
+-#define BOUNCE_BUFFER_MAX 0x10000000ull
++#define BOUNCE_BUFFER_MAX 0x1000000ull
+ 
+ static grub_ssize_t
+ read(grub_file_t file, grub_uint8_t *bufp, grub_size_t len)

grub.patches

@@ -216,3 +216,4 @@ Patch0215: 0215-10_linux.in-restore-existence-check-in-get_sorted_bl.patch
 Patch0216: 0216-tpm-Don-t-propagate-TPM-measurement-errors-to-the-ve.patch
 Patch0217: 0217-tpm-Enable-module-for-all-EFI-platforms.patch
 Patch0218: 0218-10_linux.in-Don-t-update-BLS-files-that-aren-t-manag.patch
+Patch0219: 0219-x86-efi-Reduce-maximum-bounce-buffer-size-to-16-MiB.patch

grub2.spec

@@ -9,7 +9,7 @@
 Name:		grub2
 Epoch:		1
 Version:	2.04
-Release:	21%{?dist}
+Release:	22%{?dist}
 Summary:	Bootloader with support for Linux, Multiboot and more
 License:	GPLv3+
 URL:		http://www.gnu.org/software/grub/
@@ -504,6 +504,10 @@ rm -r /boot/grub2.tmp/ || :
 %endif
 
 %changelog
+* Tue May 26 2020 Javier Martinez Canillas <javierm@redhat.com> - 2.04-22
+- Fix an out of memory error when loading large initrd images
+  Resolves: rhbz#1838633
+
 * Wed May 20 2020 Javier Martinez Canillas <javierm@redhat.com> - 2.04-21
 - Don't update BLS files that aren't managed by GRUB scripts
   Resolves: rhbz#1837783