linux-kernel - Re: [PATCH 3/7] module: rename __kstrtab_ns_* to __kstrtabns

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Message-ID: <20190927121457.GC259443@google.com>
Date:   Fri, 27 Sep 2019 13:14:57 +0100
From:   Matthias Maennich <maennich@...gle.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Jessica Yu <jeyu@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Martijn Coenen <maco@...roid.com>,
        Will Deacon <will.deacon@....com>,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/7] module: rename __kstrtab_ns_* to __kstrtabns_* to
 avoid symbol conflict

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@...gle.com>

Cheers,
Matthias
>Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
>---
>
> 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
>