avformat/rmdec: Check codec_length without overflow

Fixes: signed integer overflow: 2147483647 + 64 cannot be represented in type 'int'
Fixes: 30333/clusterfuzz-testcase-minimized-ffmpeg_dem_RM_fuzzer-5175286983426048
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
index 521b9d0e8c6f075ea4d4c446f0d2f20191c2a22f..610189ecb40346502985f5a35c68f197bdd7424a 100644 (file)
--- a/libavformat/rmdec.c
+++ b/libavformat/rmdec.c
@@ -223,7 +223,7 @@ static int rm_read_audio_stream_info(AVFormatContext *s, AVIOContext *pb,
                 if (version == 5)
                     avio_r8(pb);
                 codecdata_length = avio_rb32(pb);
-                if(codecdata_length + AV_INPUT_BUFFER_PADDING_SIZE <= (unsigned)codecdata_length){
+                if((unsigned)codecdata_length > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE){
                     av_log(s, AV_LOG_ERROR, "codecdata_length too large\n");
                     return -1;
                 }