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avcodec/magicyuv: Avoid intermediate array when parsing Huffman tables

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Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-08-31 21:14:54 +02:00
parent 61499c6456
commit a13a23bdf2
1 changed files with 8 additions and 13 deletions
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21
libavcodec/magicyuv.c
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@ -68,7 +68,6 @@ typedef struct MagicYUVContext {
int vshift[4];
Slice *slices[4]; // slice bitstream positions for each plane
unsigned int slices_size[4]; // slice sizes for each plane
uint8_t len[4096]; // scratch table of code lengths
VLC vlc[4]; // VLC for each plane
int (*magy_decode_slice)(AVCodecContext *avctx, void *tdata,
int j, int threadnr);
@ -81,18 +80,11 @@ static int huff_cmp_len(const void *a, const void *b)
return (aa->len - bb->len) * 4096 + bb->sym - aa->sym;
}
static int huff_build(VLC *vlc, uint8_t *len, int nb_elems)
static int huff_build(HuffEntry he[], VLC *vlc, int nb_elems)
{
HuffEntry he[4096];
uint32_t code;
int i;
for (i = 0; i < nb_elems; i++) {
he[i].sym = i;
he[i].len = len[i];
if (len[i] == 0 || len[i] > 32)
return AVERROR_INVALIDDATA;
}
AV_QSORT(he, nb_elems, HuffEntry, huff_cmp_len);
code = 1;
@ -396,6 +388,7 @@ static int magy_decode_slice(AVCodecContext *avctx, void *tdata,
static int build_huffman(AVCodecContext *avctx, GetBitContext *gbit, int max)
{
MagicYUVContext *s = avctx->priv_data;
HuffEntry he[4096];
int i = 0, j = 0, k;
while (get_bits_left(gbit) >= 8) {
@ -404,17 +397,19 @@ static int build_huffman(AVCodecContext *avctx, GetBitContext *gbit, int max)
int l = get_bitsz(gbit, b * 8) + 1;
k = j + l;
if (k > max) {
if (k > max || x == 0 || x > 32) {
av_log(avctx, AV_LOG_ERROR, "Invalid Huffman codes\n");
return AVERROR_INVALIDDATA;
}
for (; j < k; j++)
s->len[j] = x;
for (; j < k; j++) {
he[j].sym = j;
he[j].len = x;
}
if (j == max) {
j = 0;
if (huff_build(&s->vlc[i], s->len, max)) {
if (huff_build(he, &s->vlc[i], max)) {
av_log(avctx, AV_LOG_ERROR, "Cannot build Huffman codes\n");
return AVERROR_INVALIDDATA;
}