Re: [PATCH v2] gpiolib: annotate struct acpi_gpio_mapping with __counted_by_ptr

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] efi/libstub: incomplete removal of __counted_by attribute
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commit db43ca0ac71b2e4fee34adfbd304bb5744b340e2
Author: Bill Wendling <morbo@google.com>

gpiolib: annotate struct acpi_gpio_mapping with __counted_by_ptr

This commit annotates the data pointer in struct acpi_gpio_mapping with the
__counted_by_ptr attribute to improve bounds checking. It also undefines the
__counted_by and __counted_by_ptr macros in some of the EFI stub library
source files to prevent unsupported bounds-checking instrumentation that could
crash the boot firmware.

> diff --git a/drivers/firmware/efi/libstub/alignedmem.c b/drivers/firmware/efi/libstub/alignedmem.c
> index 31928bd87e0ff..36248a13f15b4 100644
> --- a/drivers/firmware/efi/libstub/alignedmem.c
> +++ b/drivers/firmware/efi/libstub/alignedmem.c
> @@ -1,5 +1,13 @@
>  // SPDX-License-Identifier: GPL-2.0
>  
> +/*
> + * The EFI stub doesn't execute in the context of the kernel, only in the
> + * context of boot firmware, which isn't the time or place to crash the kernel.
> + * Therefore, disable the __counted_by__ attribute.
> + */
> +#undef __counted_by
> +#undef __counted_by_ptr

[Severity: High]
Are there other EFI stub library files that need these attributes disabled?

The #undef directives appear to be applied to only 14 out of 45 source files
in drivers/firmware/efi/libstub/. Architecture-specific EFI stub files for
non-x86 platforms (e.g., drivers/firmware/efi/libstub/arm64-stub.c,
drivers/firmware/efi/libstub/riscv-stub.c) and generic core files
(e.g., drivers/firmware/efi/libstub/vsprintf.c, drivers/firmware/efi/libstub/fdt.c, 
drivers/firmware/efi/libstub/zboot.c) were not updated.

These files still include <linux/efi.h>, which ultimately pulls in
<linux/compiler_attributes.h> and defines the macros globally. Compiling the
EFI stub for non-x86 architectures or enabling generic features like zboot
could leave the unsupported annotations active, potentially causing build
errors or fatal boot-time panics.

Could this be solved by passing -U__counted_by and -U__counted_by_ptr via
KBUILD_CFLAGS in drivers/firmware/efi/libstub/Makefile, or by adding the
directives to a common header like efistub.h?

> +
>  #include <linux/efi.h>
>  #include <asm/efi.h>

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Sashiko AI review · https://sashiko.dev/#/patchset/20261002124226.435265-1-morbo@google.com?part=1