linux-kernel - Re: [PATCH v2 3/4] module: centralize no-versions force load check

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Message-ID: <14e0f072-59e6-4657-8ab1-fe1fbc30ac43@suse.com>
Date: Tue, 26 Aug 2025 11:40:39 +0200
From: Petr Pavlu <petr.pavlu@...e.com>
To: Jinchao Wang <wangjinchao600@...il.com>
Cc: Luis Chamberlain <mcgrof@...nel.org>, Daniel Gomez <da.gomez@...nel.org>,
 Sami Tolvanen <samitolvanen@...gle.com>, linux-modules@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] module: centralize no-versions force load check

On 8/25/25 11:15 AM, Jinchao Wang wrote:
> Move try_to_force_load() call from check_version() to
> check_modstruct_version() to handle "no versions" case only once before
> other version checks.
> 
> This prevents duplicate force load attempts and makes the error message
> show the proper reason.
> 
> Signed-off-by: Jinchao Wang <wangjinchao600@...il.com>
> ---
>  kernel/module/version.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/module/version.c b/kernel/module/version.c
> index 2beefeba82d9..3f07fd03cb30 100644
> --- a/kernel/module/version.c
> +++ b/kernel/module/version.c
> @@ -41,10 +41,6 @@ int check_version(const struct load_info *info,
>  		return 1;
>  	}
>  
> -	/* No versions at all?  modprobe --force does this. */
> -	if (versindex == 0)
> -		return try_to_force_load(mod, symname) == 0;
> -
>  	versions = (void *)sechdrs[versindex].sh_addr;
>  	num_versions = sechdrs[versindex].sh_size
>  		/ sizeof(struct modversion_info);

Removing this return completely means that when versindex == 0, the
function incorrectly looks at the dummy section #0 and eventually
calls pr_warn_once("%s: no symbol version for %s\n", ...).

As I outlined in my prototype patch previously [1], I think this should
be changed to:

	/* No versions? Ok, already tainted in check_modstruct_version(). */
	if (versindex == 0)
		return 1;

> @@ -81,6 +77,11 @@ int check_modstruct_version(const struct load_info *info,
>  	};
>  	bool have_symbol;
>  
> +	/* No versions at all?  modprobe --force does this. */
> +	if (info->index.vers == 0 &&
> +	    try_to_force_load(mod, "no versions module"))
> +		return 1;
> +
>  	/*
>  	 * Since this should be found in kernel (which can't be removed), no
>  	 * locking is necessary. Regardless use a RCU read section to keep

I suggest that the reason message should say "no versions for imported
symbols" to indicate which version data is missing and to be consistent
with check_export_symbol_versions(), which uses "no versions for
exported symbols".

[1] https://lore.kernel.org/linux-modules/3992b57d-3d8b-4d60-bc4a-f227f712dcca@suse.com/

-- 
Thanks,
Petr