Created attachment 306140 [details] [review]
It is a prevent defect which dereference null return value. 'gst_flups_demux_get_stream' function could return NULL when it is unknown stream. So I added NULL check.

Created attachment 306141 [details] [review]
I fixed a typing error in patch.

Created attachment 306142 [details] [review]
Sorry, I attached the patch again.

Fix a prevent defect which dereference null return value.
'gst_ps_demux_get_stream' function could return NULL when it is unknown stream.
So I added NULL check.

Comment on attachment 306142 [details] [review]
Sorry, I attached the patch again.

>From 261d6534f23958d22de025a29b5d3aa7b906ac45 Mon Sep 17 00:00:00 2001
>From: Sangkyu Park <sk1122.park@samsung.com>
>Date: Fri, 26 Jun 2015 15:58:25 +0900
>Subject: [PATCH] mpegdemux: Minor clean-up
>
>Fix a prevent defect which dereference null return value.
>'gst_ups_demux_get_stream' function could return NULL when it is unknown stream.
>
>https://bugzilla.gnome.org/show_bug.cgi?id=751528
>---
> gst/mpegdemux/gstmpegdemux.c |    4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
> mode change 100644 => 100755 gst/mpegdemux/gstmpegdemux.c
>
>diff --git a/gst/mpegdemux/gstmpegdemux.c b/gst/mpegdemux/gstmpegdemux.c
>old mode 100644
>new mode 100755
>index ab9b364..54551c9
>--- a/gst/mpegdemux/gstmpegdemux.c
>+++ b/gst/mpegdemux/gstmpegdemux.c
>@@ -824,7 +824,7 @@ gst_ps_demux_handle_dvd_event (GstPsDemux * demux, GstEvent * event)
> 
>       g_snprintf (cur_stream_name, 32, "audio-%d-language", i);
>       lang_code = gst_structure_get_string (structure, cur_stream_name);
>-      if (lang_code) {
>+      if (lang_code && temp) {
>         GstTagList *list = temp->pending_tags;
> 
>         if (!list)
>@@ -855,6 +855,8 @@ gst_ps_demux_handle_dvd_event (GstPsDemux * demux, GstEvent * event)
>       /* Retrieve the subpicture stream to force pad creation */
>       temp = gst_ps_demux_get_stream (demux, 0x20 + stream_id,
>           ST_PS_DVD_SUBPICTURE);
>+      if (temp == NULL)
>+        continue;
> 
>       g_snprintf (cur_stream_name, 32, "subpicture-%d-language", i);
>       lang_code = gst_structure_get_string (structure, cur_stream_name);
>-- 
>1.7.9.5
>

Hi 
you can mark the previous patches as obsolete, so that there will be no duplications

Created attachment 306143 [details] [review]
Sorry, it has a typing error in patch so I updated it again.

Created attachment 306144 [details] [review]
I updated, Thanks :)

It is a prevent defect which dereference null return value. 'gst_ps_demux_get_stream' function could return NULL when it is unknown stream. So I added NULL check.

Review of attachment 306144 [details] [review]:

::: gst/mpegdemux/gstmpegdemux.c
@@ +825,3 @@
       g_snprintf (cur_stream_name, 32, "audio-%d-language", i);
       lang_code = gst_structure_get_string (structure, cur_stream_name);
+      if (lang_code && temp) {

it might be better to break for default case and add
if (temp == NULL)
  continue;
before line 825

Created attachment 306146 [details] [review]
I updated it

Created attachment 306147 [details] [review]
Sorry I updated it again. I know that must recopy commit tag also when making patch again.

I'm beginner about contributing open source. sorry I have made many mistakes.

Two things.

 - Don't compare to NULL, when you can directly do if (!temp).
 - In GStreamer's coding style we add a space between the 'if' and the '('.

Logic of patch is good. The code must check if gst_ps_demux_get_stream () returned NULL before dereferencing temp.

Change it to:

if (!temp)
  continue;

Sangkyu,

Tim pointed out that the norm is to compare to NULL to make it clear a pointer is being checked and not a boolean. I went ahead and fixed your space between if and '(' and submitted.

Thank you for your contribution :)

Review of attachment 306147 [details] [review]:

commit 0ca354eb102d883d0bc4cb9762c8911ccf698ffc
Author: Sangkyu Park <sk1122.park@samsung.com>
Date:   Fri Jun 26 15:58:25 2015 +0900

    mpegdemux: check pointer before dereferencing

    gst_ps_demux_get_stream() could return NULL when it is unknown stream,
    check this hasn't happened before dereferencing the returned pointer.

    https://bugzilla.gnome.org/show_bug.cgi?id=751528

(clean-up is something that doesn't change behaviour :))

Vineeth, Luis and Tim-philipp, Thanks for your advice :)
I will check one more next time for no mistake.