grub2/SOURCES/0298-mm-Assert-that-we-preserve-header-vs-region-alignmen.patch

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2023-04-11 14:25:15 +00:00
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Thu, 21 Apr 2022 15:24:14 +1000
Subject: [PATCH] mm: Assert that we preserve header vs region alignment
grub_mm_region_init() does:
h = (grub_mm_header_t) (r + 1);
where h is a grub_mm_header_t and r is a grub_mm_region_t.
Cells are supposed to be GRUB_MM_ALIGN aligned, but while grub_mm_dump
ensures this vs the region header, grub_mm_region_init() does not.
It's better to be explicit than implicit here: rather than changing
grub_mm_region_init() to ALIGN_UP(), require that the struct is
explicitly a multiple of the header size.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Patrick Steinhardt <ps@pks.im>
(cherry picked from commit 1df8fe66c57087eb33bd6dc69f786ed124615aa7)
---
include/grub/mm_private.h | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/include/grub/mm_private.h b/include/grub/mm_private.h
index 203533cc3d..a688b92a83 100644
--- a/include/grub/mm_private.h
+++ b/include/grub/mm_private.h
@@ -20,6 +20,7 @@
#define GRUB_MM_PRIVATE_H 1
#include <grub/mm.h>
+#include <grub/misc.h>
/* For context, see kern/mm.c */
@@ -89,4 +90,17 @@ typedef struct grub_mm_region
extern grub_mm_region_t EXPORT_VAR (grub_mm_base);
#endif
+static inline void
+grub_mm_size_sanity_check (void) {
+ /* Ensure we preserve alignment when doing h = (grub_mm_header_t) (r + 1). */
+ COMPILE_TIME_ASSERT ((sizeof (struct grub_mm_region) %
+ sizeof (struct grub_mm_header)) == 0);
+
+ /*
+ * GRUB_MM_ALIGN is supposed to represent cell size, and a mm_header is
+ * supposed to be 1 cell.
+ */
+ COMPILE_TIME_ASSERT (sizeof (struct grub_mm_header) == GRUB_MM_ALIGN);
+}
+
#endif