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efi: Replace efi_memory_attributes_table_t 0-sized array with flexible array

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While efi_memory_attributes_table_t::entry isn't used directly as an
array, it is used as a base for pointer arithmetic. The type is wrong
as it's not technically an array of efi_memory_desc_t's; they could be
larger. Regardless, leave the type unchanged and remove the old style
"0" array size. Additionally replace the open-coded entry offset code
with the existing efi_memdesc_ptr() helper.

Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Kees Cook 2024-07-11 10:11:13 -07:00 committed by Ard Biesheuvel
parent 887c4cf559
commit 4a2ebb0822
2 changed files with 6 additions and 2 deletions
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2
drivers/firmware/efi/memattr.c
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@ -164,7 +164,7 @@ int __init efi_memattr_apply_permissions(struct mm_struct *mm,
bool valid;
char buf[64];
valid = entry_is_valid((void *)tbl->entry + i * tbl->desc_size,
valid = entry_is_valid(efi_memdesc_ptr(tbl->entry, tbl->desc_size, i),
&md);
size = md.num_pages << EFI_PAGE_SHIFT;
if (efi_enabled(EFI_DBG) || !valid)

6
include/linux/efi.h
View File

@ -608,7 +608,11 @@ typedef struct {
u32 num_entries;
u32 desc_size;
u32 flags;
efi_memory_desc_t entry[0];
/*
* There are @num_entries following, each of size @desc_size bytes,
* including an efi_memory_desc_t header. See efi_memdesc_ptr().
*/
efi_memory_desc_t entry[];
} efi_memory_attributes_table_t;
typedef struct {