[tip: efi/urgent] efi/x86: Fix boot regression on systems with invalid memmap entries

[tip-bot2 for Ard Biesheuvel]

The following commit has been merged into the efi/urgent branch of tip:

Commit-ID:     59365cadfbcd299b8cdbe0c165faf15767c5f166
Gitweb:        https://git.kernel.org/tip/59365cadfbcd299b8cdbe0c165faf15767c5f166
Author:        Ard Biesheuvel <ardb@xxxxxxxxxx>
AuthorDate:    Sun, 02 Feb 2020 00:33:04 +01:00
Committer:     Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Sun, 02 Feb 2020 10:25:43 +01:00

efi/x86: Fix boot regression on systems with invalid memmap entries

In efi_clean_memmap(), we do a pass over the EFI memory map to remove
bogus entries that may be returned on certain systems.

This recent commit:

  1db91035d01aa8bf ("efi: Add tracking for dynamically allocated memmaps")

refactored this code to pass the input to efi_memmap_install() via a
temporary struct on the stack, which is populated using an initializer
which inadvertently defines the value of its size field in terms of its
desc_size field, which value cannot be relied upon yet in the initializer
itself.

Fix this by using efi.memmap.desc_size instead, which is where we get
the value for desc_size from in the first place.

Reported-by: JÃrg Otte <jrg.otte@xxxxxxxxx>
Tested-by: JÃrg Otte <jrg.otte@xxxxxxxxx>
Tested-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: linux-efi@xxxxxxxxxxxxxxx
Cc: jrg.otte@xxxxxxxxx
Cc: torvalds@xxxxxxxxxxxxxxxxxxxx
Cc: mingo@xxxxxxxxxx
Link: https://lore.kernel.org/r/20200201233304.18322-1-ardb@xxxxxxxxxx
---
 arch/x86/platform/efi/efi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 59f7f6d..ae923ee 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -308,7 +308,7 @@ static void __init efi_clean_memmap(void)
 			.phys_map = efi.memmap.phys_map,
 			.desc_version = efi.memmap.desc_version,
 			.desc_size = efi.memmap.desc_size,
-			.size = data.desc_size * (efi.memmap.nr_map - n_removal),
+			.size = efi.memmap.desc_size * (efi.memmap.nr_map - n_removal),
 			.flags = 0,
 		};