[PATCH] module: fix clang CFI with MODULE_UNLOAD=n

[PATCH] module: fix clang CFI with MODULE_UNLOAD=n

[Arnd Bergmann]

From: Arnd Bergmann <arnd@arndb.de>

When CONFIG_MODULE_UNLOAD is disabled, the module->exit member
is not defined, causing a build failure:

kernel/module.c:4493:8: error: no member named 'exit' in 'struct module'
                mod->exit = *exit;

add an #ifdef block around this.

Fixes: cf68fffb66d6 ("add support for Clang CFI")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 kernel/module.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/module.c b/kernel/module.c
index 40ec9a030eec..5c26a76e800b 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -4489,8 +4489,10 @@ static void cfi_init(struct module *mod)
 	/* Fix init/exit functions to point to the CFI jump table */
 	if (init)
 		mod->init = *init;
+#ifdef CONFIG_MODULE_UNLOAD
 	if (exit)
 		mod->exit = *exit;
+#endif
 
 	cfi_module_add(mod, module_addr_min);
 #endif
-- 
2.29.2

Re: [PATCH] module: fix clang CFI with MODULE_UNLOAD=n

[Miroslav Benes]

On Mon, 27 Sep 2021, Arnd Bergmann wrote:

> From: Arnd Bergmann <arnd@arndb.de>
> 
> When CONFIG_MODULE_UNLOAD is disabled, the module->exit member
> is not defined, causing a build failure:
> 
> kernel/module.c:4493:8: error: no member named 'exit' in 'struct module'
>                 mod->exit = *exit;
> 
> add an #ifdef block around this.
> 
> Fixes: cf68fffb66d6 ("add support for Clang CFI")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Reviewed-by: Miroslav Benes <mbenes@suse.cz>

M

Re: [PATCH] module: fix clang CFI with MODULE_UNLOAD=n

[Sami Tolvanen]

Hi Arnd,

On Mon, Sep 27, 2021 at 5:15 AM Arnd Bergmann <arnd@kernel.org> wrote:
>
> From: Arnd Bergmann <arnd@arndb.de>
>
> When CONFIG_MODULE_UNLOAD is disabled, the module->exit member
> is not defined, causing a build failure:
>
> kernel/module.c:4493:8: error: no member named 'exit' in 'struct module'
>                 mod->exit = *exit;
>
> add an #ifdef block around this.
>
> Fixes: cf68fffb66d6 ("add support for Clang CFI")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  kernel/module.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index 40ec9a030eec..5c26a76e800b 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -4489,8 +4489,10 @@ static void cfi_init(struct module *mod)
>         /* Fix init/exit functions to point to the CFI jump table */
>         if (init)
>                 mod->init = *init;
> +#ifdef CONFIG_MODULE_UNLOAD
>         if (exit)
>                 mod->exit = *exit;
> +#endif
>
>         cfi_module_add(mod, module_addr_min);
>  #endif

Thanks for the fix!

Reviewed-by: Sami Tolvanen <samitolvanen@google.com>

Sami

Re: [PATCH] module: fix clang CFI with MODULE_UNLOAD=n

[Kees Cook]

On Mon, Sep 27, 2021 at 02:15:10PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> When CONFIG_MODULE_UNLOAD is disabled, the module->exit member
> is not defined, causing a build failure:
> 
> kernel/module.c:4493:8: error: no member named 'exit' in 'struct module'
>                 mod->exit = *exit;
> 
> add an #ifdef block around this.
> 
> Fixes: cf68fffb66d6 ("add support for Clang CFI")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Nice catch; thanks! (Not a lot of config build that way it seems...)

Acked-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH] module: fix clang CFI with MODULE_UNLOAD=n

[Jessica Yu]

+++ Arnd Bergmann [27/09/21 14:15 +0200]:
>From: Arnd Bergmann <arnd@arndb.de>
>
>When CONFIG_MODULE_UNLOAD is disabled, the module->exit member
>is not defined, causing a build failure:
>
>kernel/module.c:4493:8: error: no member named 'exit' in 'struct module'
>                mod->exit = *exit;
>
>add an #ifdef block around this.
>
>Fixes: cf68fffb66d6 ("add support for Clang CFI")
>Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Applied, thanks everyone!

Jessica