libfuzzer's -jobs option will, depending on the number of CPUs, spin up a WorkerThread and end up printing the log file using CopyFileToErr. This leads to an MSan false positive. This patch disables the MSan interceptor checks, similarly to other instances in https://reviews.llvm.org/D48891 Side-note: this false positive issue first appeared when printf() was replaced by puts() (90b4d1bcb20180c591385131b12fa90d2e4860b1). The interceptor check was always present; however, MSan does not check_printf by default.
See http://llvm.org/docs/LibFuzzer.html