[FFmpeg-devel] [PATCH] avcodec/h2645_parse: remove initial skipped_bytes_pos buffer
Andreas Rheinhardt
andreas.rheinhardt at gmail.com
Sat Oct 10 01:43:53 EEST 2020
James Almer:
> Allocate it only when it's needed.
>
> Fixes: OOM
> Fixes: 23817/clusterfuzz-testcase-minimized-ffmpeg_BSF_H264_METADATA_fuzzer-6300869057576960
>
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> libavcodec/h2645_parse.c | 28 ++++++++++------------------
> 1 file changed, 10 insertions(+), 18 deletions(-)
>
> diff --git a/libavcodec/h2645_parse.c b/libavcodec/h2645_parse.c
> index 0f98b49fbe..929fb34eef 100644
> --- a/libavcodec/h2645_parse.c
> +++ b/libavcodec/h2645_parse.c
> @@ -108,22 +108,20 @@ int ff_h2645_extract_rbsp(const uint8_t *src, int length,
> dst[di++] = 0;
> si += 3;
>
> - if (nal->skipped_bytes_pos) {
> - nal->skipped_bytes++;
> - if (nal->skipped_bytes_pos_size < nal->skipped_bytes) {
> - nal->skipped_bytes_pos_size *= 2;
> - av_assert0(nal->skipped_bytes_pos_size >= nal->skipped_bytes);
> - av_reallocp_array(&nal->skipped_bytes_pos,
> + nal->skipped_bytes++;
> + if (nal->skipped_bytes_pos_size < nal->skipped_bytes) {
> + nal->skipped_bytes_pos_size = nal->skipped_bytes * 2;
> + av_assert0(nal->skipped_bytes_pos_size >= nal->skipped_bytes);
> + av_reallocp_array(&nal->skipped_bytes_pos,
> nal->skipped_bytes_pos_size,
> sizeof(*nal->skipped_bytes_pos));
> - if (!nal->skipped_bytes_pos) {
> - nal->skipped_bytes_pos_size = 0;
> - return AVERROR(ENOMEM);
> - }
> + if (!nal->skipped_bytes_pos) {
> + nal->skipped_bytes_pos_size = 0;
> + return AVERROR(ENOMEM);
> }
> - if (nal->skipped_bytes_pos)
> - nal->skipped_bytes_pos[nal->skipped_bytes-1] = di - 1;
> }
> + if (nal->skipped_bytes_pos)
> + nal->skipped_bytes_pos[nal->skipped_bytes-1] = di - 1;
> continue;
> } else // next start code
> goto nsc;
> @@ -466,12 +464,6 @@ int ff_h2645_packet_split(H2645Packet *pkt, const uint8_t *buf, int length,
> pkt->nals = tmp;
> memset(pkt->nals + pkt->nals_allocated, 0, sizeof(*pkt->nals));
>
> - nal = &pkt->nals[pkt->nb_nals];
> - nal->skipped_bytes_pos_size = 1024; // initial buffer size
> - nal->skipped_bytes_pos = av_malloc_array(nal->skipped_bytes_pos_size, sizeof(*nal->skipped_bytes_pos));
> - if (!nal->skipped_bytes_pos)
> - return AVERROR(ENOMEM);
> -
> pkt->nals_allocated = new_size;
> }
> nal = &pkt->nals[pkt->nb_nals];
>
This has the disadvantage that it always keeps the position of the 0x03
even when the caller does not want it; most callers don't want it, the
only exception is the HEVC decoder. Your patch will lead to memleaks for
the users that use ff_h2645_extract_rbsp() directly.
- Andreas
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