src/http/ngx_http_upstream.c:3764: error: Integer Overflow L2
  ([0, +oo] - 1):unsigned32 by call to `ngx_http_file_cache_free`.

src/http/ngx_http_upstream.c:3764:9: Call
3762.         }
3763. 
3764.         ngx_http_file_cache_free(r->cache, u->pipe->temp_file);
              ^
3765.     }
3766. 

src/http/ngx_http_file_cache.c:1449:1: <LHS trace>
1447. 
1448. 
1449. void
      ^
1450. ngx_http_file_cache_free(ngx_http_cache_t *c, ngx_temp_file_t *tf)
1451. {

src/http/ngx_http_file_cache.c:1449:1: Parameter `c->node->count`
  1447. 
  1448. 
  1449. void
        ^
  1450. ngx_http_file_cache_free(ngx_http_cache_t *c, ngx_temp_file_t *tf)
  1451. {

src/http/ngx_http_file_cache.c:1467:5: Binary operation: ([0, +oo] - 1):unsigned32 by call to `ngx_http_file_cache_free` 
  1465. 
  1466.     fcn = c->node;
  1467.     fcn->count--;
            ^
  1468. 
  1469.     if (c->updating && fcn->lock_time == c->lock_time) {
