Re: [PATCH] trace-cmd: record crashes if -f is used before -e event.

[John Kacur <jkacur@redhat.com>]

On Mon, 20 Jul 2015, Daniel Bristot de Oliveira wrote:

> The trace-cmd record command is crashing if a -f filter is used before
> a -e event.
> 
> The usage a -f before a -e is a command line error, and trace-cmd
> record detects this error by checking if the last_event pointer is NULL.
> 
> However, the last_event is not initialized as NULL and this command line
> error is not detected. Then, the last_event is used to save the filter
> options and this causes a segmentation fault because last_event was not
> initialized yet.
> 
> This problem is fixed by initializing last_event as NULL.
> 
> How-to reproduce:
>   # trace-cmd record -f foo
>   Segmentation fault
> 
> Expected output:
>   # trace-cmd record -f foo
>   filter must come after event
> 
> Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
> ---
>  trace-record.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/trace-record.c b/trace-record.c
> index 3e5def2..45826b6 100644
> --- a/trace-record.c
> +++ b/trace-record.c
> @@ -2686,7 +2686,7 @@ void trace_record (int argc, char **argv)
>  	const char *output = NULL;
>  	const char *option;
>  	struct event_list *event;
> -	struct event_list *last_event;
> +	struct event_list *last_event = NULL;
>  	struct tracecmd_event_list *list;
>  	struct buffer_instance *instance = &top_instance;
>  	enum trace_type type;
> -- 
> 2.1.0
> 
Tested-by: John Kacur <jkacur@redhat.com>

Works well, please apply