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Code Issues Releases Activity

avformat/cinedec: Avoid repeatedly allocating packets beyond the input

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Fixes: Timeout
Fixes: 41025/clusterfuzz-testcase-minimized-ffmpeg_dem_CINE_fuzzer-5540848285122560

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2021-11-27 20:48:27 +01:00
parent 8e96410e1b
commit e22ec484aa
1 changed files with 13 additions and 1 deletions
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14
libavformat/cinedec.c
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@ -33,6 +33,7 @@
typedef struct { typedef struct {
uint64_t pts; uint64_t pts;
uint64_t maxsize;
} CineDemuxContext; } CineDemuxContext;
/** Compression */ /** Compression */
@ -288,21 +289,32 @@ static int cine_read_packet(AVFormatContext *avctx, AVPacket *pkt)
FFStream *const sti = ffstream(st); FFStream *const sti = ffstream(st);
AVIOContext *pb = avctx->pb; AVIOContext *pb = avctx->pb;
int n, size, ret; int n, size, ret;
int64_t ret64;
if (cine->pts >= sti->nb_index_entries) if (cine->pts >= sti->nb_index_entries)
return AVERROR_EOF; return AVERROR_EOF;
avio_seek(pb, sti->index_entries[cine->pts].pos, SEEK_SET); ret64 = avio_seek(pb, sti->index_entries[cine->pts].pos, SEEK_SET);
if (ret64 < 0)
return ret64;
n = avio_rl32(pb); n = avio_rl32(pb);
if (n < 8) if (n < 8)
return AVERROR_INVALIDDATA; return AVERROR_INVALIDDATA;
avio_skip(pb, n - 8); avio_skip(pb, n - 8);
size = avio_rl32(pb); size = avio_rl32(pb);
if (avio_feof(pb))
return AVERROR_INVALIDDATA;
if (cine->maxsize && sti->index_entries[cine->pts].pos + size + n > cine->maxsize)
size = cine->maxsize - sti->index_entries[cine->pts].pos - n;
ret = av_get_packet(pb, pkt, size); ret = av_get_packet(pb, pkt, size);
if (ret < 0) if (ret < 0)
return ret; return ret;
if (ret != size)
cine->maxsize = sti->index_entries[cine->pts].pos + n + ret;
pkt->pts = cine->pts++; pkt->pts = cine->pts++;
pkt->stream_index = 0; pkt->stream_index = 0;
pkt->flags |= AV_PKT_FLAG_KEY; pkt->flags |= AV_PKT_FLAG_KEY;