From 325f5585ec36953a3fe2e000451f690440fe1bf5 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 26 Jun 2020 17:58:32 +0200 Subject: [PATCH] arm64/acpi: disallow writeable AML opregion mapping for EFI code regions Given that the contents of EFI runtime code and data regions are provided by the firmware, as well as the DSDT, it is not unimaginable that AML code exists today that accesses EFI runtime code regions using a SystemMemory OpRegion. There is nothing fundamentally wrong with that, but since we take great care to ensure that executable code is never mapped writeable and executable at the same time, we should not permit AML to create writable mapping. Signed-off-by: Ard Biesheuvel Acked-by: Lorenzo Pieralisi Link: https://lore.kernel.org/r/20200626155832.2323789-3-ardb@kernel.org Signed-off-by: Catalin Marinas --- arch/arm64/kernel/acpi.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index 01b861e225b0..455966401102 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -301,6 +301,15 @@ void __iomem *acpi_os_ioremap(acpi_physical_address phys, acpi_size size) pr_warn(FW_BUG "requested region covers kernel memory @ %pa\n", &phys); return NULL; + case EFI_RUNTIME_SERVICES_CODE: + /* + * This would be unusual, but not problematic per se, + * as long as we take care not to create a writable + * mapping for executable code. + */ + prot = PAGE_KERNEL_RO; + break; + case EFI_ACPI_RECLAIM_MEMORY: /* * ACPI reclaim memory is used to pass firmware tables