diff mbox series

[v3,05/17] workqueue: use WARN_ON_FUNCTION_MISMATCH

Message ID 20210323203946.2159693-6-samitolvanen@google.com (mailing list archive)
State New, archived
Headers show
Series Add support for Clang CFI | expand

Commit Message

Sami Tolvanen March 23, 2021, 8:39 p.m. UTC 
With CONFIG_CFI_CLANG, a callback function passed to
__queue_delayed_work from a module points to a jump table entry
defined in the module instead of the one used in the core kernel,
which breaks function address equality in this check:

  WARN_ON_ONCE(timer->function != delayed_work_timer_fn);

Use WARN_ON_FUNCTION_MISMATCH() instead to disable the warning
when CFI and modules are both enabled.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 kernel/workqueue.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Kees Cook March 26, 2021, 4:34 a.m. UTC | #1 
On Tue, Mar 23, 2021 at 01:39:34PM -0700, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, a callback function passed to
> __queue_delayed_work from a module points to a jump table entry
> defined in the module instead of the one used in the core kernel,
> which breaks function address equality in this check:
> 
>   WARN_ON_ONCE(timer->function != delayed_work_timer_fn);
> 
> Use WARN_ON_FUNCTION_MISMATCH() instead to disable the warning
> when CFI and modules are both enabled.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>
diff mbox series

Patch

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 0d150da252e8..03fe07d2f39f 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1630,7 +1630,7 @@  static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
 	struct work_struct *work = &dwork->work;
 
 	WARN_ON_ONCE(!wq);
-	WARN_ON_ONCE(timer->function != delayed_work_timer_fn);
+	WARN_ON_FUNCTION_MISMATCH(timer->function, delayed_work_timer_fn);
 	WARN_ON_ONCE(timer_pending(timer));
 	WARN_ON_ONCE(!list_empty(&work->entry));