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SubjectRe: [PATCH] Compile-time check re world-writeable module params

>One of mistakes module_param() user can make is to supply default value
>of module parameter as the last argument. module_param() accepts
>permissions instead. If default value is, say, 3 (-------wx), parameter
>becomes world-writeable.
>
>First version of this check (only "& 2" part) directly caught 4 out of 7
>places during my last grep.

It could probably do "& 0013" or "& ~664", because -x seems quite
useless in module parameters. That would also catch perm<0 and
perm>0777.

> #define __module_param_call(prefix, name, set, get, arg, perm) \
>+ /* Default value instead of permissions? */ \
>+ static int __param_perm_check_##name __attribute__((unused)) = \
>+ BUILD_BUG_ON_ZERO((perm) < 0 || (perm) > 0777 || ((perm) & 2)); \
> static char __param_str_##name[] = prefix #name; \
> static struct kernel_param const __param_##name \
> __attribute_used__ \


-`J'
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