Re: [PATCH 2/3] tracing: Adding additional NULL checks.

[Steven Rostedt]

On Wed, 12 Jun 2019 09:34:18 -0700
Divya Indi <divya.indi@xxxxxxxxxx> wrote:

> commit f45d1225adb0 ("tracing: Kernel access to Ftrace instances")
> exported certain functions providing access to Ftrace instances from
> other kernel components.

I'm fine with the patch, the above statement is hard to understand.

-- Steve

> Adding some additional NULL checks to ensure safe usage by the users.
> 
> Signed-off-by: Divya Indi <divya.indi@xxxxxxxxxx>
> ---
>  kernel/trace/trace.c        | 3 +++
>  kernel/trace/trace_events.c | 2 ++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 1c80521..a60dc13 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -3205,6 +3205,9 @@ int trace_array_printk(struct trace_array *tr,
>  	if (!(global_trace.trace_flags & TRACE_ITER_PRINTK))
>  		return 0;
>  
> +	if (!tr)
> +		return -EINVAL;
> +
>  	va_start(ap, fmt);
>  	ret = trace_array_vprintk(tr, ip, fmt, ap);
>  	va_end(ap);
> diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> index b6b4618..445b059 100644
> --- a/kernel/trace/trace_events.c
> +++ b/kernel/trace/trace_events.c
> @@ -800,6 +800,8 @@ int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set)
>  	char *event = NULL, *sub = NULL, *match;
>  	int ret;
>  
> +	if (!tr)
> +		return -ENODEV;
>  	/*
>  	 * The buf format can be <subsystem>:<event-name>
>  	 *  *:<event-name> means any event by that name.