From 2bbef69b0ba938cce4f9d61bed46d3f3058e56c2 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sun, 1 Aug 2021 20:25:20 +0200 Subject: [PATCH] avformat/mpc8: Check first keyframe position for overflow Fixes: signed integer overflow: 9223372036854775791 + 18 cannot be represented in type 'long' Fixes: 36307/clusterfuzz-testcase-minimized-ffmpeg_dem_MPC8_fuzzer-4917863877050368 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavformat/mpc8.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/libavformat/mpc8.c b/libavformat/mpc8.c index df5d345f85..a0e661c2ab 100644 --- a/libavformat/mpc8.c +++ b/libavformat/mpc8.c @@ -177,7 +177,13 @@ static void mpc8_parse_seektable(AVFormatContext *s, int64_t off) } seekd = get_bits(&gb, 4); for(i = 0; i < 2; i++){ - pos = gb_get_v(&gb) + c->header_pos; + pos = gb_get_v(&gb); + if (av_sat_add64(pos, c->header_pos) != pos + (uint64_t)c->header_pos) { + av_free(buf); + return; + } + + pos += c->header_pos; ppos[1 - i] = pos; av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME); }