| From c00b413a96261faef4ce22329153c6abd4acef25 Mon Sep 17 00:00:00 2001 |
| From: Ard Biesheuvel <ardb@kernel.org> |
| Date: Thu, 6 Mar 2025 16:59:16 +0100 |
| Subject: x86/boot: Sanitize boot params before parsing command line |
| |
| From: Ard Biesheuvel <ardb@kernel.org> |
| |
| commit c00b413a96261faef4ce22329153c6abd4acef25 upstream. |
| |
| The 5-level paging code parses the command line to look for the 'no5lvl' |
| string, and does so very early, before sanitize_boot_params() has been |
| called and has been given the opportunity to wipe bogus data from the |
| fields in boot_params that are not covered by struct setup_header, and |
| are therefore supposed to be initialized to zero by the bootloader. |
| |
| This triggers an early boot crash when using syslinux-efi to boot a |
| recent kernel built with CONFIG_X86_5LEVEL=y and CONFIG_EFI_STUB=n, as |
| the 0xff padding that now fills the unused PE/COFF header is copied into |
| boot_params by the bootloader, and interpreted as the top half of the |
| command line pointer. |
| |
| Fix this by sanitizing the boot_params before use. Note that there is no |
| harm in calling this more than once; subsequent invocations are able to |
| spot that the boot_params have already been cleaned up. |
| |
| Signed-off-by: Ard Biesheuvel <ardb@kernel.org> |
| Signed-off-by: Ingo Molnar <mingo@kernel.org> |
| Cc: "H. Peter Anvin" <hpa@zytor.com> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: <stable@vger.kernel.org> # v6.1+ |
| Link: https://lore.kernel.org/r/20250306155915.342465-2-ardb+git@google.com |
| Closes: https://lore.kernel.org/all/202503041549.35913.ulrich.gemkow@ikr.uni-stuttgart.de |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/x86/boot/compressed/pgtable_64.c | 2 ++ |
| 1 file changed, 2 insertions(+) |
| |
| --- a/arch/x86/boot/compressed/pgtable_64.c |
| +++ b/arch/x86/boot/compressed/pgtable_64.c |
| @@ -1,6 +1,7 @@ |
| // SPDX-License-Identifier: GPL-2.0 |
| #include "misc.h" |
| #include <asm/bootparam.h> |
| +#include <asm/bootparam_utils.h> |
| #include <asm/e820/types.h> |
| #include <asm/processor.h> |
| #include "pgtable.h" |
| @@ -107,6 +108,7 @@ asmlinkage void configure_5level_paging( |
| bool l5_required = false; |
| |
| /* Initialize boot_params. Required for cmdline_find_option_bool(). */ |
| + sanitize_boot_params(bp); |
| boot_params_ptr = bp; |
| |
| /* |
