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avcodec/ccaption_dec: do not modify packet data in case of parity error 

To dissallow similar errors in future, make pointers const.
This commit is contained in:
Paul B Mahol 2020-06-19 16:23:53 +02:00
parent bbd0be04d0
commit bd1b78e91a
1 changed files with 8 additions and 8 deletions
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16
libavcodec/ccaption_dec.c
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@ -341,11 +341,13 @@ static void write_char(CCaptionSubContext *ctx, struct Screen *screen, char ch)
* If the second byte doesn't pass parity, it returns INVALIDDATA
* user can ignore the whole pair and pass the other pair.
*/
static int validate_cc_data_pair(uint8_t *cc_data_pair)
static int validate_cc_data_pair(const uint8_t *cc_data_pair, uint8_t *hi)
{
uint8_t cc_valid = (*cc_data_pair & 4) >>2;
uint8_t cc_type = *cc_data_pair & 3;
*hi = cc_data_pair[1];
if (!cc_valid)
return AVERROR_INVALIDDATA;
@ -355,7 +357,7 @@ static int validate_cc_data_pair(uint8_t *cc_data_pair)
return AVERROR_INVALIDDATA;
}
if (!av_parity(cc_data_pair[1])) {
cc_data_pair[1]=0x7F;
*hi = 0x7F;
}
}
@ -782,26 +784,24 @@ static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avp
int64_t start_time;
int64_t end_time;
int bidx = ctx->buffer_index;
uint8_t *bptr = NULL;
const uint8_t *bptr = avpkt->data;
int len = avpkt->size;
int ret = 0;
int i;
bptr = avpkt->data;
for (i = 0; i < len; i += 3) {
uint8_t cc_type = bptr[i] & 1;
uint8_t hi, cc_type = bptr[i] & 1;
if (ctx->data_field < 0)
ctx->data_field = cc_type;
if (validate_cc_data_pair(bptr + i))
if (validate_cc_data_pair(bptr + i, &hi))
continue;
if (cc_type != ctx->data_field)
continue;
ret = process_cc608(ctx, bptr[i + 1] & 0x7f, bptr[i + 2] & 0x7f);
ret = process_cc608(ctx, hi & 0x7f, bptr[i + 2] & 0x7f);
if (ret < 0)
return ret;