Re: [PATCH v5 bpf-next 01/10] lib/buildid: harden build ID parsing logic

On Mon, Aug 12, 2024 at 5:52 PM Andi Kleen ak@linux.intel.com wrote:

...

@@ -152,6 +160,10 @@ int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, page = find_get_page(vma->vm_file->f_mapping, 0); if (!page) return -EFAULT; /* page not mapped */

• if (!PageUptodate(page)) {
  

•         put_page(page);
  

•         return -EFAULT;
  

• }
  

That change is not described. As I understand it might prevent reading previous data in the page or maybe junk under an IO error? Anyways I guess it's a good change.

From what I understood, one can get a valid page from the find_get_page() (same for folio), but it might not be yet completely filled out. PageUptodate() is supposed to detect this and prevent the use of incomplete page data.

Reviewed-by: Andi Kleen ak@linux.intel.com

-Andi