$ valgrind -q nomarch -t oob.arc > /dev/null ==9812== Invalid read of size 1 ==9812== at 0x1096A3: arc_extract_or_test (in /usr/bin/nomarch) ==9812== by 0x1089C4: main (in /usr/bin/nomarch) ==9812== Address 0x4a10210 is 0 bytes after a block of size 48 alloc'd ==9812== at 0x482E2BC: malloc (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) ==9812== by 0x108D9D: read_file_data (in /usr/bin/nomarch) ==9812== by 0x10959F: arc_extract_or_test (in /usr/bin/nomarch) ==9812== by 0x1089C4: main (in /usr/bin/nomarch) ==9812== ==9812== Conditional jump or move depends on uninitialised value(s) ==9812== at 0x1096D7: arc_extract_or_test (in /usr/bin/nomarch) ==9812== by 0x1089C4: main (in /usr/bin/nomarch) ==9812== nomarch: error reading record header Found using American Fuzzy Lop: http://lcamtuf.coredump.cx/afl/