src/core/ngx_string.c:618: error: Integer Overflow L2
  ([0, `len`] - 1):unsigned64.

src/core/ngx_string.c:606:1: <LHS trace>
604. 
605. 
606. u_char *
     ^
607. ngx_strnstr(u_char *s1, char *s2, size_t len)
608. {

src/core/ngx_string.c:606:1: Parameter `len`
604. 
605. 
606. u_char *
     ^
607. ngx_strnstr(u_char *s1, char *s2, size_t len)
608. {

src/core/ngx_string.c:618:17: Binary operation: ([0, len] - 1):unsigned64
616.     do {
617.         do {
618.             if (len-- == 0) {
                     ^
619.                 return NULL;
620.             }
