On 09.08.23 15:58, 'Earl Chew' via EFI Boot Guard wrote:
> When building for 32 bit architectures, casting from
> 64 bit EFI_PHYSICAL_ADDRESS to 32 bit VOID * elicits a
> compiler warning (-Wint-to-pointer-cast).
>
> Check that the cast will not drop high order bits by using
> uintptr_t as an intermediate type to transform the address
> quietly.
>
> Signed-off-by: Earl Chew <[email protected]>
> ---
> kernel-stub/main.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/kernel-stub/main.c b/kernel-stub/main.c
> index c0be1f6..c2e9482 100644
> --- a/kernel-stub/main.c
> +++ b/kernel-stub/main.c
> @@ -104,6 +104,7 @@ EFI_STATUS efi_main(EFI_HANDLE image_handle,
> EFI_SYSTEM_TABLE *system_table)
> BOOLEAN has_dtbs = FALSE;
> const VOID *kernel_source;
> EFI_PHYSICAL_ADDRESS kernel_buffer;
> + EFI_PHYSICAL_ADDRESS aligned_kernel_buffer;
> const CHAR8 *fdt_compatible;
> VOID *fdt, *alt_fdt = NULL;
> EFI_IMAGE_ENTRY_POINT kernel_entry;
> @@ -193,10 +194,16 @@ EFI_STATUS efi_main(EFI_HANDLE image_handle,
> EFI_SYSTEM_TABLE *system_table)
> goto cleanup_initrd;
> }
>
> - kernel_image.ImageBase = (VOID *)
> - align_addr(kernel_buffer, pe_header->Opt.SectionAlignment);
> + aligned_kernel_buffer = align_addr(kernel_buffer,
> pe_header->Opt.SectionAlignment);
> +
Let's not change the wrapping here.
> + kernel_image.ImageBase = (VOID *) (uintptr_t) aligned_kernel_buffer;
> kernel_image.ImageSize = kernel_section->VirtualSize;
>
> + if ((uintptr_t) kernel_image.ImageBase != aligned_kernel_buffer) {
How about testing this right after obtaining aligned_kernel_buffer,
checking weather for "(uintptr_t) aligned_kernel_buffer !=
aligned_kernel_buffer"?
> + error(L"Error aligning memory for kernel image",
> EFI_LOAD_ERROR);
"Overflow while aligning kernel image"?
> + goto cleanup_buffer;
> + }
> +
> CopyMem(kernel_image.ImageBase, kernel_source, kernel_image.ImageSize);
> /* Clear the rest so that .bss is definitely zero. */
> SetMem((UINT8 *) kernel_image.ImageBase + kernel_image.ImageSize,
Good catch. We are missing -Werror, and no one has actually reading this:
https://github.com/siemens/efibootguard/actions/runs/5809411513/job/15748132394
Means also that there are more issues.
Jan
--
Siemens AG, Technology
Linux Expert Center
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