Such as: // x.c #include <stdio.h> int main(void) { char x[] = "abc"; printf("%s\n", x); return 0; } and using GCC compile it: ➜ gcc x.c -v ...... /usr/libexec/gcc/x86_64-redhat-linux/5.1.1/cc1 -quiet -v x.c -quiet -dumpbase x.c -mtune=generic -march=x86-64 -auxbase x -version -o /tmp/ccqowh4f.s ...... as you see, GCC not enabled the -fstack-protector by default. And in Ubuntu: ➜ gcc x.c -v /usr/lib/gcc/x86_64-linux-gnu/4.6/cc1 -quiet -v -imultilib . -imultiarch x86_64-linux-gnu x.c -quiet -dumpbase x.c -mtune=generic -march=x86-64 -auxbase x -version -fstack-protector -o /tmp/cc0aswkw.s the enabled the -fstack-protector by default. why?