linux-kernel - Re: [PATCH] kbuild: Strip trailing padding bytes from modules.builtin.modinfo

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Message-ID: <aQxGziZq6yK-V8HC@derry.ads.avm.de>
Date: Thu, 6 Nov 2025 07:57:18 +0100
From: Nicolas Schier <nsc@...nel.org>
To: Nathan Chancellor <nathan@...nel.org>
Cc: Dimitri John Ledkov <dimitri.ledkov@...gut.co.uk>,
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org, Omar Sandoval <osandov@...com>,
	Samir M <samir@...ux.ibm.com>,
	Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
Subject: Re: [PATCH] kbuild: Strip trailing padding bytes from
 modules.builtin.modinfo

On Wed, Nov 05, 2025 at 03:30:27PM -0700, Nathan Chancellor wrote:
> After commit d50f21091358 ("kbuild: align modinfo section for Secureboot
> Authenticode EDK2 compat"), running modules_install with certain
> versions of kmod (such as 29.1 in Ubuntu Jammy) in certain
> configurations may fail with:
> 
>   depmod: ERROR: kmod_builtin_iter_next: unexpected string without modname prefix
> 
> The additional padding bytes to ensure .modinfo is aligned within
> vmlinux.unstripped are unexpected by kmod, as this section has always
> just been null-terminated strings.
> 
> Strip the trailing padding bytes from modules.builtin.modinfo after it
> has been extracted from vmlinux.unstripped to restore the format that
> kmod expects while keeping .modinfo aligned within vmlinux.unstripped to
> avoid regressing the Authenticode calculation fix for EDK2.
> 
> Cc: stable@...r.kernel.org
> Fixes: d50f21091358 ("kbuild: align modinfo section for Secureboot Authenticode EDK2 compat")
> Reported-by: Omar Sandoval <osandov@...com>
> Reported-by: Samir M <samir@...ux.ibm.com>
> Reported-by: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
> Closes: https://lore.kernel.org/7fef7507-ad64-4e51-9bb8-c9fb6532e51e@linux.ibm.com/
> Tested-by: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
> Tested-by: Omar Sandoval <osandov@...com>
> Signed-off-by: Nathan Chancellor <nathan@...nel.org>
> ---
>  scripts/Makefile.vmlinux | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 

Reviewed-by: Nicolas Schier <nsc@...nel.org>

-- 
Nicolas