[Bug 775120] New: mpegts parser: null pointer deref in _parse_pat

[GStreamer (GNOME Bugzilla)]

https://bugzilla.gnome.org/show_bug.cgi?id=775120

            Bug ID: 775120
           Summary: mpegts parser: null pointer deref in _parse_pat
    Classification: Platform
           Product: GStreamer
           Version: git master
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: Normal
         Component: gst-plugins-bad
          Assignee: gstreamer-bugs at lists.freedesktop.org
          Reporter: hanno at hboeck.de
        QA Contact: gstreamer-bugs at lists.freedesktop.org
     GNOME version: ---

Created attachment 340777
  --> https://bugzilla.gnome.org/attachment.cgi?id=340777&action=edit
poc file

The attached file will cause a null pointer access and segfault in the mpegts
parser. Current git code, found with afl.

ASAN stack trace:
=================================================================
==32545==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000000 (pc
0x7fe957185495 bp 0x60200002cf7a sp 0x7fe956e027a0 T2)
==32545==The signal is caused by a WRITE memory access.
==32545==Hint: address points to the zero page.
    #0 0x7fe957185494 in _parse_pat
/f/gstreamer/gst-plugins-bad/gst-libs/gst/mpegts/gstmpegtssection.c:441:32
    #1 0x7fe957184058 in __common_section_checks
/f/gstreamer/gst-plugins-bad/gst-libs/gst/mpegts/gstmpegtssection.c:166:9
    #2 0x7fe95718522f in gst_mpegts_section_get_pat
/f/gstreamer/gst-plugins-bad/gst-libs/gst/mpegts/gstmpegtssection.c:480:9
    #3 0x7fe957438b9a in mpegts_base_apply_pat
/f/gstreamer/gst-plugins-bad/gst/mpegtsdemux/mpegtsbase.c:942:20
    #4 0x7fe957438b9a in mpegts_base_handle_psi
/f/gstreamer/gst-plugins-bad/gst/mpegtsdemux/mpegtsbase.c:1155
    #5 0x7fe957437cd1 in mpegts_base_chain
/f/gstreamer/gst-plugins-bad/gst/mpegtsdemux/mpegtsbase.c:1424:11
    #6 0x7fe9574341e7 in mpegts_base_loop
/f/gstreamer/gst-plugins-bad/gst/mpegtsdemux/mpegtsbase.c:1589:13
    #7 0x7fe9644305c3 in gst_task_func
/f/gstreamer/gstreamer/gst/gsttask.c:334:5
    #8 0x7fe96362f867  (/usr/lib64/libglib-2.0.so.0+0x70867)
    #9 0x7fe96362eed4  (/usr/lib64/libglib-2.0.so.0+0x6fed4)
    #10 0x7fe9630ac443 in start_thread (/lib64/libpthread.so.0+0x7443)
    #11 0x7fe962bdb92c in clone (/lib64/libc.so.6+0xe792c)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV
/f/gstreamer/gst-plugins-bad/gst-libs/gst/mpegts/gstmpegtssection.c:441:32 in
_parse_pat
Thread T2 (tsdemux0:sink) created by T1 (typefind:sink) here:
    #0 0x42e26d in __interceptor_pthread_create
(/usr/bin/gst-discoverer-1.0+0x42e26d)
    #1 0x7fe96364cadf  (/usr/lib64/libglib-2.0.so.0+0x8dadf)

Thread T1 (typefind:sink) created by T0 here:
    #0 0x42e26d in __interceptor_pthread_create
(/usr/bin/gst-discoverer-1.0+0x42e26d)
    #1 0x7fe96364cadf  (/usr/lib64/libglib-2.0.so.0+0x8dadf)

==32545==ABORTING

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