[Bug 723615] New: SIGSEGV when setting preload option in gst_ffmpegmux_setcaps

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=723615
  GStreamer | gst-libav | git

           Summary: SIGSEGV when setting preload option in
                    gst_ffmpegmux_setcaps
    Classification: Platform
           Product: GStreamer
           Version: git
        OS/Version: All
            Status: UNCONFIRMED
          Severity: blocker
          Priority: Normal
         Component: gst-libav
        AssignedTo: gstreamer-bugs at lists.freedesktop.org
        ReportedBy: dmitry.m at samsung.com
         QAContact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---


Trying to encode video using libav through gst-libav I faced following problem:

#0  strcmp (p1=0x10040 <Address 0x10040 out of bounds>, 
    p2=0xb61ee768 "preload") at strcmp.c:38
#1  0xb61e383c in av_opt_find2 (obj=0x1d10c0, name=0xb61ee768 "preload", 
    unit=0x0, opt_flags=0, search_flags=0, target_obj=0xb33fea4c)
    at libavutil/opt.c:663
#2  0xb61e4016 in set_number (obj=0x1d10c0, name=<value optimized out>, 
    val=<value optimized out>, search_flags=0) at libavutil/opt.c:253
#3  av_opt_set_int (obj=0x1d10c0, name=<value optimized out>, 
    val=<value optimized out>, search_flags=0) at libavutil/opt.c:264
#4  0xb5e5a796 in gst_ffmpegmux_setcaps (pad=0x1d4e78, parent=0x1d1000, 
    event=0x8d4888) at gstavmux.c:477
#5  gst_ffmpegmux_sink_event (pad=0x1d4e78, parent=0x1d1000, event=0x8d4888)
    at gstavmux.c:520
#6  0xb6be381c in gst_pad_send_event_unchecked (pad=0x1d4e78, event=0x8d4888, 
    type=<value optimized out>) at gstpad.c:4986


Problem is: code tryes to access field name on object o of type AVOption when o
is invalid.
After investigation I found that problem is cast of method param obj to type
AVClass:
const AVClass  *c = *(AVClass**)obj;

AVFormatContext struct contains field av_class of type AVClass* which is 1st
field, so change of code from:
    av_opt_set_int(&ffmpegmux->context, "preload", ffmpegmux->preload, 0);
to
    av_opt_set_int(&ffmpegmux->context->av_class, "preload",
ffmpegmux->preload, 0); // more readable
or
    av_opt_set_int(ffmpegmux->context, "preload", ffmpegmux->preload, 0); //
corrects address passing
fixes my problem.

-- 
Configure bugmail: https://bugzilla.gnome.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
You are the assignee for the bug.