src/core/ngx_slab.c:640: error: Integer Overflow L2
  ([0, `pool->pages->slab`] - 1):unsigned64 by call to `ngx_slab_free_pages`.

src/core/ngx_slab.c:460:1: Parameter `pool->pages->slab`
458. 
459. 
460. void
     ^
461. ngx_slab_free_locked(ngx_slab_pool_t *pool, void *p)
462. {

src/core/ngx_slab.c:477:5: Assignment
475.     n = ((u_char *) p - pool->start) >> ngx_pagesize_shift;
476.     page = &pool->pages[n];
477.     slab = page->slab;
         ^
478.     type = ngx_slab_page_type(page);
479. 

src/core/ngx_slab.c:638:9: Assignment
636.         }
637. 
638.         size = slab & ~NGX_SLAB_PAGE_START;
             ^
639. 
640.         ngx_slab_free_pages(pool, page, size);

src/core/ngx_slab.c:640:9: Call
638.         size = slab & ~NGX_SLAB_PAGE_START;
639. 
640.         ngx_slab_free_pages(pool, page, size);
             ^
641. 
642.         ngx_slab_junk(p, size << ngx_pagesize_shift);

src/core/ngx_slab.c:733:1: <LHS trace>
731. 
732. 
733. static void
     ^
734. ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
735.     ngx_uint_t pages)

src/core/ngx_slab.c:733:1: Parameter `pages`
  731. 
  732. 
  733. static void
       ^
  734. ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page,
  735.     ngx_uint_t pages)

src/core/ngx_slab.c:741:18: Binary operation: ([0, pool->pages->slab] - 1):unsigned64 by call to `ngx_slab_free_pages` 
  739.     pool->pfree += pages;
  740. 
  741.     page->slab = pages--;
                        ^
  742. 
  743.     if (pages) {
