[FFmpeg-devel] [PATCH 08/25] avcodec/magicyuv: Replace implicit checks for overread by explicit ones
Andreas Rheinhardt
andreas.rheinhardt at gmail.com
Sat Sep 26 13:43:17 EEST 2020
Paul B Mahol:
> On Sat, Sep 26, 2020 at 12:27:47PM +0200, Andreas Rheinhardt wrote:
>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>> ---
>> libavcodec/magicyuv.c | 49 ++++++++++++++++++++++++-------------------
>> 1 file changed, 27 insertions(+), 22 deletions(-)
>>
>> diff --git a/libavcodec/magicyuv.c b/libavcodec/magicyuv.c
>> index 3413d8f298..93ee739093 100644
>> --- a/libavcodec/magicyuv.c
>> +++ b/libavcodec/magicyuv.c
>> @@ -442,23 +442,26 @@ static int magy_decode_frame(AVCodecContext *avctx, void *data,
>> MagicYUVContext *s = avctx->priv_data;
>> ThreadFrame frame = { .f = data };
>> AVFrame *p = data;
>> - GetByteContext gbyte;
>> + GetByteContext gb;
>> uint32_t first_offset, offset, next_offset, header_size, slice_width;
>> int width, height, format, version, table_size;
>> int ret, i, j;
>>
>> - bytestream2_init(&gbyte, avpkt->data, avpkt->size);
>> - if (bytestream2_get_le32(&gbyte) != MKTAG('M', 'A', 'G', 'Y'))
>> + if (avpkt->size < 36)
>> + return AVERROR_INVALIDDATA;
>> +
>> + bytestream2_init(&gb, avpkt->data, avpkt->size);
>> + if (bytestream2_get_le32u(&gb) != MKTAG('M', 'A', 'G', 'Y'))
>> return AVERROR_INVALIDDATA;
>>
>> - header_size = bytestream2_get_le32(&gbyte);
>> + header_size = bytestream2_get_le32u(&gb);
>> if (header_size < 32 || header_size >= avpkt->size) {
>> av_log(avctx, AV_LOG_ERROR,
>> "header or packet too small %"PRIu32"\n", header_size);
>> return AVERROR_INVALIDDATA;
>> }
>>
>> - version = bytestream2_get_byte(&gbyte);
>> + version = bytestream2_get_byteu(&gb);
>> if (version != 7) {
>> avpriv_request_sample(avctx, "Version %d", version);
>> return AVERROR_PATCHWELCOME;
>> @@ -471,7 +474,7 @@ static int magy_decode_frame(AVCodecContext *avctx, void *data,
>> s->decorrelate = 0;
>> s->bps = 8;
>>
>> - format = bytestream2_get_byte(&gbyte);
>> + format = bytestream2_get_byteu(&gb);
>> switch (format) {
>> case 0x65:
>> avctx->pix_fmt = AV_PIX_FMT_GBRP;
>> @@ -552,34 +555,34 @@ static int magy_decode_frame(AVCodecContext *avctx, void *data,
>> s->magy_decode_slice = s->bps == 8 ? magy_decode_slice : magy_decode_slice10;
>> s->planes = av_pix_fmt_count_planes(avctx->pix_fmt);
>>
>> - bytestream2_skip(&gbyte, 1);
>> - s->color_matrix = bytestream2_get_byte(&gbyte);
>> - s->flags = bytestream2_get_byte(&gbyte);
>> + bytestream2_skipu(&gb, 1);
>> + s->color_matrix = bytestream2_get_byteu(&gb);
>> + s->flags = bytestream2_get_byteu(&gb);
>> s->interlaced = !!(s->flags & 2);
>> - bytestream2_skip(&gbyte, 3);
>> + bytestream2_skipu(&gb, 3);
>>
>> - width = bytestream2_get_le32(&gbyte);
>> - height = bytestream2_get_le32(&gbyte);
>> + width = bytestream2_get_le32u(&gb);
>> + height = bytestream2_get_le32u(&gb);
>> ret = ff_set_dimensions(avctx, width, height);
>> if (ret < 0)
>> return ret;
>>
