From: Ard Biesheuvel Date: Mon, 26 Jul 2021 14:31:44 +0000 (+0200) Subject: efi/libstub: arm64: Double check image alignment at entry X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c32ac11da3f83bb42b986702a9b92f0a14ed4182;p=linux.git efi/libstub: arm64: Double check image alignment at entry 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 --- diff --git a/drivers/firmware/efi/libstub/arm64-stub.c b/drivers/firmware/efi/libstub/arm64-stub.c index 010564f8bbc4e..2363fee9211c9 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;