[PATCH v4 2/2] mm/userfaultfd: add VM_WARN_ONCE()

[Muhammad Usama Anjum <usama.anjum@collabora.com>]

Add VM_WARN_ONCE() to uffd_wp_range() to detect range (start, len) abuse.

Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
---
 mm/userfaultfd.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 77c5839e591c..d89ed44d2668 100644
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -717,6 +717,8 @@ long uffd_wp_range(struct mm_struct *dst_mm, struct vm_area_struct *dst_vma,
 	struct mmu_gather tlb;
 	long ret;
 
+	VM_WARN_ONCE(start < dst_vma->vm_start || start + len > dst_vma->vm_end,
+		     "The address range exceeds VMA boundary.\n");
 	if (enable_wp)
 		mm_cp_flags = MM_CP_UFFD_WP;
 	else
-- 
2.39.1