0685bd0245
The MPEG-PS muxer uses a custom queue of custom packets. To keep track of it, it has a pointer (named predecode_packet) to the head of the queue and a pointer to where the next packet is to be added (it points to the next-pointer of the last element of the queue); furthermore, there is also a pointer that points into the queue (called premux_packet). The exact behaviour was as follows: If premux_packet was NULL when a packet is received, it is taken to mean that the old queue is empty and a new queue is started. premux_packet will point to the head of said queue and the next_packet-pointer points to its next pointer. If predecode_packet is NULL, it will also made to point to the newly allocated element. But if premux_packet is NULL and predecode_packet is not, then there will be two queues with head elements premux_packet and predecode_packet. Yet only elements reachable from predecode_packet are ever freed, so the premux_packet queue leaks. Worse yet, when the predecode_packet queue will be eventually exhausted, predecode_packet will be made to point into the other queue and when predecode_packet will be freed, the next pointer of the preceding element of the queue will still point to the element just freed. This element might very well be still reachable from premux_packet which leads to use-after-frees lateron. This happened in the tickets mentioned below. Fix this by never creating two queues in the first place by checking for predecode_packet to know whether the queue is empty. If premux_packet is NULL, then it is set to the newly allocated element of the queue. Fixes tickets #6887, #8188 and #8266. Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com> (cherry picked from commit cfce16449cb815132f829d5a07beb138dfb2cba6)
FFmpeg README
FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.
Libraries
libavcodecprovides implementation of a wider range of codecs.libavformatimplements streaming protocols, container formats and basic I/O access.libavutilincludes hashers, decompressors and miscellaneous utility functions.libavfilterprovides a mean to alter decoded Audio and Video through chain of filters.libavdeviceprovides an abstraction to access capture and playback devices.libswresampleimplements audio mixing and resampling routines.libswscaleimplements color conversion and scaling routines.
Tools
- ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
- ffplay is a minimalistic multimedia player.
- ffprobe is a simple analysis tool to inspect multimedia content.
- Additional small tools such as
aviocat,ismindexandqt-faststart.
Documentation
The offline documentation is available in the doc/ directory.
The online documentation is available in the main website and in the wiki.
Examples
Coding examples are available in the doc/examples directory.
License
FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.
Contributing
Patches should be submitted to the ffmpeg-devel mailing list using
git format-patch or git send-email. Github pull requests should be
avoided because they are not part of our review process and will be ignored.