Re: [PATCH 3/7] module: rename __kstrtab_ns_* to __kstrtabns_* to avoid symbol conflict

[Matthias Maennich]

On Fri, Sep 27, 2019 at 06:35:59PM +0900, Masahiro Yamada wrote:
> The module namespace produces __strtab_ns_<sym> symbols to store
> namespace strings, but it does not guarantee the name uniqueness.
> This is a potential problem because we have exported symbols staring
> with "ns_".
>
> For example, kernel/capability.c exports the following symbols:
>
>  EXPORT_SYMBOL(ns_capable);
>  EXPORT_SYMBOL(capable);
>
> Assume a situation where those are converted as follows:
>
>  EXPORT_SYMBOL_NS(ns_capable, some_namespace);
>  EXPORT_SYMBOL_NS(capable, some_namespace);
>
> The former expands to "__kstrtab_ns_capable" and "__kstrtab_ns_ns_capable",
> and the latter to "__kstrtab_capable" and "__kstrtab_ns_capable".
> Then, we have the duplication for "__kstrtab_ns_capable".
>
> To ensure the uniqueness, rename "__kstrtab_ns_*" to "__kstrtabns_*".

Again, thanks for catching this!

Reviewed-by: Matthias Maennich <maennich@xxxxxxxxxx>

Cheers,
Matthias
> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> ---
>
> include/linux/export.h | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/export.h b/include/linux/export.h
> index 0695d4e847d9..621158ecd2e2 100644
> --- a/include/linux/export.h
> +++ b/include/linux/export.h
> @@ -55,7 +55,7 @@ extern struct module __this_module;
> 	    "__ksymtab_" #ns NS_SEPARATOR #sym ":		\n"	\
> 	    "	.long	" #sym "- .				\n"	\
> 	    "	.long	__kstrtab_" #sym "- .			\n"	\
> -	    "	.long	__kstrtab_ns_" #sym "- .		\n"	\
> +	    "	.long	__kstrtabns_" #sym "- .			\n"	\
> 	    "	.previous					\n")
>
> #define __KSYMTAB_ENTRY(sym, sec)					\
> @@ -79,7 +79,7 @@ struct kernel_symbol {
> 	asm("__ksymtab_" #ns NS_SEPARATOR #sym)				\
> 	__attribute__((section("___ksymtab" sec "+" #sym), used))	\
> 	__aligned(sizeof(void *))					\
> -	= { (unsigned long)&sym, __kstrtab_##sym, __kstrtab_ns_##sym }
> +	= { (unsigned long)&sym, __kstrtab_##sym, __kstrtabns_##sym }
>
> #define __KSYMTAB_ENTRY(sym, sec)					\
> 	static const struct kernel_symbol __ksymtab_##sym		\
> @@ -112,7 +112,7 @@ struct kernel_symbol {
> /* For every exported symbol, place a struct in the __ksymtab section */
> #define ___EXPORT_SYMBOL_NS(sym, sec, ns)				\
> 	___export_symbol_common(sym, sec);				\
> -	static const char __kstrtab_ns_##sym[]				\
> +	static const char __kstrtabns_##sym[]				\
> 	__attribute__((section("__ksymtab_strings"), used, aligned(1)))	\
> 	= #ns;								\
> 	__KSYMTAB_ENTRY_NS(sym, sec, ns)
> --
> 2.17.1