On Mon, Oct 24, 2022 at 03:33:35PM -0400, Peter Xu wrote: > We used to have a report that pte-marker code can be reached even when > uffd-wp is not compiled in for file memories, here: > > https://lore.kernel.org/all/YzeR+R6b4bwBlBHh@x1n/T/#u > > I just got time to revisit this and found that the root cause is we simply > messed up with the vma check, so that for !PTE_MARKER_UFFD_WP system, we > will allow UFFDIO_REGISTER of MINOR & WP upon shmem as the check was wrong: > > if (vm_flags & VM_UFFD_MINOR) > return is_vm_hugetlb_page(vma) || vma_is_shmem(vma); > > Where we'll allow anything to pass on shmem as long as minor mode is > requested. > > Axel did it right when introducing minor mode but I messed it up in > b1f9e876862d when moving code around. Fix it. > > Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> > Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs") Should also have had: Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> -- Peter Xu
