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

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

[Daniel Bristot de Oliveira]

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

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

[John Kacur]

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

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

[Steven Rostedt]

On Wed, 18 Nov 2015 00:57:14 +0100 (CET)
John Kacur <jkacur@redhat.com> wrote:

> 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>
  
> Tested-by: John Kacur <jkacur@redhat.com>
> 
> Works well, please apply

Applied. Thanks!

-- Steve