ffmpeg | branch: release/5.0 | Michael Niedermayer <mich...@niedermayer.cc> | Thu Aug 18 00:22:41 2022 +0200| [74f855fed2675384a17be497211445d7639e98ce] | committer: Michael Niedermayer
avformat/avidec: Prevent entity expansion attacks Fixes: Timeout Fixes no testcase, this is the same idea as similar attacks against XML parsers Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> (cherry picked from commit f3e823c2aa04d4f5571a5e04c27a244890704c8d) Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=74f855fed2675384a17be497211445d7639e98ce --- libavformat/avidec.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/libavformat/avidec.c b/libavformat/avidec.c index 8584b4a882..c1f3294637 100644 --- a/libavformat/avidec.c +++ b/libavformat/avidec.c @@ -79,6 +79,8 @@ typedef struct AVIContext { int stream_index; DVDemuxContext *dv_demux; int odml_depth; + int64_t odml_read; + int64_t odml_max_pos; int use_odml; #define MAX_ODML_DEPTH 1000 int64_t dts_max; @@ -197,7 +199,7 @@ static int read_odml_index(AVFormatContext *s, int64_t frame_num) st = s->streams[stream_id]; ast = st->priv_data; - if (index_sub_type) + if (index_sub_type || entries_in_use < 0) return AVERROR_INVALIDDATA; avio_rl32(pb); @@ -218,11 +220,18 @@ static int read_odml_index(AVFormatContext *s, int64_t frame_num) } for (i = 0; i < entries_in_use; i++) { + avi->odml_max_pos = FFMAX(avi->odml_max_pos, avio_tell(pb)); + + // If we read more than there are bytes then we must have been reading something twice + if (avi->odml_read > avi->odml_max_pos) + return AVERROR_INVALIDDATA; + if (index_type) { int64_t pos = avio_rl32(pb) + base - 8; int len = avio_rl32(pb); int key = len >= 0; len &= 0x7FFFFFFF; + avi->odml_read += 8; av_log(s, AV_LOG_TRACE, "pos:%"PRId64", len:%X\n", pos, len); @@ -241,6 +250,7 @@ static int read_odml_index(AVFormatContext *s, int64_t frame_num) int64_t offset, pos; int duration; int ret; + avi->odml_read += 16; offset = avio_rl64(pb); avio_rl32(pb); /* size */ _______________________________________________ ffmpeg-cvslog mailing list ffmpeg-cvslog@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog To unsubscribe, visit link above, or email ffmpeg-cvslog-requ...@ffmpeg.org with subject "unsubscribe".
