I have a Matroska file that contains a broken chapter (end time is before
start time) that caused any ffmpeg-linked program to crash when accessing
it. I've attached a patch that fixes the crash. Also, here is the backtrace
of the crash for reference:
(gdb) backtrace
#0 av_dict_set (pm=0x20, key=0x7ffff0bd14ef "title", value=0x7fffd80107e0
"The End", flags=0) at libavutil/dict.c:71
#1 0x00007ffff0b0e220 in matroska_read_header (s=0x20) at
libavformat/matroskadec.c:2164
#2 0x00007ffff0b9b233 in avformat_open_input (ps=0x7fffe00c1a08,
filename=<optimized out>, fmt=<optimized out>, options=0x0) at
libavformat/utils.c:599
#3 0x00007ffff5fc9c32 in
ffmpegthumbnailer::MovieDecoder::initialize(std::string const&) () from
/usr/lib/libffmpegthumbnailer.so.4
#4 0x00007ffff5fcd50f in
ffmpegthumbnailer::VideoThumbnailer::generateThumbnail(std::string const&,
ffmpegthumbnailer::ImageWriter&, AVFormatContext*) ()
from /usr/lib/libffmpegthumbnailer.so.4
#5 0x00007ffff5fcd911 in
ffmpegthumbnailer::VideoThumbnailer::generateThumbnail(std::string const&,
ThumbnailerImageTypeEnum, std::string const&, AVFormatContext*) ()
from /usr/lib/libffmpegthumbnailer.so.4
#6 0x00007ffff5fce636 in video_thumbnailer_generate_thumbnail_to_file ()
from /usr/lib/libffmpegthumbnailer.so.4
#7 0x00000000004314e5 in ?? ()
#8 0x00000000004319a0 in ?? ()
#9 0x000000000042221f in ?? ()
#10 0x00000000004310bb in ?? ()
#11 0x0000000000430dd0 in ?? ()
#12 0x00007ffff644ec95 in ?? () from /usr/lib/libglib-2.0.so.0
#13 0x00007ffff5766124 in start_thread () from /usr/lib/libpthread.so.0
#14 0x00007ffff549a4bd in clone () from /usr/lib/libc.so.6
Thanks,
Justin
From 14c4bcd96e6677c93b730faf0b4bf296e12bfd79 Mon Sep 17 00:00:00 2001
From: Justin Jacobs <jajdorks...@gmail.com>
Date: Wed, 6 Aug 2014 20:04:38 -0400
Subject: [PATCH] NULL-check Matroska chapters when reading header
---
libavformat/matroskadec.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 50b75e7..10969de 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -2161,8 +2161,10 @@ static int matroska_read_header(AVFormatContext *s)
(AVRational) { 1, 1000000000 },
chapters[i].start, chapters[i].end,
chapters[i].title);
- av_dict_set(&chapters[i].chapter->metadata,
- "title", chapters[i].title, 0);
+ if (chapters[i].chapter) {
+ av_dict_set(&chapters[i].chapter->metadata,
+ "title", chapters[i].title, 0);
+ }
max_start = chapters[i].start;
}
--
2.0.4
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