patch by Vladimir Bashkirtsev diff -uNr ceph-15.2.4/src/erasure-code/shec/ErasureCodeShec.cc ceph-15.2.4-fix_ErasureCodeShec/src/erasure-code/shec/ErasureCodeShec.cc --- ceph-15.2.4/src/erasure-code/shec/ErasureCodeShec.cc 2020-07-01 01:10:51.000000000 +0930 +++ ceph-15.2.4-fix_ErasureCodeShec/src/erasure-code/shec/ErasureCodeShec.cc 2020-11-14 00:46:20.029488684 +1030 @@ -197,7 +197,10 @@ } unsigned int k = get_data_chunk_count(); unsigned int m = get_chunk_count() - k; - unsigned blocksize = (*chunks.begin()).second.length(); + unsigned blocksize = 0; + if (chunks.size() > 0) { + blocksize = (*chunks.begin()).second.length(); + } for (unsigned int i = 0; i < k + m; i++) { if (chunks.find(i) == chunks.end()) { bufferlist tmp;