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

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

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

Hi Arnd,

On Mon, Sep 27, 2021 at 5:15 AM Arnd Bergmann [off-list ref] wrote:

Thanks for the fix!

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

Sami

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 <redacted>

-- 
Kees Cook

+++ 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