>> - slice_width = bytestream2_get_le32(&gbyte);
>> + slice_width = bytestream2_get_le32u(&gb);
>> if (slice_width != avctx->coded_width) {
>> avpriv_request_sample(avctx, "Slice width %"PRIu32, slice_width);
>> return AVERROR_PATCHWELCOME;
>> }
>> - s->slice_height = bytestream2_get_le32(&gbyte);
>> + s->slice_height = bytestream2_get_le32u(&gb);
>> if (s->slice_height <= 0 || s->slice_height > INT_MAX - avctx->coded_height) {
>> av_log(avctx, AV_LOG_ERROR,
>> "invalid slice height: %d\n", s->slice_height);
>> return AVERROR_INVALIDDATA;
>> }
>>
>> - bytestream2_skip(&gbyte, 4);
>> + bytestream2_skipu(&gb, 4);
>>
>> s->nb_slices = (avctx->coded_height + s->slice_height - 1) / s->slice_height;
>> - if (s->nb_slices > INT_MAX / sizeof(Slice)) {
>> + if (s->nb_slices > INT_MAX / FFMAX(sizeof(Slice), 4 * 5)) {
>> av_log(avctx, AV_LOG_ERROR,
>> "invalid number of slices: %d\n", s->nb_slices);
>> return AVERROR_INVALIDDATA;
>> @@ -596,12 +599,14 @@ static int magy_decode_frame(AVCodecContext *avctx, void *data,
>> }
>> }
>>
>> + if (bytestream2_get_bytes_left(&gb) <= s->nb_slices * s->planes * 5)
>> + return AVERROR_INVALIDDATA;
>
> From where you picked this 5 number?
>
5 = 4 + 1. The four corresponds to the four byte read performed in the
loop below; the 1 corresponds to the skip below. <= instead of < because
of the byte containing the number of planes.
>> for (i = 0; i < s->planes; i++) {
>> av_fast_malloc(&s->slices[i], &s->slices_size[i], s->nb_slices * sizeof(Slice));
>> if (!s->slices[i])
>> return AVERROR(ENOMEM);
>>
>> - offset = bytestream2_get_le32(&gbyte);
>> + offset = bytestream2_get_le32u(&gb);
>> if (offset >= avpkt->size - header_size)
>> return AVERROR_INVALIDDATA;
>>
>> @@ -611,7 +616,7 @@ static int magy_decode_frame(AVCodecContext *avctx, void *data,
>> for (j = 0; j < s->nb_slices - 1; j++) {
>> s->slices[i][j].start = offset + header_size;
>>
>> - next_offset = bytestream2_get_le32(&gbyte);
>> + next_offset = bytestream2_get_le32u(&gb);
>> if (next_offset <= offset || next_offset >= avpkt->size - header_size)
>> return AVERROR_INVALIDDATA;
>>
>> @@ -625,16 +630,16 @@ static int magy_decode_frame(AVCodecContext *avctx, void *data,
>> s->slices[i][j].size = avpkt->size - s->slices[i][j].start;
>> }
>>
>> - if (bytestream2_get_byte(&gbyte) != s->planes)
>> + if (bytestream2_get_byteu(&gb) != s->planes)
>> return AVERROR_INVALIDDATA;
>>
>> - bytestream2_skip(&gbyte, s->nb_slices * s->planes);
>> + bytestream2_skipu(&gb, s->nb_slices * s->planes);
>>
>> - table_size = header_size + first_offset - bytestream2_tell(&gbyte);
>> + table_size = header_size + first_offset - bytestream2_tell(&gb);
>> if (table_size < 2)
>> return AVERROR_INVALIDDATA;
>>
>> - ret = build_huffman(avctx, avpkt->data + bytestream2_tell(&gbyte),
>> + ret = build_huffman(avctx, avpkt->data + bytestream2_tell(&gb),
>> table_size, s->max);
>> if (ret < 0)
>> return ret;
>> --
>> 2.25.1
>>
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