From b5e7092c9cc603ca9312dea1f0eb2bd331784fc1 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Wed, 17 Mar 2021 21:58:53 +0100 Subject: [PATCH] avformat/mpc8: check for size overflow in mpc8_get_chunk_header() Fixes: signed integer overflow: -9223372036854775760 - 50 cannot be represented in type 'long' Fixes: 31673/clusterfuzz-testcase-minimized-ffmpeg_dem_MPC8_fuzzer-580134751869337 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer (cherry picked from commit 6cc65d3d6760cfb08c5a9e57d4306d88428e18d0) Signed-off-by: Michael Niedermayer --- libavformat/mpc8.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/libavformat/mpc8.c b/libavformat/mpc8.c index f33323a599..88c55e3d22 100644 --- a/libavformat/mpc8.c +++ b/libavformat/mpc8.c @@ -127,7 +127,11 @@ static void mpc8_get_chunk_header(AVIOContext *pb, int *tag, int64_t *size) pos = avio_tell(pb); *tag = avio_rl16(pb); *size = ffio_read_varlen(pb); - *size -= avio_tell(pb) - pos; + pos -= avio_tell(pb); + if (av_sat_add64(*size, pos) != (uint64_t)*size + pos) { + *size = -1; + } else + *size += pos; } static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)