panic: sandbox escaping file name "../file0", Files are map[../file0:true]

goroutine 16 [running]:
github.com/google/syzkaller/prog.(*randGen).filename(0xc000844860, 0xc00078c180, 0xbf4ce0, 0x0, 0x0)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/rand.go:161 +0x2e3
github.com/google/syzkaller/prog.(*BufferType).mutate(0xbf4ce0, 0xc000844860, 0xc00078c180, 0x8faa00, 0xc0006b7680, 0xc00078c148, 0xc0006b7650, 0x0, 0xc0006b7600, 0x53d24d8ff7c6cbfa, ...)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/mutation.go:264 +0x533
github.com/google/syzkaller/prog.(*Target).mutateArg(0xc0000711e0, 0xc000844860, 0xc00078c180, 0x8faa00, 0xc0006b7680, 0xc00078c148, 0xc0006b7650, 0x0, 0x4f0f00, 0xc0007b9e0f, ...)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/mutation.go:172 +0xe3
github.com/google/syzkaller/prog.(*mutator).mutateArg(0xc0007b9ed0, 0xa)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/mutation.go:153 +0x231
github.com/google/syzkaller/prog.(*Prog).Mutate(0xc00078c100, 0x8f8680, 0xc0005ce0f0, 0x1e, 0xc0005ebec0, 0xc0006a0000, 0xa14, 0xc00)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/mutation.go:34 +0x2db
main.(*Proc).loop(0xc0005ebf00)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:99 +0x446created by main.main
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:236 +0xfe2