From ed9fe15b4928f4f0358e978b9c315f590bc909e5 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sat, 24 Apr 2021 17:42:19 +0200 Subject: [PATCH] avformat/mpc8: Check for position overflow in mpc8_handle_chunk() Fixes: signed integer overflow: 15 + 9223372036854775796 cannot be represented in type 'long' Fixes: 29102/clusterfuzz-testcase-minimized-ffmpeg_dem_MPC8_fuzzer-6723520756318208 Fixes: 29102/clusterfuzz-testcase-minimized-ffmpeg_dem_MPC8_fuzzer-6739833034768384 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer (cherry picked from commit 8ef25d118246bf443900033fb3588dba628d11b0) Signed-off-by: Michael Niedermayer --- libavformat/mpc8.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/libavformat/mpc8.c b/libavformat/mpc8.c index 88c55e3d22..95813df748 100644 --- a/libavformat/mpc8.c +++ b/libavformat/mpc8.c @@ -205,8 +205,11 @@ static void mpc8_handle_chunk(AVFormatContext *s, int tag, int64_t chunk_pos, in switch(tag){ case TAG_SEEKTBLOFF: - pos = avio_tell(pb) + size; + pos = avio_tell(pb); off = ffio_read_varlen(pb); + if (pos > INT64_MAX - size || off < 0 || off > INT64_MAX - chunk_pos) + return; + pos += size; mpc8_parse_seektable(s, chunk_pos + off); avio_seek(pb, pos, SEEK_SET); break;