alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
		unsigned long addr, int node, bool hugepage)
{
	struct mempolicy *pol;
	struct page *page;
	int preferred_nid;
	nodemask_t *nmask;

	pol = get_vma_policy(vma, addr);

	if (pol->mode == MPOL_INTERLEAVE) {
		unsigned nid;

		nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
		mpol_cond_put(pol);
		page = alloc_page_interleave(gfp, order, nid);
		goto out;
	}

	if (unlikely(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hugepage)) {
		int hpage_node = node;

		/*
		 * For hugepage allocation and non-interleave policy which
		 * allows the current node (or other explicitly preferred
		 * node) we only try to allocate from the current/preferred
		 * node and don't fall back to other nodes, as the cost of
		 * remote accesses would likely offset THP benefits.
		 *
		 * If the policy is interleave, or does not allow the current
		 * node in its nodemask, we allocate the standard way.
		 */
		if (pol->mode == MPOL_PREFERRED &&
						!(pol->flags & MPOL_F_LOCAL))
			hpage_node = pol->v.preferred_node;

		nmask = policy_nodemask(gfp, pol);
		if (!nmask || node_isset(hpage_node, *nmask)) {
			mpol_cond_put(pol);
			page = __alloc_pages_node(hpage_node,
						gfp | __GFP_THISNODE, order);
			goto out;
		}
	}

	nmask = policy_nodemask(gfp, pol);
	preferred_nid = policy_node(gfp, pol, node);
	page = __alloc_pages_nodemask(gfp, order, preferred_nid, nmask);
	mpol_cond_put(pol);
out:
	return page;
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.