From b636a0d1e5c8431b2a7d284f415835c917d1ee2d Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Mon, 26 Jul 2021 16:31:44 +0200 Subject: [PATCH] efi/libstub: arm64: Double check image alignment at entry commit c32ac11da3f83bb42b986702a9b92f0a14ed4182 upstream. On arm64, the stub only moves the kernel image around in memory if needed, which is typically only for KASLR, given that relocatable kernels (which is the default) can run from any 64k aligned address, which is also the minimum alignment communicated to EFI via the PE/COFF header. Unfortunately, some loaders appear to ignore this header, and load the kernel at some arbitrary offset in memory. We can deal with this, but let's check for this condition anyway, so non-compliant code can be spotted and fixed. Cc: # v5.10+ Signed-off-by: Ard Biesheuvel Tested-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- drivers/firmware/efi/libstub/arm64-stub.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 6f214c9c303e..da0252a4c369 100644 --- a/drivers/firmware/efi/libstub/arm64-stub.c +++ b/drivers/firmware/efi/libstub/arm64-stub.c @@ -119,6 +119,10 @@ efi_status_t handle_kernel_image(unsigned long *image_addr, if (image->image_base != _text) efi_err("FIRMWARE BUG: efi_loaded_image_t::image_base has bogus value\n"); + if (!IS_ALIGNED((u64)_text, EFI_KIMG_ALIGN)) + efi_err("FIRMWARE BUG: kernel image not aligned on %ldk boundary\n", + EFI_KIMG_ALIGN >> 10); + kernel_size = _edata - _text; kernel_memsize = kernel_size + (_end - _edata); *reserve_size = kernel_memsize; -- 2.43.0