mruby:mruby_fuzzer: Command injection in mrb_sysread_dummy

Detailed Report: https://oss-fuzz.com/testcase?key=4519883110481920 Project: mruby Fuzzing Engine: libFuzzer Fuzz Target: mrubyfuzzer Job Type: libfuzzermsanmruby Platform Id: linux Crash Type: Command injection Crash Address: Crash State: mrbsysreaddummy mrbiosysreadcommon mrbiosysread Sanitizer...