avformat/hls: Limit start_seq_no to one bit less

This avoids overflow checks on additions with 32bit numbers

Fixes: signed integer overflow: 9223372036854775806 + 2 cannot be represented in type 'long'
Fixes: 44012/clusterfuzz-testcase-minimized-ffmpeg_dem_HLS_fuzzer-4747770734444544
Fixes: 48065/clusterfuzz-testcase-minimized-ffmpeg_dem_HLS_fuzzer-5372410355908608

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit d8ee01425459aaafe36acc7743b3f9f28a01821b)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2022-06-16 23:02:11 +02:00
parent 58e57ef180
commit 35ccd5a569
No known key found for this signature in database
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@ -826,10 +826,10 @@ static int parse_playlist(HLSContext *c, const char *url,
if (ret < 0)
goto fail;
seq_no = strtoull(ptr, NULL, 10);
if (seq_no > INT64_MAX) {
if (seq_no > INT64_MAX/2) {
av_log(c->ctx, AV_LOG_DEBUG, "MEDIA-SEQUENCE higher than "
"INT64_MAX, mask out the highest bit\n");
seq_no &= INT64_MAX;
"INT64_MAX/2, mask out the highest bit\n");
seq_no &= INT64_MAX/2;
}
pls->start_seq_no = seq_no;
} else if (av_strstart(line, "#EXT-X-PLAYLIST-TYPE:", &ptr)) {