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kern/efi/mm: Change to keep track of map allocation size

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Resolves: #RHEL-148310

Signed-off-by: Josue Hernandez <josherna@redhat.com>
This commit is contained in:
Josue Hernandez 2026-03-03 10:13:36 -06:00
parent e462386088
commit 1d3eeb3e18
3 changed files with 78 additions and 1 deletions
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72
0536-kern-efi-mm-Change-grub_efi_mm_add_regions-to-keep-t.patch Normal file
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@ -0,0 +1,72 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Mate Kukri <mate.kukri@canonical.com>
Date: Wed, 12 Jun 2024 16:10:49 +0100
Subject: [PATCH] kern/efi/mm: Change grub_efi_mm_add_regions() to keep track
of map allocation size
If the map was too big for the initial allocation, it was freed and replaced
with a bigger one, but the free call still used the hard-coded size.
Seems like this wasn't hit for a long time, because most firmware maps
fit into 12K.
This bug was triggered on Project Mu firmware with a big memory map, and
results in the heap getting trashed and the firmware ASSERTING on
corrupted heap guard values when GRUB exits.
Signed-off-by: Mate Kukri <mate.kukri@canonical.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/kern/efi/mm.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/grub-core/kern/efi/mm.c b/grub-core/kern/efi/mm.c
index b27e966e1..e31603c47 100644
--- a/grub-core/kern/efi/mm.c
+++ b/grub-core/kern/efi/mm.c
@@ -683,6 +683,7 @@ grub_efi_mm_add_regions (grub_size_t required_bytes, unsigned int flags)
grub_efi_memory_descriptor_t *memory_map_end;
grub_efi_memory_descriptor_t *filtered_memory_map;
grub_efi_memory_descriptor_t *filtered_memory_map_end;
+ grub_efi_uintn_t alloc_size;
grub_efi_uintn_t map_size;
grub_efi_uintn_t desc_size;
grub_err_t err;
@@ -691,7 +692,8 @@ grub_efi_mm_add_regions (grub_size_t required_bytes, unsigned int flags)
grub_nx_init ();
/* Prepare a memory region to store two memory maps. */
- memory_map = grub_efi_allocate_any_pages (2 * BYTES_TO_PAGES (MEMORY_MAP_SIZE));
+ alloc_size = 2 * BYTES_TO_PAGES (MEMORY_MAP_SIZE);
+ memory_map = grub_efi_allocate_any_pages (alloc_size);
if (! memory_map)
return grub_error (GRUB_ERR_OUT_OF_MEMORY, "cannot allocate memory for memory map");
@@ -702,14 +704,13 @@ grub_efi_mm_add_regions (grub_size_t required_bytes, unsigned int flags)
if (mm_status == 0)
{
- grub_efi_free_pages
- ((grub_efi_physical_address_t) ((grub_addr_t) memory_map),
- 2 * BYTES_TO_PAGES (MEMORY_MAP_SIZE));
+ grub_efi_free_pages ((grub_efi_physical_address_t)(grub_addr_t) memory_map, alloc_size);
/* Freeing/allocating operations may increase memory map size. */
map_size += desc_size * 32;
- memory_map = grub_efi_allocate_any_pages (2 * BYTES_TO_PAGES (map_size));
+ alloc_size = 2 * BYTES_TO_PAGES (map_size);
+ memory_map = grub_efi_allocate_any_pages (alloc_size);
if (! memory_map)
return grub_error (GRUB_ERR_OUT_OF_MEMORY, "cannot allocate memory for new memory map");
@@ -753,8 +754,7 @@ grub_efi_mm_add_regions (grub_size_t required_bytes, unsigned int flags)
#endif
/* Release the memory maps. */
- grub_efi_free_pages ((grub_addr_t) memory_map,
- 2 * BYTES_TO_PAGES (MEMORY_MAP_SIZE));
+ grub_efi_free_pages ((grub_efi_physical_address_t)(grub_addr_t) memory_map, alloc_size);
return GRUB_ERR_NONE;
}

1
grub.patches
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@ -532,3 +532,4 @@ Patch0532: 0532-commands-usbtest-Use-correct-string-length-field.patch
Patch0533: 0533-commands-usbtest-Ensure-string-length-is-sufficient-.patch
Patch0534: 0534-util-grub-mkimagexx-Stop-generating-unaligned-append.patch
Patch0535: 0535-grub-mkimage-Do-not-generate-empty-SBAT-metadata.patch
Patch0536: 0536-kern-efi-mm-Change-grub_efi_mm_add_regions-to-keep-t.patch

6
grub2.spec
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@ -16,7 +16,7 @@
Name: grub2
Epoch: 1
Version: 2.06
Release: 125%{?dist}
Release: 126%{?dist}
Summary: Bootloader with support for Linux, Multiboot and more
License: GPLv3+
URL: http://www.gnu.org/software/grub/
@ -543,6 +543,10 @@ fi
%endif
%changelog
* Mon Mar 09 2026 Josue Hernandez <josherna@redhat.com> 2.06-126
- kern/efi/mm: Change grub_efi_mm_add_regions() to keep track of map allocation size
- Resolves: #RHEL-148310
* Thu Mar 05 2026 Nicolas Frayer <nfrayer@redhat.com> 2.06-125
- ppc64le/sbat: Add an sbat CSV file for ppc64le
- Resolves: #RHEL-146555