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avformat/framecrcenc: Don't read after the end of side-data

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Nothing guarantees that the size of side data containing a palette
is actually divisible by four (although it should be); but for
big-endian systems, an algorithm is used that presupposed this.
So switch to an algorithm that does not overread: It processes
four bytes at a time, but only if all of them are contained in
the side data.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-12-06 01:45:14 +01:00
parent fa4532a1f7
commit b8fe417c19
1 changed files with 7 additions and 5 deletions
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12
libavformat/framecrcenc.c
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@ -23,6 +23,7 @@
#include "libavutil/adler32.h"
#include "libavutil/avstring.h"
#include "libavutil/intreadwrite.h"
#include "avformat.h"
#include "internal.h"
@ -52,16 +53,17 @@ static int framecrc_write_packet(struct AVFormatContext *s, AVPacket *pkt)
if (pkt->flags != AV_PKT_FLAG_KEY)
av_strlcatf(buf, sizeof(buf), ", F=0x%0X", pkt->flags);
if (pkt->side_data_elems) {
int i, j;
int i;
av_strlcatf(buf, sizeof(buf), ", S=%d", pkt->side_data_elems);
for (i=0; i<pkt->side_data_elems; i++) {
const AVPacketSideData *const sd = &pkt->side_data[i];
uint32_t side_data_crc = 0;
if (HAVE_BIGENDIAN && AV_PKT_DATA_PALETTE == pkt->side_data[i].type) {
for (j=0; j<pkt->side_data[i].size; j++) {
side_data_crc = av_adler32_update(side_data_crc,
pkt->side_data[i].data + (j^3),
1);
for (int j = 0; j < sd->size / 4; j++) {
uint8_t buf[4];
AV_WL32(buf, AV_RB32(sd->data + 4 * j));
side_data_crc = av_adler32_update(side_data_crc, buf, 4);
}
} else {
side_data_crc = av_adler32_update(0,