Hi! I was fuzzing expr in coreutils and found a bug. I compiled expr with asan and ubsan. I cloned the repository from https://github.com/coreutils/coreutils and I am using commit f7e25d5bb53e35bcdea8512dd6db07dd7e6cf452 . After compiling expr, just run './expr $(printf "\x30\x98\xc8\x9d") : $(printf "\x5c\x28\x5c\x29\x2e\x2a\x5c\x53\x98\xc8\x30\x2a\x5c\x31")' and observe the crash. I have attached the ASAN report which I got from my run to this email.