diff mbox series

[v3,06/17] kthread: use WARN_ON_FUNCTION_MISMATCH

Message ID 20210323203946.2159693-7-samitolvanen@google.com (mailing list archive)
State New
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
__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 <samitolvanen@google.com>
---
 kernel/kthread.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Kees Cook March 26, 2021, 4:35 a.m. UTC | #1
On Tue, Mar 23, 2021 at 01:39:35PM -0700, Sami Tolvanen wrote:
> 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 <samitolvanen@google.com>

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

Patch

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