Are string literals _always_ allocated in the RO section?

This program:

void x(char *s)
{
    *s= 'x';
}

main()
{
    x("y");
}

is compiled plainly but cathes SIGSEGV in the 

        *s= 'x' 

line.  And it's because the string "y" is put in the .text section.
And the fact that the x()'s parm is explicitly declared as <char*>,
not <const char*> does nothing in this case.  Should it be considered
as a bug?