Re: [PATCH] um: Fix kcov crash before kernel is started.

[Richard Weinberger]

Am Sonntag, 8. Oktober 2017, 12:31:58 CEST schrieb Thomas Meyer:
> UMLs current_thread_info() unconditionally assumes that the top of the stack
> contains the thread_info structure. But on UML the __sanitizer_cov_trace_pc
> function is called for *all* functions! This results in an early crash:
> 
> Prevent kcov from using invalid curent_thread_info() data by checking
> the system_state.
> 
> Signed-off-by: Thomas Meyer <thomas@xxxxxxxx>
> ---
>  kernel/kcov.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/kernel/kcov.c b/kernel/kcov.c
> index 3f693a0f6f3e..d601c0e956f6 100644
> --- a/kernel/kcov.c
> +++ b/kernel/kcov.c
> @@ -56,6 +56,12 @@ void notrace __sanitizer_cov_trace_pc(void)
>  	struct task_struct *t;
>  	enum kcov_mode mode;
> 
> +#ifdef CONFIG_UML
> +	if(!(system_state == SYSTEM_SCHEDULING ||
> +	     system_state == SYSTEM_RUNNING))
> +		return;
> +#endif

Hmm, and why does it work on all other archs then?

Thanks,
//richard