[gstreamer-bugs] [Bug 514965] New: Possible buffer leaks if last_write_result != GST_FLOW_OK in gst_ebml_write_element_push

GStreamer (bugzilla.gnome.org) bugzilla-daemon at bugzilla.gnome.org
Thu Feb 7 04:51:59 PST 2008 

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  GStreamer | gst-plugins-good | Ver: HEAD CVS
           Summary: Possible buffer leaks if last_write_result !=
                    GST_FLOW_OK in gst_ebml_write_element_push
           Product: GStreamer
           Version: HEAD CVS
          Platform: Other
        OS/Version: All
            Status: UNCONFIRMED
          Severity: critical
          Priority: Normal
         Component: gst-plugins-good
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: bjarne at axis.com
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: Unspecified
   GNOME milestone: Unspecified


Please describe the problem:
(I'm new to gstreamer so I might have misunderstood some of this...) 
A GstBuffer will leak in gst_ebml_write_element_push () in ebml-write.c  if the
last gst_pad_push () call did not result in a GST_FLOW_OK. This is since the
GstBuffer is supposed to be unref'ed by gst_pad_push ().

A quick fix is the patch below but I'm not sure it is the best way of doing it
since it will only hide the problem...
diff -u -r1.1.1.2 ebml-write.c
--- gst-plugins-good/gst-plugins-good/gst/matroska/ebml-write.c  23 Aug 2006
16:11:26 -0000      1.1.1.2
+++ gst-plugins-good/gst-plugins-good/gst/matroska/ebml-write.c  7 Feb 2008
12:43:50 -0000
@@ -371,6 +371,8 @@
     buf = gst_buffer_make_metadata_writable (buf);
     gst_buffer_set_caps (buf, GST_PAD_CAPS (ebml->srcpad));
     ebml->last_write_result = gst_pad_push (ebml->srcpad, buf);
+  } else {
+    gst_buffer_unref (buf);
   }
 }


Steps to reproduce:
I found this after running a perhaps buggy pipeline that resulted in two eof
sent to the matroskamux. 
If I read the code correctly it might also be visible if a file error occurs
will gst_matroska_mux_finish is running, there is _no_ error checks in this
function at all...
I'm sorry to no have a more specific way of reproducing it.

Actual results:


Expected results:


Does this happen every time?


Other information:
Part of output from Valgrind:
==14820== 49,900 (39,920 direct, 9,980 indirect) bytes in 499 blocks are
definitely lost in loss record 3,793 of 3,794
==14820==    at 0x401D38B: malloc (vg_replace_malloc.c:149)
==14820==    by 0x43778E5: g_malloc (in
/home/bjarne/haiti/p1621_test/target/host/usr/lib/libglib-2.0.so.0.1400.5)
==14820==    by 0x438C722: g_slice_alloc (in
/home/bjarne/haiti/p1621_test/target/host/usr/lib/libglib-2.0.so.0.1400.5)
==14820==    by 0x438CE04: g_slice_alloc0 (in
/home/bjarne/haiti/p1621_test/target/host/usr/lib/libglib-2.0.so.0.1400.5)
==14820==    by 0x433224B: g_type_create_instance (in
/home/bjarne/haiti/p1621_test/target/host/usr/lib/libgobject-2.0.so.0.1400.5)
==14820==    by 0x419F9A5: gst_mini_object_new (gstminiobject.c:162)
==14820==    by 0x414DF35: gst_buffer_new (gstbuffer.c:291)
==14820==    by 0x414E030: gst_buffer_new_and_alloc (gstbuffer.c:320)
==14820==    by 0x68F2332: gst_ebml_write_element_new (ebml-write.c:234)
==14820==    by 0x68F2BC4: gst_ebml_write_uint (ebml-write.c:475)
==14820==    by 0x6904A7A: gst_matroska_mux_finish (matroska-mux.c:1535)
==14820==    by 0x69065A2: gst_matroska_mux_collected (matroska-mux.c:1938)
==14820==    by 0x4063090: gst_collect_pads_check_collected
(gstcollectpads.c:954)
==14820==    by 0x4063AC3: gst_collect_pads_event (gstcollectpads.c:1054)
==14820==    by 0x6901084: gst_matroska_mux_handle_sink_event
(matroska-mux.c:497)
==14820==    by 0x41BCA33: gst_pad_send_event (gstpad.c:4256)
==14820==    by 0x41BB9E6: gst_pad_push_event (gstpad.c:4112)
==14820==    by 0x4058601: gst_base_transform_sink_event
(gstbasetransform.c:1236)
==14820==    by 0x41BCA33: gst_pad_send_event (gstpad.c:4256)
==14820==    by 0x41BB9E6: gst_pad_push_event (gstpad.c:4112)
==14820==    by 0x418681A: gst_proxy_pad_do_event (gstghostpad.c:140)
==14820==    by 0x41BCA33: gst_pad_send_event (gstpad.c:4256)
==14820==    by 0x41BB9E6: gst_pad_push_event (gstpad.c:4112)
==14820==    by 0x404E1F8: gst_base_src_loop (gstbasesrc.c:2091)
==14820==    by 0x41F86B6: gst_task_func (gsttask.c:192)
==14820==    by 0x43952D6: (within
/home/bjarne/haiti/p1621_test/target/host/usr/lib/libglib-2.0.so.0.1400.5)
==14820==    by 0x439374E: (within
/home/bjarne/haiti/p1621_test/target/host/usr/lib/libglib-2.0.so.0.1400.5)
==14820==    by 0x440423F: start_thread (in
/lib/tls/i686/cmov/libpthread-2.3.6.so)
==14820==    by 0x44DC4AD: clone (in /lib/tls/i686/cmov/libc-2.3.6.so)


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