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| author | Michael Niedermayer <michael@niedermayer.cc> | 2022-08-18 00:22:41 +0200 |
|---|---|---|
| committer | Michael Niedermayer <michael@niedermayer.cc> | 2022-09-01 00:41:28 +0200 |
| commit | 74f855fed2675384a17be497211445d7639e98ce (patch) | |
| tree | 98166b22858d02622db839e0674fa8fddc7a6295 | |
| parent | 408c0c43d7c201a586f76040f2ffcfb28a71d9f1 (diff) | |
| download | ffmpeg-74f855fed2675384a17be497211445d7639e98ce.tar.gz | |
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 <michael@niedermayer.cc>
(cherry picked from commit f3e823c2aa04d4f5571a5e04c27a244890704c8d)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
| -rw-r--r-- | libavformat/avidec.c | 12 |
1 files changed, 11 insertions, 1 deletions
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 */ |