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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Javier Martinez Canillas <javierm@redhat.com>
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Date: Tue, 26 May 2020 16:59:28 +0200
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Subject: [PATCH] x86-efi: Reduce maximum bounce buffer size to 16 MiB
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The EFI linux loader allocates a bounce buffer to copy the initrd since in
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some machines doing DMA on addresses above 4GB is not possible during EFI.
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But the verifiers framework also allocates a buffer to copy the initrd in
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its grub_file_open() handler. It does this since the data to verify has to
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be passed as a single chunk to modules that use the verifiers framework.
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If the initrd image size is big there may not be enough memory in the heap
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to allocate two buffers of that size. This causes an allocation failure in
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the verifiers framework and leads to the initrd not being read.
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To prevent these allocation failures, let's reduce the maximum size of the
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bounce buffer used in the EFI loader. Since the data read can be copied to
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the actual initrd address in multilple chunks.
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Resolves: rhbz#1838633
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Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
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(cherry picked from commit 1c0d2ebdddf69962395f0fa4578446654512f3c4)
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---
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grub-core/loader/i386/efi/linux.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/grub-core/loader/i386/efi/linux.c b/grub-core/loader/i386/efi/linux.c
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index e9d2c85b3..a043df891 100644
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--- a/grub-core/loader/i386/efi/linux.c
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+++ b/grub-core/loader/i386/efi/linux.c
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@@ -146,7 +146,7 @@ grub_linuxefi_unload (void)
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return GRUB_ERR_NONE;
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}
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-#define BOUNCE_BUFFER_MAX 0x10000000ull
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+#define BOUNCE_BUFFER_MAX 0x1000000ull
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static grub_ssize_t
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read(grub_file_t file, grub_uint8_t *bufp, grub_size_t len)
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