On 4/7/2020 10:57 AM, Anton Khirnov wrote: > Quoting James Almer (2020-03-27 16:08:11) >> On 3/27/2020 9:57 AM, Anton Khirnov wrote: >>> This tells the parsing functions the payload size and prevents them from >>> overreading. >>> --- >>> libavcodec/h264_sei.c | 33 +++++++++++++++++++-------------- >>> 1 file changed, 19 insertions(+), 14 deletions(-) >>> >>> diff --git a/libavcodec/h264_sei.c b/libavcodec/h264_sei.c >>> index a565feabe2..32d13985f3 100644 >>> --- a/libavcodec/h264_sei.c >>> +++ b/libavcodec/h264_sei.c >>> @@ -407,9 +407,9 @@ int ff_h264_sei_decode(H264SEIContext *h, GetBitContext >>> *gb, >>> int master_ret = 0; >>> >>> while (get_bits_left(gb) > 16 && show_bits(gb, 16)) { >>> + GetBitContext gb_payload; >>> int type = 0; >>> unsigned size = 0; >>> - unsigned next; >>> int ret = 0; >>> >>> do { >>> @@ -429,35 +429,38 @@ int ff_h264_sei_decode(H264SEIContext *h, >>> GetBitContext *gb, >>> type, 8*size, get_bits_left(gb)); >>> return AVERROR_INVALIDDATA; >>> } >>> - next = get_bits_count(gb) + 8 * size; >>> + >>> + ret = init_get_bits8(&gb_payload, gb->buffer + get_bits_count(gb) >>> / 8, size); >> >> Could use init_get_bits() instead, since size was already checked above. > > ok, done locally > >> >>> + if (ret < 0) >>> + return ret; >>> >>> switch (type) { >>> case H264_SEI_TYPE_PIC_TIMING: // Picture timing SEI >>> - ret = decode_picture_timing(&h->picture_timing, gb, ps, >>> logctx); >>> + ret = decode_picture_timing(&h->picture_timing, &gb_payload, >>> ps, logctx); >>> break; >>> case H264_SEI_TYPE_USER_DATA_REGISTERED: >>> - ret = decode_registered_user_data(h, gb, logctx, size); >>> + ret = decode_registered_user_data(h, &gb_payload, logctx, >>> size); >>> break; >>> case H264_SEI_TYPE_USER_DATA_UNREGISTERED: >>> - ret = decode_unregistered_user_data(&h->unregistered, gb, >>> logctx, size); >>> + ret = decode_unregistered_user_data(&h->unregistered, >>> &gb_payload, logctx, size); >>> break; >>> case H264_SEI_TYPE_RECOVERY_POINT: >>> - ret = decode_recovery_point(&h->recovery_point, gb, logctx); >>> + ret = decode_recovery_point(&h->recovery_point, &gb_payload, >>> logctx); >>> break; >>> case H264_SEI_TYPE_BUFFERING_PERIOD: >>> - ret = decode_buffering_period(&h->buffering_period, gb, ps, >>> logctx); >>> + ret = decode_buffering_period(&h->buffering_period, >>> &gb_payload, ps, logctx); >>> break; >>> case H264_SEI_TYPE_FRAME_PACKING: >>> - ret = decode_frame_packing_arrangement(&h->frame_packing, gb); >>> + ret = decode_frame_packing_arrangement(&h->frame_packing, >>> &gb_payload); >>> break; >>> case H264_SEI_TYPE_DISPLAY_ORIENTATION: >>> - ret = decode_display_orientation(&h->display_orientation, gb); >>> + ret = decode_display_orientation(&h->display_orientation, >>> &gb_payload); >>> break; >>> case H264_SEI_TYPE_GREEN_METADATA: >>> - ret = decode_green_metadata(&h->green_metadata, gb); >>> + ret = decode_green_metadata(&h->green_metadata, &gb_payload); >>> break; >>> case H264_SEI_TYPE_ALTERNATIVE_TRANSFER: >>> - ret = decode_alternative_transfer(&h->alternative_transfer, >>> gb); >>> + ret = decode_alternative_transfer(&h->alternative_transfer, >>> &gb_payload); >>> break; >>> default: >>> av_log(logctx, AV_LOG_DEBUG, "unknown SEI type %d\n", type); >>> @@ -467,10 +470,12 @@ int ff_h264_sei_decode(H264SEIContext *h, >>> GetBitContext *gb, >>> if (ret < 0) >>> master_ret = ret; >>> >>> - skip_bits_long(gb, next - get_bits_count(gb)); >>> + if (get_bits_left(&gb_payload) < 0) { >>> + av_log(logctx, AV_LOG_WARNING, "SEI type %d overread by %d >>> bits\n", >>> + type, -get_bits_left(&gb_payload)); >> >> Maybe check for explode and abort? > > We don't have access to explode, so it'd have to be passed in > explicitly. That seemed like too much effort to be worth it.
Ah, true. LGTM then. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".