Privilege Escalation Linux

I need help with privilege escalation on linux ;
I have a root (suid bit) executable which requires a password to enter, I don’t know the password and I can’t disassemble as chmod 4711 permissions block reading.
tried LD_PRELOAD but it doesn’t work ;
I saw inside with strace
the source should be structured something like this:

int main(int argc, char* argv[]){
 setresuid(geteuid(), geteuid(), geteuid());
   if (strcmp(argv[1], "realpassword") == 0) system(/bin/sh);  
     else { printf("Invalid password\n"); }

Do you have any ideas to recommend me?

C’s strcmp prematurely returns when the two characters being compared are not equal. You might be able to perform a timing attack to uncover the password present in the if-condition in a character-by-character fashion.