With CONFIG_CFI_CLANG, a callback function passed to
__kthread_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 != ktead_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 <samitolva...@google.com>
Reviewed-by: Kees Cook <keesc...@chromium.org>
Tested-by: Nathan Chancellor <nat...@kernel.org>
---
 kernel/kthread.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 1578973c5740..a1972eba2917 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -963,7 +963,8 @@ static void __kthread_queue_delayed_work(struct 
kthread_worker *worker,
        struct timer_list *timer = &dwork->timer;
        struct kthread_work *work = &dwork->work;
 
-       WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn);
+       WARN_ON_FUNCTION_MISMATCH(timer->function,
+                                 kthread_delayed_work_timer_fn);
 
        /*
         * If @delay is 0, queue @dwork->work immediately.  This is for
-- 
2.31.1.295.g9ea45b61b8-goog

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