Re: [PATCH] tracing: Fix crash passing ERR_PTR to kthread_stop()

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Silent Test Bypass
--

--- Patch [1]: [PATCH] tracing: Fix crash passing ERR_PTR to kthread_stop() ---
commit 40985725587eec80dcbbfbf251d18cd9797fe26c
Author: Hui Su <[email protected]>

    tracing: Fix crash passing ERR_PTR to kthread_stop()

    event_test_stuff() calls kthread_run() and unconditionally passes the
    returned task_struct pointer to kthread_stop(). kthread_run() returns an
    error pointer such as ERR_PTR(-ENOMEM) when kthread creation fails, for
    example under memory pressure during the boot-time event self-test.
    kthread_stop() then dereferences the invalid pointer, crashing the
    kernel.

> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index 0356cae0cf74e..207f47f54dbbf 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -3866,6 +3866,8 @@ static __init void event_test_stuff(void)
>  	struct task_struct *test_thread;
>  
>  	test_thread = kthread_run(event_test_thread, NULL, "test-events");
> +	if (IS_ERR(test_thread))
> +		return;

[Severity: Medium]
Does returning silently here cause the self-test framework to falsely report
success when the workload thread cannot be created?

The caller event_trace_self_tests() unconditionally prints "OK" after calling
this function:

kernel/trace/trace_events.c:event_trace_self_tests() {
        ...
		ftrace_event_enable_disable(file, 1);
		event_test_stuff();
		ftrace_event_enable_disable(file, 0);

		pr_cont("OK\n");
	}
        ...
}

Should event_test_stuff() propagate the error so that the caller can correctly
report the test failure or skip it appropriately?

>  	msleep(1);
>  	kthread_stop(test_thread);
>  }

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1