Null pointer dereference in libr/bin/format/mach0/mach0.c in radareorg/radare2 in radareorg/radare2

Null pointer dereference in libr/bin/format/mach0/mach0.c in radareorg/radare2 in GitHub repository radareorg/radare2 prior to 5.7.0. It is likely to be exploitable. For more general description of heap buffer overflow, see [CWE](https://cwe.mitre.org/data/definitions/476.html).