vma_can_userfault() masks off non-userfaultfd VM flags from vm_flags. The vm_flags & VM_DROPPABLE test will then always be false, incorrectly allowing VM_DROPPABLE regions to be registered with userfaultfd. Additionally, vm_flags is not guaranteed to correspond to the actual VMA's flags. Fix this test by checking the VMA's flags directly. Link: https://lore.kernel.org/linux-mm/5a875a3a-2243-4eab-856f-bc53ccfec3ea@xxxxxxxxxx/ Fixes: 9651fcedf7b9 ("mm: add MAP_DROPPABLE for designating always lazily freeable mappings") Signed-off-by: Tal Zussman <tz2294@xxxxxxxxxxxx> --- include/linux/userfaultfd_k.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 75342022d144..f3b3d2c9dd5e 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -218,7 +218,7 @@ static inline bool vma_can_userfault(struct vm_area_struct *vma, { vm_flags &= __VM_UFFD_FLAGS; - if (vm_flags & VM_DROPPABLE) + if (vma->vm_flags & VM_DROPPABLE) return false; if ((vm_flags & VM_UFFD_MINOR) && -- 2.39.5
