Caught signal SIGSEGV when RTMP streaming server restart

Created by: nashiracn

Overview

I use PyAV to streaming video to RTMP server, when server restart, PyAV crashed with signal SIGSEGV.

Expected behavior

do not crash

Actual behavior

Traceback:

Investigation

file av/container/output.pyx method close_output() called twince. one is container.close(), another is container. __dealloc__ ()。

On first calling, self.err_check(lib.av_write_trailer(self.ptr)) rasie an Exception, so self._done not changed. but in libavformat av_write_trailer() freed AVFormatContext.priv_data。

On second calling， av_write_trailer() -> flv_write_trailer() will access AVFormatContext.priv_data which caught signal SIGSEGV

I mopdified av/container/output.pyx, I looks well:

diff --git a/av/container/output.pyx b/av/container/output.pyx
index 8781958..bdc756d 100644
--- a/av/container/output.pyx
+++ b/av/container/output.pyx
@@ -19,7 +19,10 @@ cdef close_output(OutputContainer self):
     cdef Stream stream

     if self._started and not self._done:
-        self.err_check(lib.av_write_trailer(self.ptr))
+        try:
+            self.err_check(lib.av_write_trailer(self.ptr))
+        except Exception as ex:
+            pass

         for stream in self.streams:
             stream.codec_context.close()

Reproduction

1. streaming to a RTMP server
2. restart RTMP server
3. container.close() twice

Versions

• OS: Debian 10.3
• PyAV runtime:

PyAV v7.0.2.dev0
git origin: git@github.com:mikeboers/PyAV
git commit: v6.2.0-132-gd9bebbd
library configuration: --disable-doc --disable-x86asm --enable-shared --disable-stripping
library license: LGPL version 2.1 or later
libavcodec     58. 76.100
libavdevice    58.  9.103
libavfilter     7. 77.100
libavformat    58. 42.100
libavutil      56. 42.101
libswresample   3.  6.100
libswscale      5.  6.101

• PyAV build:

running config
PyAV: 7.0.2.dev0 v6.2.0-132-gd9bebbd
Python: 3.7.3 (default, Dec 20 2019, 18:57:59) \n[GCC 8.3.0]
platform: Linux-4.19.0-8-amd64-x86_64-with-debian-10.3
extension_extra:
	include_dirs: [b'include', b'/usr/local/include']
	libraries: [b'avformat', b'avcodec', b'avdevice', b'avutil', b'avfilter', b'swscale', b'swresample']
	library_dirs: [b'/usr/local/lib']
	define_macros: []
	runtime_library_dirs: []
config_macros:
	PYAV_COMMIT_STR="v6.2.0-132-gd9bebbd"
	PYAV_VERSION=7.0.2.dev0
	PYAV_VERSION_STR="7.0.2.dev0"

• FFmpeg:

ffmpeg version N-97033-gc455a28a9e Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 8 (Debian 8.3.0-6)
configuration: --disable-doc --disable-x86asm --enable-shared --disable-stripping
libavutil      56. 42.101 / 56. 42.101
libavcodec     58. 76.100 / 58. 76.100
libavformat    58. 42.100 / 58. 42.100
libavdevice    58.  9.103 / 58.  9.103
libavfilter     7. 77.100 /  7. 77.100
libswscale      5.  6.101 /  5.  6.101
libswresample   3.  6.100 /  3.  6.100

Research

I have done the following:

• Checked the PyAV documentation
• Searched on Google
• Searched on Stack Overflow
• Looked through old GitHub issues

Additional context