From 7e665e4a81e2e96eb45138a1dfa38617de2631a4 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Fri, 15 Nov 2019 23:00:51 +0100 Subject: [PATCH] avformat/rmdec: Initialize and sanity check offset in ivr_read_header() Fixes: signed integer overflow: -9223372036854775808 - 17 cannot be represented in type 'long' Fixes: 18768/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5674385247830016 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavformat/rmdec.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c index 2c40b866aa..088bd75b69 100644 --- a/libavformat/rmdec.c +++ b/libavformat/rmdec.c @@ -1171,7 +1171,7 @@ static int ivr_read_header(AVFormatContext *s) uint8_t key[256], val[256]; AVIOContext *pb = s->pb; AVStream *st; - int64_t pos, offset, temp; + int64_t pos, offset=0, temp; pos = avio_tell(pb); tag = avio_rl32(pb); @@ -1188,6 +1188,8 @@ static int ivr_read_header(AVFormatContext *s) offset = temp; temp = avio_rb64(pb); } + if (offset <= 0) + return AVERROR_INVALIDDATA; avio_skip(pb, offset - avio_tell(pb)); if (avio_r8(pb) != 1) return AVERROR_INVALIDDATA;