From: Tom Lendacky thomas.lendacky@amd.com
commit 1ff2fc02862d52e18fd3daabcfe840ec27e920a8 upstream.
Reserving memory using efi_mem_reserve() calls into the x86 efi_arch_mem_reserve() function. This function will insert a new EFI memory descriptor into the EFI memory map representing the area of memory to be reserved and marking it as EFI runtime memory. As part of adding this new entry, a new EFI memory map is allocated and mapped. The mapping is where a problem can occur. This new memory map is mapped using early_memremap() and generally mapped encrypted, unless the new memory for the mapping happens to come from an area of memory that is marked as EFI_BOOT_SERVICES_DATA memory. In this case, the new memory will be mapped unencrypted. However, during replacement of the old memory map, efi_mem_type() is disabled, so the new memory map will now be long-term mapped encrypted (in efi.memmap), resulting in the map containing invalid data and causing the kernel boot to crash.
Since it is known that the area will be mapped encrypted going forward, explicitly map the new memory map as encrypted using early_memremap_prot().
Cc: stable@vger.kernel.org # 4.14.x Fixes: 8f716c9b5feb ("x86/mm: Add support to access boot related data in the clear") Link: https://lore.kernel.org/all/ebf1eb2940405438a09d51d121ec0d02c8755558.1634752... Signed-off-by: Tom Lendacky thomas.lendacky@amd.com [ardb: incorporate Kconfig fix by Arnd] Signed-off-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/Kconfig | 1 + arch/x86/platform/efi/quirks.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1990,6 +1990,7 @@ config EFI depends on ACPI select UCS2_STRING select EFI_RUNTIME_WRAPPERS + select ARCH_USE_MEMREMAP_PROT ---help--- This enables the kernel to use EFI runtime services that are available (such as the EFI variable services). --- a/arch/x86/platform/efi/quirks.c +++ b/arch/x86/platform/efi/quirks.c @@ -279,7 +279,8 @@ void __init efi_arch_mem_reserve(phys_ad return; }
- new = early_memremap(new_phys, new_size); + new = early_memremap_prot(new_phys, new_size, + pgprot_val(pgprot_encrypted(FIXMAP_PAGE_NORMAL))); if (!new) { pr_err("Failed to map new boot services memmap\n"); return;