On 30/06/2025 16.32, Petr Pavlu wrote:
> The moduleparam code allows modules to provide their own definition of
> MODULE_PARAM_PREFIX, instead of using the default KBUILD_MODNAME ".".
>
> Commit 730b69d22525 ("module: check kernel param length at compile time,
> not runtime") added a check to ensure the prefix doesn't exceed
> MODULE_NAME_LEN, as this is what param_sysfs_builtin() expects.
>
> Later, commit 58f86cc89c33 ("VERIFY_OCTAL_PERMISSIONS: stricter checking
> for sysfs perms.") removed this check, but there is no indication this was
> intentional.
>
> Since the check is still useful for param_sysfs_builtin() to function
> properly, reintroduce it in __module_param_call(), but in a modernized form
> using static_assert().
>
> While here, clean up the __module_param_call() comments. In particular,
> remove the comment "Default value instead of permissions?", which comes
> from commit 9774a1f54f17 ("[PATCH] Compile-time check re world-writeable
> module params"). This comment was related to the test variable
> __param_perm_check_##name, which was removed in the previously mentioned
> commit 58f86cc89c33.
>
> Fixes: 58f86cc89c33 ("VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs
> perms.")
> Signed-off-by: Petr Pavlu <petr.pa...@suse.com>
> ---
> include/linux/moduleparam.h | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h
> index bfb85fd13e1f..110e9d09de24 100644
> --- a/include/linux/moduleparam.h
> +++ b/include/linux/moduleparam.h
> @@ -282,10 +282,9 @@ struct kparam_array
> #define __moduleparam_const const
> #endif
>
> -/* This is the fundamental function for registering boot/module
> - parameters. */
> +/* This is the fundamental function for registering boot/module parameters.
> */
> #define __module_param_call(prefix, name, ops, arg, perm, level, flags)
> \
> - /* Default value instead of permissions? */ \
> + static_assert(sizeof(""prefix) - 1 <= MAX_PARAM_PREFIX_LEN); \
Can you clarify if -1 to remove the dot from prefix?
Final code
static_assert(sizeof(""prefix) - 1 <= __MODULE_NAME_LEN); \
with __MODULE_NAME_LEN being:
#define __MODULE_NAME_LEN (64 - sizeof(unsigned long))
> static const char __param_str_##name[] = prefix #name; \
> static struct kernel_param __moduleparam_const __param_##name \
> __used __section("__param") \
